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class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Principles" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Principles"> <div class="vector-toc-text"> 3 Principles </div> </a> <button aria-controls="toc-Principles-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Principles subsection </button> <ul id="toc-Principles-sublist" class="vector-toc-list"> <li id="toc-More_detailed_description" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#More_detailed_description"> <div class="vector-toc-text"> 3.1 More detailed description </div> </a> <ul id="toc-More_detailed_description-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-User-satellite_geometry" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#User-satellite_geometry"> <div class="vector-toc-text"> 3.2 User-satellite geometry </div> </a> <ul id="toc-User-satellite_geometry-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Receiver_in_continuous_operation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Receiver_in_continuous_operation"> <div class="vector-toc-text"> 3.3 Receiver in continuous operation </div> </a> <ul id="toc-Receiver_in_continuous_operation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Non-navigation_applications" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Non-navigation_applications"> <div class="vector-toc-text"> 3.4 Non-navigation applications </div> </a> <ul id="toc-Non-navigation_applications-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Structure" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Structure"> <div class="vector-toc-text"> 4 Structure </div> </a> <button aria-controls="toc-Structure-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Structure subsection </button> <ul id="toc-Structure-sublist" class="vector-toc-list"> <li id="toc-Space_segment" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Space_segment"> <div class="vector-toc-text"> 4.1 Space segment </div> </a> <ul id="toc-Space_segment-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Control_segment" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Control_segment"> <div class="vector-toc-text"> 4.2 Control segment </div> </a> <ul id="toc-Control_segment-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-User_segment" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#User_segment"> <div class="vector-toc-text"> 4.3 User segment </div> </a> <ul id="toc-User_segment-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Applications" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Applications"> <div class="vector-toc-text"> 5 Applications </div> </a> <button aria-controls="toc-Applications-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Applications subsection </button> <ul id="toc-Applications-sublist" class="vector-toc-list"> <li id="toc-Civilian" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Civilian"> <div class="vector-toc-text"> 5.1 Civilian </div> </a> <ul id="toc-Civilian-sublist" class="vector-toc-list"> <li id="toc-Restrictions_on_civilian_use" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Restrictions_on_civilian_use"> <div class="vector-toc-text"> 5.1.1 Restrictions on civilian use </div> </a> <ul id="toc-Restrictions_on_civilian_use-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Military" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Military"> <div class="vector-toc-text"> 5.2 Military </div> </a> <ul id="toc-Military-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Timekeeping" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Timekeeping"> <div class="vector-toc-text"> 5.3 Timekeeping </div> </a> <ul id="toc-Timekeeping-sublist" class="vector-toc-list"> <li id="toc-Leap_seconds" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Leap_seconds"> <div class="vector-toc-text"> 5.3.1 Leap seconds </div> </a> <ul id="toc-Leap_seconds-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Accuracy" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Accuracy"> <div class="vector-toc-text"> 5.3.2 Accuracy </div> </a> <ul id="toc-Accuracy-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Relativistic_corrections" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Relativistic_corrections"> <div class="vector-toc-text"> 5.3.3 Relativistic corrections </div> </a> <ul id="toc-Relativistic_corrections-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Format" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Format"> <div class="vector-toc-text"> 5.3.4 Format </div> </a> <ul id="toc-Format-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Communication" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Communication"> <div class="vector-toc-text"> 6 Communication </div> </a> <button aria-controls="toc-Communication-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Communication subsection </button> <ul id="toc-Communication-sublist" class="vector-toc-list"> <li id="toc-Message_format" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Message_format"> <div class="vector-toc-text"> 6.1 Message format </div> </a> <ul id="toc-Message_format-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Satellite_frequencies" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Satellite_frequencies"> <div class="vector-toc-text"> 6.2 Satellite frequencies </div> </a> <ul id="toc-Satellite_frequencies-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Demodulation_and_decoding" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Demodulation_and_decoding"> <div class="vector-toc-text"> 6.3 Demodulation and decoding </div> </a> <ul id="toc-Demodulation_and_decoding-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Navigation_equations" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Navigation_equations"> <div class="vector-toc-text"> 7 Navigation equations </div> </a> <button aria-controls="toc-Navigation_equations-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Navigation equations subsection </button> <ul id="toc-Navigation_equations-sublist" class="vector-toc-list"> <li id="toc-Problem_statement" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Problem_statement"> <div class="vector-toc-text"> 7.1 Problem statement </div> </a> <ul id="toc-Problem_statement-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Geometric_interpretation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Geometric_interpretation"> <div class="vector-toc-text"> 7.2 Geometric interpretation </div> </a> <ul id="toc-Geometric_interpretation-sublist" class="vector-toc-list"> <li id="toc-Spheres" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Spheres"> <div class="vector-toc-text"> 7.2.1 Spheres </div> </a> <ul id="toc-Spheres-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hyperboloids" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Hyperboloids"> <div class="vector-toc-text"> 7.2.2 Hyperboloids </div> </a> <ul id="toc-Hyperboloids-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Inscribed_sphere" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Inscribed_sphere"> <div class="vector-toc-text"> 7.2.3 Inscribed sphere </div> </a> <ul id="toc-Inscribed_sphere-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hypercones" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Hypercones"> <div class="vector-toc-text"> 7.2.4 Hypercones </div> </a> <ul id="toc-Hypercones-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Solution_methods" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Solution_methods"> <div class="vector-toc-text"> 7.3 Solution methods </div> </a> <ul id="toc-Solution_methods-sublist" class="vector-toc-list"> <li id="toc-Least_squares" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Least_squares"> <div class="vector-toc-text"> 7.3.1 Least squares </div> </a> <ul id="toc-Least_squares-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Iterative" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Iterative"> <div class="vector-toc-text"> 7.3.2 Iterative </div> </a> <ul id="toc-Iterative-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Closed-form" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Closed-form"> <div class="vector-toc-text"> 7.3.3 Closed-form </div> </a> <ul id="toc-Closed-form-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Error_sources_and_analysis" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Error_sources_and_analysis"> <div class="vector-toc-text"> 7.4 Error sources and analysis </div> </a> <ul id="toc-Error_sources_and_analysis-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Accuracy_enhancement_and_surveying" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Accuracy_enhancement_and_surveying"> <div class="vector-toc-text"> 8 Accuracy enhancement and surveying </div> </a> <ul id="toc-Accuracy_enhancement_and_surveying-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Regulatory_spectrum_issues_concerning_GPS_receivers" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Regulatory_spectrum_issues_concerning_GPS_receivers"> <div class="vector-toc-text"> 9 Regulatory spectrum issues concerning GPS receivers </div> </a> <ul id="toc-Regulatory_spectrum_issues_concerning_GPS_receivers-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Similar_systems" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Similar_systems"> <div class="vector-toc-text"> 10 Similar systems </div> </a> <ul id="toc-Similar_systems-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Backup_system" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Backup_system"> <div class="vector-toc-text"> 11 Backup system </div> </a> <ul id="toc-Backup_system-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> 12 See also </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> 13 Notes </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> 14 References </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> 15 Further reading </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> 16 External links </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" > Toggle the table of contents </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading">Global Positioning System</h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 116 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-116" aria-hidden="true" > 116 languages </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/GPS" title="GPS – Afrikaans" lang="af" hreflang="af" data-title="GPS" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target">Afrikaans</a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%86%D8%B8%D8%A7%D9%85_%D8%A7%D9%84%D8%AA%D9%85%D9%88%D8%B6%D8%B9_%D8%A7%D9%84%D8%B9%D8%A7%D9%84%D9%85%D9%8A" title="نظام التموضع العالمي – Arabic" lang="ar" hreflang="ar" data-title="نظام التموضع العالمي" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target">العربية</a></li><li class="interlanguage-link interwiki-an mw-list-item"><a href="https://an.wikipedia.org/wiki/Sistema_de_Posicionamiento_Global" title="Sistema de Posicionamiento Global – Aragonese" lang="an" hreflang="an" data-title="Sistema de Posicionamiento Global" data-language-autonym="Aragonés" data-language-local-name="Aragonese" class="interlanguage-link-target">Aragonés</a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/GPS" title="GPS – Asturian" lang="ast" hreflang="ast" data-title="GPS" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target">Asturianu</a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/GPS" title="GPS – Azerbaijani" lang="az" hreflang="az" data-title="GPS" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target">Azərbaycanca</a></li><li class="interlanguage-link interwiki-azb mw-list-item"><a href="https://azb.wikipedia.org/wiki/%D9%82%D9%84%D9%88%D8%A8%D8%A7%D9%84_%D9%85%D8%A4%D9%82%D8%B9%DB%8C%D8%AA_%D8%AA%D8%B9%DB%8C%DB%8C%D9%86_%D8%A7%D8%A6%D8%AA%D9%85%D9%87_%D8%B3%DB%8C%D8%B3%D8%AA%D9%85%DB%8C" title="قلوبال مؤقعیت تعیین ائتمه سیستمی – South Azerbaijani" lang="azb" hreflang="azb" data-title="قلوبال مؤقعیت تعیین ائتمه سیستمی" data-language-autonym="تۆرکجه" data-language-local-name="South Azerbaijani" class="interlanguage-link-target">تۆرکجه</a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%AC%E0%A6%BF%E0%A6%B6%E0%A7%8D%E0%A6%AC%E0%A6%9C%E0%A6%A8%E0%A7%80%E0%A6%A8_%E0%A6%85%E0%A6%AC%E0%A6%B8%E0%A7%8D%E0%A6%A5%E0%A6%BE%E0%A6%A8-%E0%A6%A8%E0%A6%BF%E0%A6%B0%E0%A7%8D%E0%A6%A3%E0%A6%BE%E0%A6%AF%E0%A6%BC%E0%A6%95_%E0%A6%AC%E0%A7%8D%E0%A6%AF%E0%A6%AC%E0%A6%B8%E0%A7%8D%E0%A6%A5%E0%A6%BE" title="বিশ্বজনীন অবস্থান-নির্ণায়ক ব্যবস্থা – Bangla" lang="bn" hreflang="bn" data-title="বিশ্বজনীন অবস্থান-নির্ণায়ক ব্যবস্থা" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target">বাংলা</a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/Cho%C3%A2n-ki%C3%BB_T%C4%93ng-%C5%ABi_H%C4%93-th%C3%B3ng" title="Choân-kiû Tēng-ūi Hē-thóng – Minnan" lang="nan" hreflang="nan" data-title="Choân-kiû Tēng-ūi Hē-thóng" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="Minnan" class="interlanguage-link-target">閩南語 / Bân-lâm-gú</a></li><li class="interlanguage-link interwiki-ba mw-list-item"><a href="https://ba.wikipedia.org/wiki/GPS" title="GPS – Bashkir" lang="ba" hreflang="ba" data-title="GPS" data-language-autonym="Башҡортса" data-language-local-name="Bashkir" class="interlanguage-link-target">Башҡортса</a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/GPS" title="GPS – Belarusian" lang="be" hreflang="be" data-title="GPS" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target">Беларуская</a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%93%D0%BB%D0%BE%D0%B1%D0%B0%D0%BB%D0%BD%D0%B0_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0_%D0%B7%D0%B0_%D0%BF%D0%BE%D0%B7%D0%B8%D1%86%D0%B8%D0%BE%D0%BD%D0%B8%D1%80%D0%B0%D0%BD%D0%B5" title="Глобална система за позициониране – Bulgarian" lang="bg" hreflang="bg" data-title="Глобална система за позициониране" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target">Български</a></li><li class="interlanguage-link interwiki-bar mw-list-item"><a href="https://bar.wikipedia.org/wiki/GPS" title="GPS – Bavarian" lang="bar" hreflang="bar" data-title="GPS" data-language-autonym="Boarisch" data-language-local-name="Bavarian" class="interlanguage-link-target">Boarisch</a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Globalni_pozicioni_sistem" title="Globalni pozicioni sistem – Bosnian" lang="bs" hreflang="bs" data-title="Globalni pozicioni sistem" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target">Bosanski</a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Breton" lang="br" hreflang="br" data-title="Global Positioning System" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target">Brezhoneg</a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Sistema_de_posicionament_global" title="Sistema de posicionament global – Catalan" lang="ca" hreflang="ca" data-title="Sistema de posicionament global" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target">Català</a></li><li class="interlanguage-link interwiki-cs badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://cs.wikipedia.org/wiki/GPS" title="GPS – Czech" lang="cs" hreflang="cs" data-title="GPS" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target">Čeština</a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/GPS" title="GPS – Danish" lang="da" hreflang="da" data-title="GPS" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target">Dansk</a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – German" lang="de" hreflang="de" data-title="Global Positioning System" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target">Deutsch</a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/GPS" title="GPS – Estonian" lang="et" hreflang="et" data-title="GPS" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target">Eesti</a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Greek" lang="el" hreflang="el" data-title="Global Positioning System" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target">Ελληνικά</a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/GPS" title="GPS – Spanish" lang="es" hreflang="es" data-title="GPS" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target">Español</a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Tutmonda_loktrova_sistemo" title="Tutmonda loktrova sistemo – Esperanto" lang="eo" hreflang="eo" data-title="Tutmonda loktrova sistemo" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target">Esperanto</a></li><li class="interlanguage-link interwiki-ext mw-list-item"><a href="https://ext.wikipedia.org/wiki/GPS" title="GPS – Extremaduran" lang="ext" hreflang="ext" data-title="GPS" data-language-autonym="Estremeñu" data-language-local-name="Extremaduran" class="interlanguage-link-target">Estremeñu</a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/GPS" title="GPS – Basque" lang="eu" hreflang="eu" data-title="GPS" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target">Euskara</a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B3%D8%A7%D9%85%D8%A7%D9%86%D9%87_%D9%85%D9%88%D9%82%D8%B9%DB%8C%D8%AA%E2%80%8C%DB%8C%D8%A7%D8%A8_%D8%AC%D9%87%D8%A7%D9%86%DB%8C" title="سامانه موقعیت‌یاب جهانی – Persian" lang="fa" hreflang="fa" data-title="سامانه موقعیت‌یاب جهانی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target">فارسی</a></li><li class="interlanguage-link interwiki-fo mw-list-item"><a href="https://fo.wikipedia.org/wiki/GPS" title="GPS – Faroese" lang="fo" hreflang="fo" data-title="GPS" data-language-autonym="Føroyskt" data-language-local-name="Faroese" class="interlanguage-link-target">Føroyskt</a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – French" lang="fr" hreflang="fr" data-title="Global Positioning System" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target">Français</a></li><li class="interlanguage-link interwiki-fy mw-list-item"><a href="https://fy.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Western Frisian" lang="fy" hreflang="fy" data-title="Global Positioning System" data-language-autonym="Frysk" data-language-local-name="Western Frisian" class="interlanguage-link-target">Frysk</a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/C%C3%B3ras_Suite_Domhanda" title="Córas Suite Domhanda – Irish" lang="ga" hreflang="ga" data-title="Córas Suite Domhanda" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target">Gaeilge</a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Sistema_de_posicionamento_global" title="Sistema de posicionamento global – Galician" lang="gl" hreflang="gl" data-title="Sistema de posicionamento global" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target">Galego</a></li><li class="interlanguage-link interwiki-gan mw-list-item"><a href="https://gan.wikipedia.org/wiki/GPS" title="GPS – Gan" lang="gan" hreflang="gan" data-title="GPS" data-language-autonym="贛語" data-language-local-name="Gan" class="interlanguage-link-target">贛語</a></li><li class="interlanguage-link interwiki-ki mw-list-item"><a href="https://ki.wikipedia.org/wiki/GPS" title="GPS – Kikuyu" lang="ki" hreflang="ki" data-title="GPS" data-language-autonym="Gĩkũyũ" data-language-local-name="Kikuyu" class="interlanguage-link-target">Gĩkũyũ</a></li><li class="interlanguage-link interwiki-gu mw-list-item"><a href="https://gu.wikipedia.org/wiki/%E0%AA%B5%E0%AB%88%E0%AA%B6%E0%AB%8D%E0%AA%B5%E0%AA%BF%E0%AA%95_%E0%AA%B8%E0%AB%8D%E0%AA%A5%E0%AA%B3%E0%AA%A8%E0%AA%BF%E0%AA%B0%E0%AB%8D%E0%AA%A7%E0%AA%BE%E0%AA%B0%E0%AA%A3_%E0%AA%AA%E0%AB%8D%E0%AA%B0%E0%AA%A3%E0%AA%BE%E0%AA%B2%E0%AB%80" title="વૈશ્વિક સ્થળનિર્ધારણ પ્રણાલી – Gujarati" lang="gu" hreflang="gu" data-title="વૈશ્વિક સ્થળનિર્ધારણ પ્રણાલી" data-language-autonym="ગુજરાતી" data-language-local-name="Gujarati" class="interlanguage-link-target">ગુજરાતી</a></li><li class="interlanguage-link interwiki-hak mw-list-item"><a href="https://hak.wikipedia.org/wiki/Chhi%C3%B2n-khi%C3%B9_Thin-vi_H%C3%AC-th%C3%BAng" title="Chhiòn-khiù Thin-vi Hì-thúng – Hakka Chinese" lang="hak" hreflang="hak" data-title="Chhiòn-khiù Thin-vi Hì-thúng" data-language-autonym="客家語 / Hak-kâ-ngî" data-language-local-name="Hakka Chinese" class="interlanguage-link-target">客家語 / Hak-kâ-ngî</a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/GPS" title="GPS – Korean" lang="ko" hreflang="ko" data-title="GPS" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target">한국어</a></li><li class="interlanguage-link interwiki-ha mw-list-item"><a href="https://ha.wikipedia.org/wiki/Tsarin_Matsayin_Duniya" title="Tsarin Matsayin Duniya – Hausa" lang="ha" hreflang="ha" data-title="Tsarin Matsayin Duniya" data-language-autonym="Hausa" data-language-local-name="Hausa" class="interlanguage-link-target">Hausa</a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D4%B3%D5%AC%D5%B8%D5%A2%D5%A1%D5%AC_%D5%BF%D5%A5%D5%B2%D5%B8%D6%80%D5%B8%D5%B7%D5%B4%D5%A1%D5%B6_%D5%B0%D5%A1%D5%B4%D5%A1%D5%AF%D5%A1%D6%80%D5%A3" title="Գլոբալ տեղորոշման համակարգ – Armenian" lang="hy" hreflang="hy" data-title="Գլոբալ տեղորոշման համակարգ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target">Հայերեն</a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%B5%E0%A5%88%E0%A4%B6%E0%A5%8D%E0%A4%B5%E0%A4%BF%E0%A4%95_%E0%A4%B8%E0%A5%8D%E0%A4%A5%E0%A4%BE%E0%A4%A8-%E0%A4%A8%E0%A4%BF%E0%A4%B0%E0%A5%8D%E0%A4%A7%E0%A4%BE%E0%A4%B0%E0%A4%A3_%E0%A4%AA%E0%A5%8D%E0%A4%B0%E0%A4%A3%E0%A4%BE%E0%A4%B2%E0%A5%80" title="वैश्विक स्थान-निर्धारण प्रणाली – Hindi" lang="hi" hreflang="hi" data-title="वैश्विक स्थान-निर्धारण प्रणाली" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target">हिन्दी</a></li><li class="interlanguage-link interwiki-hr badge-Q17437796 badge-featuredarticle mw-list-item" title="featured article badge"><a href="https://hr.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Croatian" lang="hr" hreflang="hr" data-title="Global Positioning System" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target">Hrvatski</a></li><li class="interlanguage-link interwiki-ig mw-list-item"><a href="https://ig.wikipedia.org/wiki/Usoro_Nhazi_%E1%BB%A4wa" title="Usoro Nhazi Ụwa – Igbo" lang="ig" hreflang="ig" data-title="Usoro Nhazi Ụwa" data-language-autonym="Igbo" data-language-local-name="Igbo" class="interlanguage-link-target">Igbo</a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Sistem_Pemosisi_Global" title="Sistem Pemosisi Global – Indonesian" lang="id" hreflang="id" data-title="Sistem Pemosisi Global" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target">Bahasa Indonesia</a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Icelandic" lang="is" hreflang="is" data-title="Global Positioning System" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target">Íslenska</a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/GPS" title="GPS – Italian" lang="it" hreflang="it" data-title="GPS" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target">Italiano</a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/GPS" title="GPS – Hebrew" lang="he" hreflang="he" data-title="GPS" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target">עברית</a></li><li class="interlanguage-link interwiki-jv mw-list-item"><a href="https://jv.wikipedia.org/wiki/Sistem_Posisi_Global" title="Sistem Posisi Global – Javanese" lang="jv" hreflang="jv" data-title="Sistem Posisi Global" data-language-autonym="Jawa" data-language-local-name="Javanese" class="interlanguage-link-target">Jawa</a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%9C%E0%B2%BF%E0%B2%AA%E0%B2%BF%E0%B2%8E%E0%B2%B8%E0%B3%8D" title="ಜಿಪಿಎಸ್ – Kannada" lang="kn" hreflang="kn" data-title="ಜಿಪಿಎಸ್" data-language-autonym="ಕನ್ನಡ" data-language-local-name="Kannada" class="interlanguage-link-target">ಕನ್ನಡ</a></li><li class="interlanguage-link interwiki-pam mw-list-item"><a href="https://pam.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Pampanga" lang="pam" hreflang="pam" data-title="Global Positioning System" data-language-autonym="Kapampangan" data-language-local-name="Pampanga" class="interlanguage-link-target">Kapampangan</a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%92%E1%83%9A%E1%83%9D%E1%83%91%E1%83%90%E1%83%9A%E1%83%A3%E1%83%A0%E1%83%98_%E1%83%90%E1%83%93%E1%83%92%E1%83%98%E1%83%9A%E1%83%9B%E1%83%93%E1%83%94%E1%83%91%E1%83%90%E1%83%A0%E1%83%94%E1%83%9D%E1%83%91%E1%83%98%E1%83%A1_%E1%83%92%E1%83%90%E1%83%9C%E1%83%9B%E1%83%A1%E1%83%90%E1%83%96%E1%83%A6%E1%83%95%E1%83%A0%E1%83%94%E1%83%9A%E1%83%98_%E1%83%A1%E1%83%98%E1%83%A1%E1%83%A2%E1%83%94%E1%83%9B%E1%83%90" title="გლობალური ადგილმდებარეობის განმსაზღვრელი სისტემა – Georgian" lang="ka" hreflang="ka" data-title="გლობალური ადგილმდებარეობის განმსაზღვრელი სისტემა" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target">ქართული</a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/GPS" title="GPS – Kazakh" lang="kk" hreflang="kk" data-title="GPS" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target">Қазақша</a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Swahili" lang="sw" hreflang="sw" data-title="Global Positioning System" data-language-autonym="Kiswahili" data-language-local-name="Swahili" class="interlanguage-link-target">Kiswahili</a></li><li class="interlanguage-link interwiki-ht mw-list-item"><a href="https://ht.wikipedia.org/wiki/Sist%C3%A8m_pozisyon_global" title="Sistèm pozisyon global – Haitian Creole" lang="ht" hreflang="ht" data-title="Sistèm pozisyon global" data-language-autonym="Kreyòl ayisyen" data-language-local-name="Haitian Creole" class="interlanguage-link-target">Kreyòl ayisyen</a></li><li class="interlanguage-link interwiki-gcr mw-list-item"><a href="https://gcr.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Guianan Creole" lang="gcr" hreflang="gcr" data-title="Global Positioning System" data-language-autonym="Kriyòl gwiyannen" data-language-local-name="Guianan Creole" class="interlanguage-link-target">Kriyòl gwiyannen</a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/GPS" title="GPS – Kurdish" lang="ku" hreflang="ku" data-title="GPS" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target">Kurdî</a></li><li class="interlanguage-link interwiki-lo mw-list-item"><a href="https://lo.wikipedia.org/wiki/%E0%BA%A5%E0%BA%B0%E0%BA%9A%E0%BA%BB%E0%BA%9A%E0%BA%81%E0%BA%B2%E0%BA%99%E0%BA%88%E0%BA%B1%E0%BA%94%E0%BA%95%E0%BB%8D%E0%BA%B2%E0%BB%81%E0%BA%AB%E0%BA%99%E0%BB%88%E0%BA%87%E0%BA%97%E0%BA%BB%E0%BB%88%E0%BA%A7%E0%BB%82%E0%BA%A5%E0%BA%81" title="ລະບົບການຈັດຕໍາແຫນ່ງທົ່ວໂລກ – Lao" lang="lo" hreflang="lo" data-title="ລະບົບການຈັດຕໍາແຫນ່ງທົ່ວໂລກ" data-language-autonym="ລາວ" data-language-local-name="Lao" class="interlanguage-link-target">ລາວ</a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/GPS_(Systema_localizationis_globale)" title="GPS (Systema localizationis globale) – Latin" lang="la" hreflang="la" data-title="GPS (Systema localizationis globale)" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target">Latina</a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Glob%C4%81l%C4%81_pozicion%C4%93%C5%A1anas_sist%C4%93ma" title="Globālā pozicionēšanas sistēma – Latvian" lang="lv" hreflang="lv" data-title="Globālā pozicionēšanas sistēma" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target">Latviešu</a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Luxembourgish" lang="lb" hreflang="lb" data-title="Global Positioning System" data-language-autonym="Lëtzebuergesch" data-language-local-name="Luxembourgish" class="interlanguage-link-target">Lëtzebuergesch</a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/GPS" title="GPS – Lithuanian" lang="lt" hreflang="lt" data-title="GPS" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target">Lietuvių</a></li><li class="interlanguage-link interwiki-ln mw-list-item"><a href="https://ln.wikipedia.org/wiki/GPS" title="GPS – Lingala" lang="ln" hreflang="ln" data-title="GPS" data-language-autonym="Lingála" data-language-local-name="Lingala" class="interlanguage-link-target">Lingála</a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/Sist%C3%A8ma_global_de_rilevament_de_la_posizion" title="Sistèma global de rilevament de la posizion – Lombard" lang="lmo" hreflang="lmo" data-title="Sistèma global de rilevament de la posizion" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target">Lombard</a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Hungarian" lang="hu" hreflang="hu" data-title="Global Positioning System" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target">Magyar</a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%93%D0%9F%D0%A1" title="ГПС – Macedonian" lang="mk" hreflang="mk" data-title="ГПС" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target">Македонски</a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%97%E0%B5%8D%E0%B4%B2%E0%B5%8B%E0%B4%AC%E0%B5%BD_%E0%B4%AA%E0%B5%8A%E0%B4%B8%E0%B4%BF%E0%B4%B7%E0%B4%A8%E0%B4%BF%E0%B4%99%E0%B5%8D_%E0%B4%B8%E0%B4%BF%E0%B4%B8%E0%B5%8D%E0%B4%B1%E0%B5%8D%E0%B4%B1%E0%B4%82" title="ഗ്ലോബൽ പൊസിഷനിങ് സിസ്റ്റം – Malayalam" lang="ml" hreflang="ml" data-title="ഗ്ലോബൽ പൊസിഷനിങ് സിസ്റ്റം" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target">മലയാളം</a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%97%E0%A5%8D%E0%A4%B2%E0%A5%8B%E0%A4%AC%E0%A4%B2_%E0%A4%AA%E0%A5%8B%E0%A4%9D%E0%A4%BF%E0%A4%B6%E0%A4%A8%E0%A4%BF%E0%A4%82%E0%A4%97_%E0%A4%B8%E0%A4%BF%E0%A4%B8%E0%A5%8D%E0%A4%9F%E0%A5%80%E0%A4%AE" title="ग्लोबल पोझिशनिंग सिस्टीम – Marathi" lang="mr" hreflang="mr" data-title="ग्लोबल पोझिशनिंग सिस्टीम" data-language-autonym="मराठी" data-language-local-name="Marathi" class="interlanguage-link-target">मराठी</a></li><li class="interlanguage-link interwiki-xmf mw-list-item"><a href="https://xmf.wikipedia.org/wiki/GPS" title="GPS – Mingrelian" lang="xmf" hreflang="xmf" data-title="GPS" data-language-autonym="მარგალური" data-language-local-name="Mingrelian" class="interlanguage-link-target">მარგალური</a></li><li class="interlanguage-link interwiki-arz mw-list-item"><a href="https://arz.wikipedia.org/wiki/%D8%AC%DB%8C_%D8%A8%DB%8C_%D8%A7%D8%B3" title="جی بی اس – Egyptian Arabic" lang="arz" hreflang="arz" data-title="جی بی اس" data-language-autonym="مصرى" data-language-local-name="Egyptian Arabic" class="interlanguage-link-target">مصرى</a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Sistem_Kedudukan_Sejagat" title="Sistem Kedudukan Sejagat – Malay" lang="ms" hreflang="ms" data-title="Sistem Kedudukan Sejagat" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target">Bahasa Melayu</a></li><li class="interlanguage-link interwiki-min mw-list-item"><a href="https://min.wikipedia.org/wiki/Sistem_Pamosisi_Global" title="Sistem Pamosisi Global – Minangkabau" lang="min" hreflang="min" data-title="Sistem Pamosisi Global" data-language-autonym="Minangkabau" data-language-local-name="Minangkabau" class="interlanguage-link-target">Minangkabau</a></li><li class="interlanguage-link interwiki-mwl mw-list-item"><a href="https://mwl.wikipedia.org/wiki/Sistema_de_Posicionamiento_Global" title="Sistema de Posicionamiento Global – Mirandese" lang="mwl" hreflang="mwl" data-title="Sistema de Posicionamiento Global" data-language-autonym="Mirandés" data-language-local-name="Mirandese" class="interlanguage-link-target">Mirandés</a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Mongolian" lang="mn" hreflang="mn" data-title="Global Positioning System" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target">Монгол</a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/%E1%80%82%E1%80%BB%E1%80%AE%E1%80%95%E1%80%AE%E1%80%A1%E1%80%80%E1%80%BA%E1%80%85%E1%80%BA" title="ဂျီပီအက်စ် – Burmese" lang="my" hreflang="my" data-title="ဂျီပီအက်စ်" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target">မြန်မာဘာသာ</a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Global_positioning_system" title="Global positioning system – Dutch" lang="nl" hreflang="nl" data-title="Global positioning system" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target">Nederlands</a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%82%B0%E3%83%AD%E3%83%BC%E3%83%90%E3%83%AB%E3%83%BB%E3%83%9D%E3%82%B8%E3%82%B7%E3%83%A7%E3%83%8B%E3%83%B3%E3%82%B0%E3%83%BB%E3%82%B7%E3%82%B9%E3%83%86%E3%83%A0" title="グローバル・ポジショニング・システム – Japanese" lang="ja" hreflang="ja" data-title="グローバル・ポジショニング・システム" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target">日本語</a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Global Positioning System" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target">Norsk bokmål</a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Global Positioning System" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target">Norsk nynorsk</a></li><li class="interlanguage-link interwiki-nrm mw-list-item"><a href="https://nrm.wikipedia.org/wiki/Pliaich%27chie_globale_%C3%A0_satellite" title="Pliaich'chie globale à satellite – Norman" lang="nrf" hreflang="nrf" data-title="Pliaich'chie globale à satellite" data-language-autonym="Nouormand" data-language-local-name="Norman" class="interlanguage-link-target">Nouormand</a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Sist%C3%A8ma_de_posicionament_global" title="Sistèma de posicionament global – Occitan" lang="oc" hreflang="oc" data-title="Sistèma de posicionament global" data-language-autonym="Occitan" data-language-local-name="Occitan" class="interlanguage-link-target">Occitan</a></li><li class="interlanguage-link interwiki-om mw-list-item"><a href="https://om.wikipedia.org/wiki/Sirna_Argama_Addunyaa" title="Sirna Argama Addunyaa – Oromo" lang="om" hreflang="om" data-title="Sirna Argama Addunyaa" data-language-autonym="Oromoo" data-language-local-name="Oromo" class="interlanguage-link-target">Oromoo</a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/Global_joylashuv_tizimi" title="Global joylashuv tizimi – Uzbek" lang="uz" hreflang="uz" data-title="Global joylashuv tizimi" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target">Oʻzbekcha / ўзбекча</a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%9C%E0%A9%80_%E0%A8%AA%E0%A9%80_%E0%A8%90%E0%A9%B1%E0%A8%B8" title="ਜੀ ਪੀ ਐੱਸ – Punjabi" lang="pa" hreflang="pa" data-title="ਜੀ ਪੀ ਐੱਸ" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="Punjabi" class="interlanguage-link-target">ਪੰਜਾਬੀ</a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%D8%AC%DB%8C_%D9%BE%DB%8C_%D8%A7%DB%8C%D8%B3" title="جی پی ایس – Western Punjabi" lang="pnb" hreflang="pnb" data-title="جی پی ایس" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target">پنجابی</a></li><li class="interlanguage-link interwiki-ps mw-list-item"><a href="https://ps.wikipedia.org/wiki/%D8%AF_%D9%84%D9%88%D8%B1_%D9%85%D9%88%D9%86%D8%AF%D9%86%DB%90_%D9%86%DA%93%D9%8A%D9%88%D8%A7%D9%84_%D8%BA%D9%88%D9%86%DA%89%D8%A7%D9%84" title="د لور موندنې نړيوال غونډال – Pashto" lang="ps" hreflang="ps" data-title="د لور موندنې نړيوال غونډال" data-language-autonym="پښتو" data-language-local-name="Pashto" class="interlanguage-link-target">پښتو</a></li><li class="interlanguage-link interwiki-jam mw-list-item"><a href="https://jam.wikipedia.org/wiki/Gluobal_Pozishanin_Sistim" title="Gluobal Pozishanin Sistim – Jamaican Creole English" lang="jam" hreflang="jam" data-title="Gluobal Pozishanin Sistim" data-language-autonym="Patois" data-language-local-name="Jamaican Creole English" class="interlanguage-link-target">Patois</a></li><li class="interlanguage-link interwiki-km mw-list-item"><a href="https://km.wikipedia.org/wiki/%E1%9E%94%E1%9F%92%E1%9E%9A%E1%9E%96%E1%9F%90%E1%9E%93%E1%9F%92%E1%9E%92%E1%9E%80%E1%9F%86%E1%9E%8E%E1%9E%8F%E1%9F%8B%E1%9E%91%E1%9E%B8%E1%9E%8F%E1%9E%B6%E1%9F%86%E1%9E%84%E1%9E%9F%E1%9E%80%E1%9E%9B" title="ប្រព័ន្ធកំណត់ទីតាំងសកល – Khmer" lang="km" hreflang="km" data-title="ប្រព័ន្ធកំណត់ទីតាំងសកល" data-language-autonym="ភាសាខ្មែរ" data-language-local-name="Khmer" class="interlanguage-link-target">ភាសាខ្មែរ</a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Polish" lang="pl" hreflang="pl" data-title="Global Positioning System" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target">Polski</a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Sistema_de_posicionamento_global" title="Sistema de posicionamento global – Portuguese" lang="pt" hreflang="pt" data-title="Sistema de posicionamento global" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target">Português</a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Romanian" lang="ro" hreflang="ro" data-title="Global Positioning System" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target">Română</a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/GPS" title="GPS – Russian" lang="ru" hreflang="ru" data-title="GPS" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target">Русский</a></li><li class="interlanguage-link interwiki-sa mw-list-item"><a href="https://sa.wikipedia.org/wiki/%E0%A4%B5%E0%A5%88%E0%A4%B6%E0%A5%8D%E0%A4%B5%E0%A4%BF%E0%A4%95%E0%A4%B8%E0%A5%8D%E0%A4%A5%E0%A4%BF%E0%A4%A4%E0%A4%BF%E0%A4%B8%E0%A5%82%E0%A4%9A%E0%A4%95%E0%A4%AA%E0%A4%A6%E0%A5%8D%E0%A4%A7%E0%A4%A4%E0%A4%BF%E0%A4%83" title="वैश्विकस्थितिसूचकपद्धतिः – Sanskrit" lang="sa" hreflang="sa" data-title="वैश्विकस्थितिसूचकपद्धतिः" data-language-autonym="संस्कृतम्" data-language-local-name="Sanskrit" class="interlanguage-link-target">संस्कृतम्</a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Scots" lang="sco" hreflang="sco" data-title="Global Positioning System" data-language-autonym="Scots" data-language-local-name="Scots" class="interlanguage-link-target">Scots</a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/Sistemi_i_Pozicionimit_Global" title="Sistemi i Pozicionimit Global – Albanian" lang="sq" hreflang="sq" data-title="Sistemi i Pozicionimit Global" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target">Shqip</a></li><li class="interlanguage-link interwiki-si mw-list-item"><a href="https://si.wikipedia.org/wiki/%E0%B6%9C%E0%B7%9D%E0%B6%BD%E0%B7%93%E0%B6%BA_%E0%B7%83%E0%B7%8A%E0%B6%AE%E0%B7%8F%E0%B6%B1_%E0%B6%B1%E0%B7%92%E0%B6%BB%E0%B7%8A%E0%B6%AB%E0%B6%BA%E0%B6%B1_%E0%B6%B4%E0%B6%AF%E0%B7%8A%E0%B6%B0%E0%B6%AD%E0%B7%92%E0%B6%BA" title="ගෝලීය ස්ථාන නිර්ණයන පද්ධතිය – Sinhala" lang="si" hreflang="si" data-title="ගෝලීය ස්ථාන නිර්ණයන පද්ධතිය" data-language-autonym="සිංහල" data-language-local-name="Sinhala" class="interlanguage-link-target">සිංහල</a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Simple English" lang="en-simple" hreflang="en-simple" data-title="Global Positioning System" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target">Simple English</a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Glob%C3%A1lny_lokaliza%C4%8Dn%C3%BD_syst%C3%A9m" title="Globálny lokalizačný systém – Slovak" lang="sk" hreflang="sk" data-title="Globálny lokalizačný systém" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target">Slovenčina</a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Globalni_sistem_pozicioniranja" title="Globalni sistem pozicioniranja – Slovenian" lang="sl" hreflang="sl" data-title="Globalni sistem pozicioniranja" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target">Slovenščina</a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%D8%B3%DB%8C%D8%B3%D8%AA%D9%85%DB%8C_%D8%B4%D9%88%DB%8E%D9%86%D8%AF%DB%86%D8%B2%DB%8C%DB%8C_%D8%AC%DB%8C%DA%BE%D8%A7%D9%86%DB%8C" title="سیستمی شوێندۆزیی جیھانی – Central Kurdish" lang="ckb" hreflang="ckb" data-title="سیستمی شوێندۆزیی جیھانی" data-language-autonym="کوردی" data-language-local-name="Central Kurdish" class="interlanguage-link-target">کوردی</a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/Globalni_pozicioni_sistem" title="Globalni pozicioni sistem – Serbian" lang="sr" hreflang="sr" data-title="Globalni pozicioni sistem" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target">Српски / srpski</a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Global Positioning System" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target">Srpskohrvatski / српскохрватски</a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/GPS" title="GPS – Finnish" lang="fi" hreflang="fi" data-title="GPS" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target">Suomi</a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Swedish" lang="sv" hreflang="sv" data-title="Global Positioning System" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target">Svenska</a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%AA%E0%AF%81%E0%AE%B5%E0%AE%BF%E0%AE%AF%E0%AE%BF%E0%AE%9F%E0%AE%99%E0%AF%8D%E0%AE%95%E0%AE%BE%E0%AE%9F%E0%AF%8D%E0%AE%9F%E0%AE%BF" title="புவியிடங்காட்டி – Tamil" lang="ta" hreflang="ta" data-title="புவியிடங்காட்டி" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target">தமிழ்</a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/GPS" title="GPS – Tatar" lang="tt" hreflang="tt" data-title="GPS" data-language-autonym="Татарча / tatarça" data-language-local-name="Tatar" class="interlanguage-link-target">Татарча / tatarça</a></li><li class="interlanguage-link interwiki-te mw-list-item"><a href="https://te.wikipedia.org/wiki/%E0%B0%9C%E0%B1%80%E0%B0%AA%E0%B1%80%E0%B0%AF%E0%B0%B8%E0%B1%8D" title="జీపీయస్ – Telugu" lang="te" hreflang="te" data-title="జీపీయస్" data-language-autonym="తెలుగు" data-language-local-name="Telugu" class="interlanguage-link-target">తెలుగు</a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B8%A3%E0%B8%B0%E0%B8%9A%E0%B8%9A%E0%B8%81%E0%B8%B3%E0%B8%AB%E0%B8%99%E0%B8%94%E0%B8%95%E0%B8%B3%E0%B9%81%E0%B8%AB%E0%B8%99%E0%B9%88%E0%B8%87%E0%B8%9A%E0%B8%99%E0%B9%82%E0%B8%A5%E0%B8%81" title="ระบบกำหนดตำแหน่งบนโลก – Thai" lang="th" hreflang="th" data-title="ระบบกำหนดตำแหน่งบนโลก" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target">ไทย</a></li><li class="interlanguage-link interwiki-tg mw-list-item"><a href="https://tg.wikipedia.org/wiki/GPS" title="GPS – Tajik" lang="tg" hreflang="tg" data-title="GPS" data-language-autonym="Тоҷикӣ" data-language-local-name="Tajik" class="interlanguage-link-target">Тоҷикӣ</a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/GPS" title="GPS – Turkish" lang="tr" hreflang="tr" data-title="GPS" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target">Türkçe</a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/GPS" title="GPS – Ukrainian" lang="uk" hreflang="uk" data-title="GPS" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target">Українська</a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D8%B9%D8%A7%D9%84%D9%85%DB%8C_%D9%85%D9%82%D8%A7%D9%85%DB%8C%D8%A7%D8%A8%DB%8C_%D9%86%D8%B8%D8%A7%D9%85" title="عالمی مقامیابی نظام – Urdu" lang="ur" hreflang="ur" data-title="عالمی مقامیابی نظام" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target">اردو</a></li><li class="interlanguage-link interwiki-ug mw-list-item"><a href="https://ug.wikipedia.org/wiki/%D9%8A%DB%95%D8%B1%D8%B4%D8%A7%D8%B1%D9%89_%D8%A6%D9%88%D8%B1%DB%87%D9%86_%D8%A8%DB%95%D9%84%DA%AF%D9%89%D9%84%DB%95%D8%B4_%D8%B3%D9%89%D8%B3%D8%AA%DB%90%D9%85%D9%89%D8%B3%D9%89" title="يەرشارى ئورۇن بەلگىلەش سىستېمىسى – Uyghur" lang="ug" hreflang="ug" data-title="يەرشارى ئورۇن بەلگىلەش سىستېمىسى" data-language-autonym="ئۇيغۇرچە / Uyghurche" data-language-local-name="Uyghur" class="interlanguage-link-target">ئۇيغۇرچە / Uyghurche</a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/GPS" title="GPS – Vietnamese" lang="vi" hreflang="vi" data-title="GPS" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target">Tiếng Việt</a></li><li class="interlanguage-link interwiki-guc mw-list-item"><a href="https://guc.wikipedia.org/wiki/Akuwa%27ipaa_eejat%C3%BClee_mmanain" title="Akuwa'ipaa eejatülee mmanain – Wayuu" lang="guc" hreflang="guc" data-title="Akuwa'ipaa eejatülee mmanain" data-language-autonym="Wayuunaiki" data-language-local-name="Wayuu" class="interlanguage-link-target">Wayuunaiki</a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%E5%85%A8%E7%90%83%E5%AE%9A%E4%BD%8D%E7%B3%BB%E7%BB%9F" title="全球定位系统 – Wu" lang="wuu" hreflang="wuu" data-title="全球定位系统" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target">吴语</a></li><li class="interlanguage-link interwiki-yi mw-list-item"><a href="https://yi.wikipedia.org/wiki/GPS" title="GPS – Yiddish" lang="yi" hreflang="yi" data-title="GPS" data-language-autonym="ייִדיש" data-language-local-name="Yiddish" class="interlanguage-link-target">ייִדיש</a></li><li class="interlanguage-link interwiki-yo mw-list-item"><a href="https://yo.wikipedia.org/wiki/Global_Positioning_System" title="Global Positioning System – Yoruba" lang="yo" hreflang="yo" data-title="Global Positioning System" data-language-autonym="Yorùbá" 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i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">This article is about the American global navigation satellite system. For similar systems, see <a href="/wiki/Satellite_navigation" title="Satellite navigation">Satellite navigation</a>.</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">"GPS" redirects here. For GPS devices, see <a href="/wiki/Satellite_navigation_device" title="Satellite navigation device">Satellite navigation device</a>. For other uses, see <a href="/wiki/GPS_(disambiguation)" class="mw-disambig" title="GPS (disambiguation)">GPS (disambiguation)</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox" style="width:22em;"><caption class="infobox-title">Global Positioning System (GPS)</caption><tbody><tr><td colspan="2" class="infobox-image"><a href="/wiki/File:NAVSTAR_GPS_logo.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3c/NAVSTAR_GPS_logo.png/260px-NAVSTAR_GPS_logo.png" decoding="async" width="260" height="239" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/3/3c/NAVSTAR_GPS_logo.png 1.5x" data-file-width="291" data-file-height="267" /></a><div class="infobox-caption">GPS Logo </div></td></tr><tr><th scope="row" class="infobox-label">Country/ies of origin</th><td class="infobox-data">United States</td></tr><tr><th scope="row" class="infobox-label">Operator(s)</th><td class="infobox-data"><a href="/wiki/United_States_Space_Force" title="United States Space Force">US Space Force</a> (<a href="/wiki/Mission_Delta_31" title="Mission Delta 31">Mission Delta 31</a>)</td></tr><tr><th scope="row" class="infobox-label">Type</th><td class="infobox-data">Military, civilian</td></tr><tr><th scope="row" class="infobox-label">Status</th><td class="infobox-data">Operational</td></tr><tr><th scope="row" class="infobox-label">Coverage</th><td class="infobox-data">Global</td></tr><tr><th scope="row" class="infobox-label">Accuracy</th><td class="infobox-data">30–500 cm (0.98–16 ft)</td></tr><tr><th colspan="2" class="infobox-header">Constellation size</th></tr><tr><th scope="row" class="infobox-label"><abbr title="Intended number at full capacity">Nominal</abbr> satellites</th><td class="infobox-data">24</td></tr><tr><th scope="row" class="infobox-label"><abbr title="All healthy: Operational + Spare">Current usable</abbr> satellites</th><td class="infobox-data">31 operational</td></tr><tr><th scope="row" class="infobox-label">First launch</th><td class="infobox-data">February 22, 1978; 46 years ago (1978-02-22)</td></tr><tr><th scope="row" class="infobox-label">Total launches</th><td class="infobox-data">79</td></tr><tr><th colspan="2" class="infobox-header">Orbital characteristics</th></tr><tr><th scope="row" class="infobox-label">Regime(s)</th><td class="infobox-data">6 <a href="/wiki/Medium_Earth_orbit" title="Medium Earth orbit">MEO</a> planes</td></tr><tr><th scope="row" class="infobox-label">Orbital height</th><td class="infobox-data">20,180 km (12,540 mi)</td></tr><tr><th scope="row" class="infobox-label">Orbital period</th><td class="infobox-data"><style data-mw-deduplicate="TemplateStyles:r1154941027">.mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}</style>1⁄2 <a href="/wiki/Sidereal_day" class="mw-redirect" title="Sidereal day">sd</a> or 11 hours and 58 minutes</td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Satellite_revisit_period" title="Satellite revisit period">Revisit period</a></th><td class="infobox-data">1 sidereal day</td></tr><tr><th colspan="2" class="infobox-header">Other details</th></tr><tr><th scope="row" class="infobox-label">Cost</th><td class="infobox-data"><style data-mw-deduplicate="TemplateStyles:r1116488514">.mw-parser-output .treeview ul{padding:0;margin:0}.mw-parser-output .treeview li{padding:0;margin:0;list-style-type:none;list-style-image:none}.mw-parser-output .treeview li li{background:url("https://upload.wikimedia.org/wikipedia/commons/f/f2/Treeview-grey-line.png")no-repeat 0 -2981px;padding-left:21px;text-indent:0.3em}.mw-parser-output .treeview li li:last-child{background-position:0 -5971px}.mw-parser-output .treeview li.emptyline>ul>.mw-empty-elt:first-child+.emptyline,.mw-parser-output .treeview li.emptyline>ul>li:first-child{background-position:0 9px}</style><div class="treeview"> <ul><li>Initial constellation: <ul><li class="mw-empty-elt"></li><li class="emptyline"></li> <li>$12 billion<a href="#cite_note-time-gps-cost-1">[1]</a></li></ul></li></ul> </div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1116488514"><div class="treeview"> <ul><li>Operating cost: <ul><li class="mw-empty-elt"></li><li class="emptyline"></li> <li>$1.84 billion per year (2023)<a href="#cite_note-time-gps-cost-1">[1]</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="infobox-label">Website</th><td class="infobox-data"><a rel="nofollow" class="external text" href="https://www.gps.gov">gps.gov</a></td></tr></tbody></table> <style data-mw-deduplicate="TemplateStyles:r1237032888/mw-parser-output/.tmulti">.mw-parser-output .tmulti .multiimageinner{display:flex;flex-direction:column}.mw-parser-output .tmulti .trow{display:flex;flex-direction:row;clear:left;flex-wrap:wrap;width:100%;box-sizing:border-box}.mw-parser-output .tmulti .tsingle{margin:1px;float:left}.mw-parser-output .tmulti .theader{clear:both;font-weight:bold;text-align:center;align-self:center;background-color:transparent;width:100%}.mw-parser-output .tmulti .thumbcaption{background-color:transparent}.mw-parser-output .tmulti .text-align-left{text-align:left}.mw-parser-output .tmulti .text-align-right{text-align:right}.mw-parser-output .tmulti .text-align-center{text-align:center}@media all and (max-width:720px){.mw-parser-output .tmulti 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src="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/GPS_Block_IIIA.jpg/175px-GPS_Block_IIIA.jpg" decoding="async" width="175" height="175" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/49/GPS_Block_IIIA.jpg/263px-GPS_Block_IIIA.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/49/GPS_Block_IIIA.jpg/350px-GPS_Block_IIIA.jpg 2x" data-file-width="1500" data-file-height="1500" /></a></div><div class="thumbcaption">Artist's impression of GPS Block IIIA satellite in Earth orbit</div></div><div class="tsingle" style="width:177px;max-width:177px"><div class="thumbimage"><a href="/wiki/File:Magellan_GPS_Blazer12.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/68/Magellan_GPS_Blazer12.jpg/175px-Magellan_GPS_Blazer12.jpg" decoding="async" width="175" height="131" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/68/Magellan_GPS_Blazer12.jpg/263px-Magellan_GPS_Blazer12.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/68/Magellan_GPS_Blazer12.jpg/350px-Magellan_GPS_Blazer12.jpg 2x" data-file-width="2560" data-file-height="1920" /></a></div><div class="thumbcaption">Late 1990s civilian GPS receiver ("<a href="/wiki/GPS_navigation_device" class="mw-redirect" title="GPS navigation device">GPS navigation device</a>") in a marine application</div></div></div><div class="trow"><div class="tsingle" style="width:177px;max-width:177px"><div class="thumbimage"><a href="/wiki/File:KyotoTaxiRide.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/KyotoTaxiRide.jpg/175px-KyotoTaxiRide.jpg" decoding="async" width="175" height="117" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/KyotoTaxiRide.jpg/263px-KyotoTaxiRide.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8b/KyotoTaxiRide.jpg/350px-KyotoTaxiRide.jpg 2x" data-file-width="770" data-file-height="514" /></a></div><div class="thumbcaption"><a href="/wiki/Automotive_navigation_system" title="Automotive navigation system">Automotive navigation system</a> in a taxicab, 2000s</div></div><div class="tsingle" style="width:177px;max-width:177px"><div class="thumbimage"><a href="/wiki/File:2nd_Space_Operations_Squadron_(7033686).jpeg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/2nd_Space_Operations_Squadron_%287033686%29.jpeg/175px-2nd_Space_Operations_Squadron_%287033686%29.jpeg" decoding="async" width="175" height="140" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/2nd_Space_Operations_Squadron_%287033686%29.jpeg/263px-2nd_Space_Operations_Squadron_%287033686%29.jpeg 1.5x, 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.mw-parser-output .sidebar:not(.notheme) .sidebar-list-title,html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle a{color:var(--color-progressive)!important}}@media print{body.ns-0 .mw-parser-output .sidebar{display:none!important}}</style><table class="sidebar sidebar-collapse nomobile nowraplinks"><tbody><tr><th class="sidebar-title" style="padding-bottom:0.4em;"><a href="/wiki/Geodesy" title="Geodesy">Geodesy</a></th></tr><tr><td class="sidebar-image"><a href="/wiki/File:Globe_Atlantic.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Globe_Atlantic.svg/120px-Globe_Atlantic.svg.png" decoding="async" width="120" height="121" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Globe_Atlantic.svg/180px-Globe_Atlantic.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b1/Globe_Atlantic.svg/240px-Globe_Atlantic.svg.png 2x" data-file-width="717" data-file-height="721" /></a></td></tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)">Fundamentals</div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Geodesy" title="Geodesy">Geodesy</a></li> <li><a href="/wiki/Geodynamics" title="Geodynamics">Geodynamics</a></li> <li><a href="/wiki/Geomatics" title="Geomatics">Geomatics</a></li> <li><a href="/wiki/History_of_geodesy" title="History of geodesy">History</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)">Concepts</div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Geographical_distance" title="Geographical distance">Geographical distance</a></li> <li><a href="/wiki/Geoid" title="Geoid">Geoid</a></li> <li><a href="/wiki/Figure_of_the_Earth" title="Figure of the Earth">Figure of the Earth</a> (<a href="/wiki/Earth_radius" title="Earth radius">radius</a> and <a href="/wiki/Earth%27s_circumference" title="Earth's circumference">circumference</a>)</li> <li><a href="/wiki/Geodetic_coordinates" title="Geodetic coordinates">Geodetic coordinates</a></li> <li><a href="/wiki/Geodetic_datum" title="Geodetic datum">Geodetic datum</a></li> <li><a href="/wiki/Geodesic" title="Geodesic">Geodesic</a></li> <li><a href="/wiki/Horizontal_position_representation" title="Horizontal position representation">Horizontal position representation</a></li> <li><a href="/wiki/Latitude" title="Latitude">Latitude</a> / <a href="/wiki/Longitude" title="Longitude">Longitude</a></li> <li><a href="/wiki/Map_projection" title="Map projection">Map projection</a></li> <li><a href="/wiki/Reference_ellipsoid" class="mw-redirect" title="Reference ellipsoid">Reference ellipsoid</a></li> <li><a href="/wiki/Satellite_geodesy" title="Satellite geodesy">Satellite geodesy</a></li> <li><a href="/wiki/Spatial_reference_system" title="Spatial reference system">Spatial reference system</a></li> <li><a href="/wiki/Spatial_relation" title="Spatial relation">Spatial relations</a></li> <li><a href="/wiki/Vertical_position" title="Vertical position">Vertical positions</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)">Technologies</div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Satellite_navigation" title="Satellite navigation">Global Nav. Sat. Systems (GNSSs)</a></li> <li><a class="mw-selflink selflink">Global Pos. System (GPS)</a></li> <li><a href="/wiki/GLONASS" title="GLONASS">GLONASS (Russia)</a></li> <li><a href="/wiki/BeiDou" title="BeiDou">BeiDou (BDS) (China)</a></li> <li><a href="/wiki/Galileo_(satellite_navigation)" title="Galileo (satellite navigation)">Galileo (Europe)</a></li> <li><a href="/wiki/Indian_Regional_Navigation_Satellite_System" title="Indian Regional Navigation Satellite System">NAVIC (India)</a></li> <li><a href="/wiki/Quasi-Zenith_Satellite_System" title="Quasi-Zenith Satellite System">Quasi-Zenith Sat. Sys. (QZSS) (Japan)</a></li> <li><a href="/wiki/Discrete_Global_Grid" class="mw-redirect" title="Discrete Global Grid">Discrete Global Grid and Geocoding</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed plainlist"><div class="sidebar-list-title" style="color: var(--color-base)">Standards (history)</div><div class="sidebar-list-content mw-collapsible-content hlist"><table class="nowrap" style="width:100%;border-collapse:collapse;border-spacing:0px 0px;border:none;line-height:1.2em;"><tbody><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/Sea_Level_Datum_of_1929" class="mw-redirect" title="Sea Level Datum of 1929">NGVD 29</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> Sea Level Datum 1929</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/OSGB36" class="mw-redirect" title="OSGB36">OSGB36</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> Ordnance Survey Great Britain 1936</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/SK-42_reference_system" title="SK-42 reference system">SK-42</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> Systema Koordinat 1942 goda</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/ED50" title="ED50">ED50</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> European Datum 1950</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/South_American_Datum#SAD69" title="South American Datum">SAD69</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> South American Datum 1969</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/GRS_80" class="mw-redirect" title="GRS 80">GRS 80</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> Geodetic Reference System 1980</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/ISO_6709" title="ISO 6709">ISO 6709</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> Geographic point coord. 1983</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/North_American_Datum#North_American_Datum_of_1983" title="North American Datum">NAD 83</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> North American Datum 1983</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/World_Geodetic_System" title="World Geodetic System">WGS 84</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> World Geodetic System 1984</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/North_American_Vertical_Datum_of_1988" title="North American Vertical Datum of 1988">NAVD 88</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> N. American Vertical Datum 1988</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/European_Terrestrial_Reference_System_1989" title="European Terrestrial Reference System 1989">ETRS89</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> European Terrestrial Ref. Sys. 1989</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/Restrictions_on_geographic_data_in_China" title="Restrictions on geographic data in China">GCJ-02</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> Chinese obfuscated datum 2002</td></tr><tr style="vertical-align:top"><td style="text-align:left;padding-left:0.5em;"> <a href="/wiki/Geo_URI_scheme" title="Geo URI scheme">Geo URI</a></td><td style="text-align:right;font-size:90%;padding-right:0.55em;"> Internet link to a point 2010</td></tr></tbody></table> <ul><li><a href="/wiki/International_Terrestrial_Reference_System" class="mw-redirect" title="International Terrestrial Reference System">International Terrestrial Reference System</a></li> <li><a href="/wiki/SRID" class="mw-redirect" title="SRID">Spatial Reference System Identifier (SRID)</a></li> <li><a href="/wiki/Universal_Transverse_Mercator_coordinate_system" title="Universal Transverse Mercator coordinate system">Universal Transverse Mercator (UTM)</a></li></ul></div></div></td> </tr><tr><td class="sidebar-navbar"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Geodesy" title="Template:Geodesy"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Geodesy" title="Template talk:Geodesy"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Geodesy" title="Special:EditPage/Template:Geodesy"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> The Global Positioning System (GPS), originally Navstar GPS,<a href="#cite_note-2">[2]</a> is a <a href="/wiki/Radionavigation-satellite_service" class="mw-redirect" title="Radionavigation-satellite service">satellite-based radio navigation</a> system owned by the <a href="/wiki/United_States_Space_Force" title="United States Space Force">United States Space Force</a> and operated by <a href="/wiki/Mission_Delta_31" title="Mission Delta 31">Mission Delta 31</a>.<a href="#cite_note-:0-3">[3]</a> It is one of the <a href="/wiki/Satellite_navigation" title="Satellite navigation">global navigation satellite systems</a> (GNSS) that provide <a href="/wiki/Geolocation" class="mw-redirect" title="Geolocation">geolocation</a> and <a href="/wiki/Time_transfer" class="mw-redirect" title="Time transfer">time information</a> to a <a href="/wiki/Satellite_navigation_device" title="Satellite navigation device">GPS receiver</a> anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.<a href="#cite_note-4">[4]</a> It does not require the user to transmit any data, and operates independently of any telephone or Internet reception, though these technologies can enhance the usefulness of the GPS positioning information. It provides critical positioning capabilities to military, civil, and commercial users around the world. Although the United States government created, controls, and maintains the GPS system, it is freely accessible to anyone with a GPS receiver.<a href="#cite_note-5">[5]</a> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Overview">Overview</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=1" title="Edit section: Overview">edit</a>]</div> The GPS project was started by the <a href="/wiki/United_States_Department_of_Defense" title="United States Department of Defense">U.S. Department of Defense</a> in 1973. The first prototype spacecraft was launched in 1978 and the full constellation of 24 satellites became operational in 1993. After <a href="/wiki/Korean_Air_Lines_Flight_007" title="Korean Air Lines Flight 007">Korean Air Lines Flight 007</a> was shot down when it mistakenly entered Soviet airspace, President <a href="/wiki/Ronald_Reagan" title="Ronald Reagan">Ronald Reagan</a> announced that the GPS system would be made available for civilian use as of September 16, 1983;<a href="#cite_note-6">[6]</a> however, initially this civilian use was limited to an average accuracy of 100 meters (330 ft) by use of <a href="/wiki/Error_analysis_for_the_Global_Positioning_System#Selective_availability" title="Error analysis for the Global Positioning System">Selective Availability</a> (SA), a deliberate error introduced into the GPS data that military receivers could correct for. As civilian GPS usage grew, there was increasing pressure to remove this error. The SA system was temporarily disabled during the <a href="/wiki/Gulf_War" title="Gulf War">Gulf War</a>, as a shortage of military GPS units meant that many US soldiers were using civilian GPS units sent from home. In the 1990s, <a href="/wiki/Differential_GPS" title="Differential GPS">Differential GPS</a> systems from the <a href="/wiki/US_Coast_Guard" class="mw-redirect" title="US Coast Guard">US Coast Guard</a>, <a href="/wiki/Federal_Aviation_Administration" title="Federal Aviation Administration">Federal Aviation Administration</a>, and similar agencies in other countries began to broadcast local GPS corrections, reducing the effect of both SA degradation and atmospheric effects (that military receivers also corrected for). The U.S. military had also developed methods to perform local GPS jamming, meaning that the ability to globally degrade the system was no longer necessary. As a result, United States President <a href="/wiki/Bill_Clinton" title="Bill Clinton">Bill Clinton</a> signed a bill ordering that Selective Availability be disabled on May 1, 2000;<a href="#cite_note-gpsgovaccurary-7">[7]</a> and, in <a href="/wiki/2007" title="2007">2007</a>, the US government announced that the next generation of GPS satellites would not include the feature at all. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of <a href="/wiki/GPS_Block_III" title="GPS Block III">GPS Block III</a> satellites and Next Generation Operational Control System (OCX)<a href="#cite_note-losangelesmil-8">[8]</a> which was authorized by the <a href="/wiki/United_States_Congress" title="United States Congress">U.S. Congress</a> in 2000. When Selective Availability was discontinued, GPS was accurate to about 5 meters (16 ft). GPS receivers that use the L5 band have much higher accuracy of 30 centimeters (12 in), while those for high-end applications such as engineering and land surveying are accurate to within <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027">2 cm (3⁄4 in) and can even provide sub-millimeter accuracy with long-term measurements.<a href="#cite_note-gpsgovaccurary-7">[7]</a><a href="#cite_note-9">[9]</a><a href="#cite_note-10">[10]</a> Consumer devices such as smartphones can be accurate to 4.9 m (16 ft) or better when used with assistive services like <a href="/wiki/Wi-Fi_positioning_system" title="Wi-Fi positioning system">Wi-Fi positioning</a>.<a href="#cite_note-11">[11]</a> As of July 2023<a class="external text" href="https://en.wikipedia.org/w/index.php?title=Global_Positioning_System&action=edit">[update]</a>, 18 GPS satellites broadcast L5 signals, which are considered pre-operational prior to being broadcast by a full complement of 24 satellites in 2027.<a href="#cite_note-12">[12]</a> <div class="mw-heading mw-heading2"><h2 id="History">History</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=2" title="Edit section: History">edit</a>]</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><video id="mwe_player_0" poster="//upload.wikimedia.org/wikipedia/commons/thumb/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv/220px--AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="220" height="165" data-durationhint="80" data-mwtitle="AFSC_Film,_NAVSTAR_GPS-Circa_1977.ogv" data-mwprovider="wikimediacommons" resource="/wiki/File:AFSC_Film,_NAVSTAR_GPS-Circa_1977.ogv"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv.480p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="480p.vp9.webm" data-width="640" data-height="480" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv.720p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="720p.vp9.webm" data-width="960" data-height="720" /><source src="//upload.wikimedia.org/wikipedia/commons/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv" type="video/ogg; codecs="theora, vorbis"" data-width="960" data-height="720" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv.144p.mjpeg.mov" type="video/quicktime" data-transcodekey="144p.mjpeg.mov" data-width="192" data-height="144" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="320" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv.360p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="360p.vp9.webm" data-width="480" data-height="360" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/b/b9/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv/AFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="480" data-height="360" /><track src="https://commons.wikimedia.org/w/api.php?action=timedtext&title=File%3AAFSC_Film%2C_NAVSTAR_GPS-Circa_1977.ogv&lang=en&trackformat=vtt&origin=%2A" kind="subtitles" type="text/vtt" srclang="en" label="English ‪(en)‬" data-dir="ltr" /></video><figcaption>Air Force film introducing the Navstar Global Positioning System, circa 1977</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:GPS24goldenSMALL.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/GPS24goldenSMALL.gif/220px-GPS24goldenSMALL.gif" decoding="async" width="220" height="159" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/GPS24goldenSMALL.gif/330px-GPS24goldenSMALL.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/e/e5/GPS24goldenSMALL.gif 2x" data-file-width="414" data-file-height="299" /></a><figcaption>GPS constellation system animation</figcaption></figure> The GPS project was launched in the United States in 1973 to overcome the limitations of previous navigation systems,<a href="#cite_note-13">[13]</a> combining ideas from several predecessors, including classified engineering design studies from the 1960s. The <a href="/wiki/U.S._Department_of_Defense" class="mw-redirect" title="U.S. Department of Defense">U.S. Department of Defense</a> developed the system, which originally used 24 satellites, for use by the United States military, and became fully operational in 1993. Civilian use was allowed from the 1980s. <a href="/wiki/Roger_L._Easton" title="Roger L. Easton">Roger L. Easton</a> of the <a href="/wiki/Naval_Research_Laboratory" class="mw-redirect" title="Naval Research Laboratory">Naval Research Laboratory</a>, <a href="/wiki/Ivan_A._Getting" class="mw-redirect" title="Ivan A. Getting">Ivan A. Getting</a> of <a href="/wiki/The_Aerospace_Corporation" title="The Aerospace Corporation">The Aerospace Corporation</a>, and <a href="/wiki/Bradford_Parkinson" title="Bradford Parkinson">Bradford Parkinson</a> of the <a href="/wiki/Applied_Physics_Laboratory" title="Applied Physics Laboratory">Applied Physics Laboratory</a> are credited with inventing it.<a href="#cite_note-DarrinO'Leary2009-14">[14]</a> The work of <a href="/wiki/Gladys_West" title="Gladys West">Gladys West</a> on the creation of the mathematical geodetic Earth model is credited as instrumental in the development of computational techniques for detecting satellite positions with the precision needed for GPS.<a href="#cite_note-15">[15]</a><a href="#cite_note-16">[16]</a> The design of GPS is based partly on similar ground-based <a href="/wiki/Radio-navigation" class="mw-redirect" title="Radio-navigation">radio-navigation</a> systems, such as <a href="/wiki/LORAN" title="LORAN">LORAN</a> and the <a href="/wiki/Decca_Navigator_System" title="Decca Navigator System">Decca Navigator System</a>, developed in the early 1940s. In 1955, <a href="/wiki/Friedwardt_Winterberg" title="Friedwardt Winterberg">Friedwardt Winterberg</a> proposed a test of <a href="/wiki/General_relativity" title="General relativity">general relativity</a>—detecting time slowing in a strong gravitational field using accurate atomic clocks placed in orbit inside artificial satellites. Special and general relativity predicted that the clocks on GPS satellites, as observed by those on Earth, run 38 microseconds faster per day than those on the Earth. The design of GPS corrects for this difference; because without doing so, GPS calculated positions would accumulate errors of up to 10 kilometers per day (6 mi/d).<a href="#cite_note-17">[17]</a> <div class="mw-heading mw-heading3"><h3 id="Predecessors">Predecessors</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=3" title="Edit section: Predecessors">edit</a>]</div> When the Soviet Union launched its first artificial satellite (<a href="/wiki/Sputnik_1" title="Sputnik 1">Sputnik 1</a>) in 1957, two American physicists, William Guier and George Weiffenbach, at <a href="/wiki/Johns_Hopkins_University" title="Johns Hopkins University">Johns Hopkins University</a>'s <a href="/wiki/Applied_Physics_Laboratory" title="Applied Physics Laboratory">Applied Physics Laboratory</a> (APL) monitored its radio transmissions.<a href="#cite_note-guier-weiffenbach-18">[18]</a> Within hours they realized that, because of the <a href="/wiki/Doppler_effect" title="Doppler effect">Doppler effect</a>, they could pinpoint where the satellite was along its orbit. The Director of the APL gave them access to their <a href="/wiki/UNIVAC_I" title="UNIVAC I">UNIVAC I</a> computer to perform the heavy calculations required. <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Managers_for_the_Timation_program.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Managers_for_the_Timation_program.jpg/220px-Managers_for_the_Timation_program.jpg" decoding="async" width="220" height="169" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Managers_for_the_Timation_program.jpg/330px-Managers_for_the_Timation_program.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/70/Managers_for_the_Timation_program.jpg/440px-Managers_for_the_Timation_program.jpg 2x" data-file-width="2736" data-file-height="2096" /></a><figcaption>The <a href="/wiki/Naval_Research_Laboratory" class="mw-redirect" title="Naval Research Laboratory">Naval Research Laboratory</a>’s managers for the Timation program and, later, the GPS program: <a href="/wiki/Roger_L._Easton" title="Roger L. Easton">Roger L. Easton</a> (left) and <a href="/w/index.php?title=Al_Bartholemew&action=edit&redlink=1" class="new" title="Al Bartholemew (page does not exist)">Al Bartholemew</a>.</figcaption></figure> Early the next year, Frank McClure, the deputy director of the APL, asked Guier and Weiffenbach to investigate the inverse problem: pinpointing the user's location, given the satellite's. (At the time, the Navy was developing the submarine-launched <a href="/wiki/UGM-27_Polaris" title="UGM-27 Polaris">Polaris</a> missile, which required them to know the submarine's location.) This led them and APL to develop the <a href="/wiki/Transit_(satellite)" title="Transit (satellite)">TRANSIT</a> system.<a href="#cite_note-19">[19]</a> In 1959, ARPA (renamed <a href="/wiki/DARPA" title="DARPA">DARPA</a> in 1972) also played a role in TRANSIT.<a href="#cite_note-20">[20]</a><a href="#cite_note-Alexandrow-21">[21]</a><a href="#cite_note-gap-22">[22]</a> TRANSIT was first successfully tested in 1960.<a href="#cite_note-23">[23]</a> It used a <a href="/wiki/Satellite_constellation" title="Satellite constellation">constellation</a> of five satellites and could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the <a href="/wiki/Timation" title="Timation">Timation</a> satellite, which proved the feasibility of placing accurate clocks in space, a technology required for GPS. In the 1970s, the ground-based <a href="/wiki/Omega_(navigation_system)" title="Omega (navigation system)">OMEGA</a> navigation system, based on phase comparison of signal transmission from pairs of stations,<a href="#cite_note-24">[24]</a> became the first worldwide radio navigation system. Limitations of these systems drove the need for a more universal navigation solution with greater accuracy. Although there were wide needs for accurate navigation in military and civilian sectors, almost none of those was seen as justification for the billions of dollars it would cost in research, development, deployment, and operation of a constellation of navigation satellites. During the <a href="/wiki/Cold_War" title="Cold War">Cold War</a> <a href="/wiki/Arms_race" title="Arms race">arms race</a>, the nuclear threat to the existence of the United States was the one need that did justify this cost in the view of the United States Congress. This deterrent effect is why GPS was funded.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] It is also the reason for the ultra-secrecy at that time. The <a href="/wiki/Nuclear_triad" title="Nuclear triad">nuclear triad</a> consisted of the United States Navy's <a href="/wiki/Submarine-launched_ballistic_missile" title="Submarine-launched ballistic missile">submarine-launched ballistic missiles</a> (SLBMs) along with <a href="/wiki/United_States_Air_Force" title="United States Air Force">United States Air Force</a> (USAF) <a href="/wiki/Strategic_bomber" title="Strategic bomber">strategic bombers</a> and <a href="/wiki/Intercontinental_ballistic_missile" title="Intercontinental ballistic missile">intercontinental ballistic missiles</a> (ICBMs). Considered vital to the <a href="/wiki/Nuclear_strategy" title="Nuclear strategy">nuclear deterrence</a> posture, accurate determination of the SLBM launch position was a <a href="/wiki/Force_multiplication" title="Force multiplication">force multiplier</a>. Precise navigation would enable United States <a href="/wiki/Ballistic_missile_submarine" title="Ballistic missile submarine">ballistic missile submarines</a> to get an accurate fix of their positions before they launched their SLBMs.<a href="#cite_note-25">[25]</a> The USAF, with two thirds of the nuclear triad, also had requirements for a more accurate and reliable navigation system. The U.S. Navy and U.S. Air Force were developing their own technologies in parallel to solve what was essentially the same problem. To increase the survivability of ICBMs, there was a proposal to use mobile launch platforms (comparable to the Soviet <a href="/wiki/RT-23_Molodets" title="RT-23 Molodets">SS-24</a> and <a href="/wiki/RT-2PM_Topol" title="RT-2PM Topol">SS-25</a>) and so the need to fix the launch position had similarity to the SLBM situation. In 1960, the Air Force proposed a radio-navigation system called MOSAIC (MObile System for Accurate ICBM Control) that was essentially a 3-D LORAN System. A follow-on study, Project 57, was performed in 1963 and it was "in this study that the GPS concept was born". That same year, the concept was pursued as Project 621B, which had "many of the attributes that you now see in GPS"<a href="#cite_note-26">[26]</a> and promised increased accuracy for U.S. Air Force bombers as well as ICBMs. <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Navigation_Technology_Satellite_%E2%80%93_II.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Navigation_Technology_Satellite_%E2%80%93_II.jpg/220px-Navigation_Technology_Satellite_%E2%80%93_II.jpg" decoding="async" width="220" height="360" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Navigation_Technology_Satellite_%E2%80%93_II.jpg/330px-Navigation_Technology_Satellite_%E2%80%93_II.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Navigation_Technology_Satellite_%E2%80%93_II.jpg/440px-Navigation_Technology_Satellite_%E2%80%93_II.jpg 2x" data-file-width="1620" data-file-height="2649" /></a><figcaption>Navigation Technology Satellite – II (Timation IV): NTS-II, the first satellite completely designed and built by NRL under GPS Joint Program funding. Launched June 23, 1977.</figcaption></figure> Updates from the Navy TRANSIT system were too slow for the high speeds of Air Force operation. The <a href="/wiki/United_States_Naval_Research_Laboratory" title="United States Naval Research Laboratory">Naval Research Laboratory</a> (NRL) continued making advances with their <a href="/wiki/Timation" title="Timation">Timation</a> (Time Navigation) satellites, first launched in 1967, second launched in 1969, with the third in 1974 carrying the first <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clock</a> into orbit and the fourth launched in 1977.<a href="#cite_note-27">[27]</a> Another important predecessor to GPS came from a different branch of the United States military. In 1964, the <a href="/wiki/United_States_Army" title="United States Army">United States Army</a> orbited its first Sequential Collation of Range (<a href="/wiki/SECOR" title="SECOR">SECOR</a>) satellite used for geodetic surveying.<a href="#cite_note-28">[28]</a> The SECOR system included three ground-based transmitters at known locations that would send signals to the satellite transponder in orbit. A fourth ground-based station, at an undetermined position, could then use those signals to fix its location precisely. The last SECOR satellite was launched in 1969.<a href="#cite_note-29">[29]</a> <div class="mw-heading mw-heading3"><h3 id="Development">Development</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=4" title="Edit section: Development">edit</a>]</div> With these parallel developments in the 1960s, it was realized that a superior system could be developed by synthesizing the best technologies from 621B, Transit, Timation, and SECOR in a multi-service program. Satellite orbital position errors, induced by variations in the <a href="/wiki/Gravity_field" class="mw-redirect" title="Gravity field">gravity field</a> and <a href="/wiki/Refraction" title="Refraction">radar refraction</a> among others, had to be resolved. A team led by Harold L. Jury of Pan Am Aerospace Division in Florida from 1970 to 1973, used real-time data assimilation and recursive estimation to do so, reducing systematic and residual errors to a manageable level to permit accurate navigation.<a href="#cite_note-30">[30]</a> During Labor Day weekend in 1973, a meeting of about twelve military officers at the Pentagon discussed the creation of a Defense Navigation Satellite System (DNSS). It was at this meeting that the real synthesis that became GPS was created. Later that year, the DNSS program was named Navstar.<a href="#cite_note-31">[31]</a> Navstar is often erroneously considered an acronym for "NAVigation System using Timing And Ranging" but was never considered as such by the GPS Joint Program Office (TRW may have once advocated for a different navigational system that used that acronym).<a href="#cite_note-32">[32]</a> With the individual satellites being associated with the name Navstar (as with the predecessors Transit and Timation), a more fully encompassing name was used to identify the constellation of Navstar satellites, Navstar-GPS.<a href="#cite_note-33">[33]</a> Ten "<a href="/wiki/GPS_Block_I" class="mw-redirect" title="GPS Block I">Block I</a>" prototype satellites were launched between 1978 and 1985 (an additional unit was destroyed in a launch failure).<a href="#cite_note-ieee2008-34">[34]</a> The effect of the ionosphere on radio transmission was investigated in a geophysics laboratory of <a href="/wiki/Air_Force_Cambridge_Research_Laboratory" class="mw-redirect" title="Air Force Cambridge Research Laboratory">Air Force Cambridge Research Laboratory</a>, renamed to Air Force Geophysical Research Lab (AFGRL) in 1974. AFGRL developed the Klobuchar model for computing <a href="/wiki/Ionosphere" title="Ionosphere">ionospheric</a> corrections to GPS location.<a href="#cite_note-35">[35]</a> Of note is work done by Australian space scientist <a href="/wiki/Elizabeth_Essex-Cohen" title="Elizabeth Essex-Cohen">Elizabeth Essex-Cohen</a> at AFGRL in 1974. She was concerned with the curving of the paths of radio waves (<a href="/wiki/Atmospheric_refraction" title="Atmospheric refraction">atmospheric refraction</a>) traversing the ionosphere from NavSTAR satellites.<a href="#cite_note-36">[36]</a> After <a href="/wiki/Korean_Air_Lines_Flight_007" title="Korean Air Lines Flight 007">Korean Air Lines Flight 007</a>, a <a href="/wiki/Boeing_747" title="Boeing 747">Boeing 747</a> carrying 269 people, was shot down by a Soviet <a href="/wiki/Interceptor_aircraft" title="Interceptor aircraft">interceptor aircraft</a> after straying in <a href="/wiki/Prohibited_airspace" title="Prohibited airspace">prohibited airspace</a> because of navigational errors,<a href="#cite_note-37">[37]</a> in the vicinity of <a href="/wiki/Sakhalin" title="Sakhalin">Sakhalin</a> and <a href="/wiki/Moneron_Island" title="Moneron Island">Moneron Islands</a>, President <a href="/wiki/Ronald_Reagan" title="Ronald Reagan">Ronald Reagan</a> issued a directive making GPS freely available for civilian use, once it was sufficiently developed, as a common good.<a href="#cite_note-KAL007-38">[38]</a> The first Block II satellite was launched on February 14, 1989,<a href="#cite_note-39">[39]</a> and the 24th satellite was launched in 1994. The GPS program cost at this point, not including the cost of the user equipment but including the costs of the satellite launches, has been estimated at US$5 billion (equivalent to $10 billion in 2023).<a href="#cite_note-40">[40]</a> Initially, the highest-quality signal was reserved for military use, and the signal available for civilian use was intentionally degraded, in a policy known as <a href="/wiki/Selective_Availability" class="mw-redirect" title="Selective Availability">Selective Availability</a>. This changed on May 1, 2000, with U.S. President <a href="/wiki/Bill_Clinton" title="Bill Clinton">Bill Clinton</a> signing a policy directive to turn off Selective Availability to provide the same accuracy to civilians that was afforded to the military. The directive was proposed by the U.S. Secretary of Defense, <a href="/wiki/William_J._Perry" title="William J. Perry">William Perry</a>, in view of the widespread growth of <a href="/wiki/Differential_GPS" title="Differential GPS">differential GPS</a> services by private industry to improve civilian accuracy. Moreover, the U.S. military was developing technologies to deny GPS service to potential adversaries on a regional basis.<a href="#cite_note-41">[41]</a> Selective Availability was removed from the GPS architecture beginning with GPS-III. Since its deployment, the U.S. has implemented several improvements to the GPS service, including new signals for civil use and increased accuracy and integrity for all users, all the while maintaining compatibility with existing GPS equipment. Modernization of the satellite system has been an ongoing initiative by the U.S. Department of Defense through a series of <a href="/wiki/GPS_Block_IIIA" class="mw-redirect" title="GPS Block IIIA">satellite acquisitions</a> to meet the growing needs of the military, civilians, and the commercial market. As of early 2015, high-quality Standard Positioning Service (SPS) GPS receivers provided horizontal accuracy of better than 3.5 meters (11 ft),<a href="#cite_note-gpsgovaccurary-7">[7]</a> although many factors such as receiver and antenna quality and atmospheric issues can affect this accuracy. GPS is owned and operated by the United States government as a national resource. The Department of Defense is the steward of GPS. The Interagency GPS Executive Board (IGEB) oversaw GPS policy matters from 1996 to 2004. After that, the National Space-Based Positioning, Navigation and Timing Executive Committee was established by presidential directive in 2004 to advise and coordinate federal departments and agencies on matters concerning the GPS and related systems.<a href="#cite_note-42">[42]</a> The executive committee is chaired jointly by the Deputy Secretaries of Defense and Transportation. Its membership includes equivalent-level officials from the Departments of State, Commerce, and Homeland Security, the <a href="/wiki/Joint_Chiefs_of_Staff" title="Joint Chiefs of Staff">Joint Chiefs of Staff</a> and <a href="/wiki/NASA" title="NASA">NASA</a>. Components of the executive office of the president participate as observers to the executive committee, and the FCC chairman participates as a liaison. The U.S. Department of Defense is required by law to "maintain a Standard Positioning Service (as defined in the federal radio navigation plan and the standard positioning service signal specification) that will be available on a continuous, worldwide basis" and "develop measures to prevent hostile use of GPS and its augmentations without unduly disrupting or degrading civilian uses". <div class="mw-heading mw-heading3"><h3 id="Timeline_and_modernization">Timeline and modernization</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=5" title="Edit section: Timeline and modernization">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-Prose plainlinks metadata ambox ambox-style ambox-Prose" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/40px-Edit-clear.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/60px-Edit-clear.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/f/f2/Edit-clear.svg/80px-Edit-clear.svg.png 2x" data-file-width="48" data-file-height="48" /></div></td><td class="mbox-text"><div class="mbox-text-span">This section is in <a href="/wiki/MOS:LIST" class="mw-redirect" title="MOS:LIST">list</a> format but may read better as <a href="/wiki/MOS:PROSE" class="mw-redirect" title="MOS:PROSE">prose</a>. You can help by <a class="external text" href="https://en.wikipedia.org/w/index.php?title=Global_Positioning_System&action=edit">converting this section</a>, if appropriate. <a href="/wiki/Help:Editing" title="Help:Editing">Editing help</a> is available. (July 2023)</div></td></tr></tbody></table> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:GPS-0012_San_Diego_Air_%26_Space_Museum.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/GPS-0012_San_Diego_Air_%26_Space_Museum.jpg/220px-GPS-0012_San_Diego_Air_%26_Space_Museum.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/GPS-0012_San_Diego_Air_%26_Space_Museum.jpg/330px-GPS-0012_San_Diego_Air_%26_Space_Museum.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e1/GPS-0012_San_Diego_Air_%26_Space_Museum.jpg/440px-GPS-0012_San_Diego_Air_%26_Space_Museum.jpg 2x" data-file-width="4032" data-file-height="3024" /></a><figcaption><a href="/wiki/Test_article_(aerospace)" title="Test article (aerospace)">Qualification vehicle</a> for GPS Block II on display in <a href="/wiki/San_Diego_Air_%26_Space_Museum" title="San Diego Air & Space Museum">San Diego</a> – the only vehicle on public display.<a href="#cite_note-43">[43]</a></figcaption></figure> <table class="wikitable"> <caption>Summary of satellites<a href="#cite_note-44">[44]</a><a href="#cite_note-45">[45]</a><a href="#cite_note-46">[46]</a> </caption> <tbody><tr> <th rowspan="2">Block</th> <th rowspan="2">Launch period</th> <th colspan="4">Satellite launches</th> <th rowspan="2">Currently in orbit and healthy </th></tr> <tr> <th>Success</th> <th>Failure</th> <th>In preparation</th> <th>Planned </th></tr> <tr> <th><a href="/wiki/GPS_Block_I" class="mw-redirect" title="GPS Block I">I</a> </th> <td>1978–1985</td> <td>10</td> <td>1</td> <td>0</td> <td>0</td> <td>0 </td></tr> <tr> <th><a href="/wiki/GPS_Block_II" class="mw-redirect" title="GPS Block II">II</a> </th> <td>1989–1990</td> <td>9</td> <td>0</td> <td>0</td> <td>0</td> <td>0 </td></tr> <tr> <th><a href="/wiki/GPS_Block_IIA" class="mw-redirect" title="GPS Block IIA">IIA</a> </th> <td>1990–1997</td> <td>19</td> <td>0</td> <td>0</td> <td>0</td> <td>0 </td></tr> <tr> <th><a href="/wiki/GPS_Block_IIR" class="mw-redirect" title="GPS Block IIR">IIR</a> </th> <td>1997–2004</td> <td>12</td> <td>1</td> <td>0</td> <td>0</td> <td>7 </td></tr> <tr> <th><a href="/wiki/GPS_Block_IIR-M" class="mw-redirect" title="GPS Block IIR-M">IIR-M</a> </th> <td>2005–2009</td> <td>8</td> <td>0</td> <td>0</td> <td>0</td> <td>7 </td></tr> <tr> <th><a href="/wiki/GPS_Block_IIF" title="GPS Block IIF">IIF</a> </th> <td>2010–2016</td> <td>12</td> <td>0</td> <td>0</td> <td>0</td> <td>11 </td></tr> <tr> <th><a href="/wiki/GPS_Block_IIIA" class="mw-redirect" title="GPS Block IIIA">IIIA</a> </th> <td>2018–</td> <td>6</td> <td>0</td> <td>4</td> <td>0</td> <td>6 </td></tr> <tr> <th><a href="/wiki/GPS_Block_IIIF" title="GPS Block IIIF">IIIF</a> </th> <td>—</td> <td>0</td> <td>0</td> <td>0</td> <td>22</td> <td>0 </td></tr> <tr> <th colspan="2">Total </th> <td>76</td> <td>2</td> <td>4</td> <td>22</td> <td>31 </td></tr> <tr> <td colspan="7" style="font-size: smaller;">(Last update: September 26, 2024) <a href="/wiki/USA-203" title="USA-203">USA-203</a> from Block IIR-M is unhealthy <a href="#cite_note-47">[47]</a> For a more complete list, see <a href="/wiki/List_of_GPS_satellites" title="List of GPS satellites">List of GPS satellites</a> </td></tr></tbody></table> <ul><li>In 1972, the U.S. Air Force Central Inertial Guidance Test Facility (Holloman Air Force Base) conducted developmental flight tests of four prototype GPS receivers in a Y configuration over <a href="/wiki/White_Sands_Missile_Range" title="White Sands Missile Range">White Sands Missile Range</a>, using ground-based pseudo-satellites.<a href="#cite_note-48">[48]</a></li> <li>In 1978, the first experimental Block-I GPS satellite was launched.<a href="#cite_note-ieee2008-34">[34]</a></li> <li>In 1983, after Soviet Union interceptor aircraft shot down the civilian airliner <a href="/wiki/Korean_Air_Flight_007" class="mw-redirect" title="Korean Air Flight 007">KAL 007</a> that strayed into <a href="/wiki/Prohibited_airspace" title="Prohibited airspace">prohibited airspace</a> because of navigational errors, killing all 269 people on board, U.S. President <a href="/wiki/Ronald_Reagan" title="Ronald Reagan">Ronald Reagan</a> announced that GPS would be made available for civilian uses once it was completed,<a href="#cite_note-49">[49]</a><a href="#cite_note-50">[50]</a> although it had been publicly known as early as 1979, that the CA code (Coarse/Acquisition code) would be available to civilian users.<a href="#cite_note-breeze-19790916-91-51">[51]</a><a href="#cite_note-breeze-19790916-97-52">[52]</a></li> <li>By 1985, ten more experimental Block-I satellites had been launched to validate the concept.</li> <li>Beginning in 1988, command and control of these satellites was moved from <a href="/wiki/Onizuka_AFS" class="mw-redirect" title="Onizuka AFS">Onizuka AFS</a>, California to the <a href="/wiki/2nd_Space_Operations_Squadron" class="mw-redirect" title="2nd Space Operations Squadron">2nd Satellite Control Squadron</a> (2SCS) located at <a href="/wiki/Schriever_Space_Force_Base" title="Schriever Space Force Base">Schriever Space Force Base</a> in <a href="/wiki/Colorado_Springs,_Colorado" title="Colorado Springs, Colorado">Colorado Springs, Colorado</a>.<a href="#cite_note-53">[53]</a><a href="#cite_note-54">[54]</a></li> <li>On February 14, 1989, the first modern Block-II satellite was launched.</li> <li>The <a href="/wiki/Gulf_War" title="Gulf War">Gulf War</a> from 1990 to 1991 was the first conflict in which the military widely used GPS.<a href="#cite_note-55">[55]</a></li> <li>In 1991, DARPA's project to create a miniature GPS receiver successfully ended, replacing the previous 16 kg (35 lb) military receivers with a 1.25 kg (2.8 lb) all-digital handheld GPS receiver.<a href="#cite_note-Alexandrow-21">[21]</a></li> <li>In 1991, <a href="/wiki/TomTom" title="TomTom">TomTom</a>, a Dutch sat-nav manufacturer was founded.</li> <li>In 1992, the <a href="/wiki/2nd_Space_Wing" class="mw-redirect" title="2nd Space Wing">2nd Space Wing</a>, which originally managed the system, was inactivated and replaced by the <a href="/wiki/50th_Space_Wing" title="50th Space Wing">50th Space Wing</a>.</li> <li>By December 1993, GPS achieved <a href="/wiki/Initial_operational_capability" class="mw-redirect" title="Initial operational capability">initial operational capability</a> (IOC), with a full constellation (24 satellites) available and providing the Standard Positioning Service (SPS).<a href="#cite_note-IOCFOC-56">[56]</a></li> <li>Full Operational Capability (FOC) was declared by <a href="/wiki/Air_Force_Space_Command" class="mw-redirect" title="Air Force Space Command">Air Force Space Command</a> (AFSPC) in April 1995, signifying full availability of the military's secure Precise Positioning Service (PPS).<a href="#cite_note-IOCFOC-56">[56]</a></li> <li>In 1996, recognizing the importance of GPS to civilian users as well as military users, U.S. President <a href="/wiki/Bill_Clinton" title="Bill Clinton">Bill Clinton</a> issued a policy directive<a href="#cite_note-57">[57]</a> declaring GPS a <a href="/wiki/Dual-use" class="mw-redirect" title="Dual-use">dual-use</a> system and establishing an <a href="/wiki/Interagency_GPS_Executive_Board" title="Interagency GPS Executive Board">Interagency GPS Executive Board</a> to manage it as a national asset.</li> <li>In 1998, United States Vice President <a href="/wiki/Al_Gore" title="Al Gore">Al Gore</a> announced plans to upgrade GPS with two new civilian signals for enhanced user accuracy and reliability, particularly with respect to aviation safety, and in 2000 the <a href="/wiki/United_States_Congress" title="United States Congress">United States Congress</a> authorized the effort, referring to it as <a href="/wiki/GPS_III" class="mw-redirect" title="GPS III">GPS III</a>.</li> <li>On May 2, 2000 "Selective Availability" was discontinued as a result of the 1996 executive order, allowing civilian users to receive a non-degraded signal globally.</li> <li>In 2004, the United States government signed an agreement with the European Community establishing cooperation related to GPS and Europe's <a href="/wiki/Galileo_(satellite_navigation)" title="Galileo (satellite navigation)">Galileo system</a>.</li> <li>In 2004, United States President <a href="/wiki/George_W._Bush" title="George W. Bush">George W. Bush</a> updated the national policy and replaced the executive board with the National Executive Committee for Space-Based Positioning, Navigation, and Timing.<a href="#cite_note-58">[58]</a></li> <li>In November 2004, <a href="/wiki/Qualcomm" title="Qualcomm">Qualcomm</a> announced successful tests of <a href="/wiki/Assisted_GPS" class="mw-redirect" title="Assisted GPS">assisted GPS</a> for <a href="/wiki/Mobile_phones" class="mw-redirect" title="Mobile phones">mobile phones</a>.<a href="#cite_note-59">[59]</a></li> <li>In 2005, the first modernized GPS satellite was launched and began transmitting a second civilian signal (L2C) for enhanced user performance.<a href="#cite_note-60">[60]</a></li> <li>On September 14, 2007, the aging mainframe-based <a href="/wiki/Ground_segment" title="Ground segment">Ground Segment</a> Control System was transferred to the new Architecture Evolution Plan.<a href="#cite_note-61">[61]</a></li> <li>On May 19, 2009, the United States <a href="/wiki/Government_Accountability_Office" title="Government Accountability Office">Government Accountability Office</a> issued a report warning that some GPS satellites could fail as soon as 2010.<a href="#cite_note-62">[62]</a></li> <li>On May 21, 2009, the <a href="/wiki/Air_Force_Space_Command" class="mw-redirect" title="Air Force Space Command">Air Force Space Command</a> allayed fears of GPS failure, saying: "There's only a small risk we will not continue to exceed our performance standard."<a href="#cite_note-63">[63]</a></li> <li>On January 11, 2010, an update of ground control systems caused a software incompatibility with 8,000 to 10,000 military receivers manufactured by a division of Trimble Navigation Limited of Sunnyvale, California.[<a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify">clarification needed</a>]<a href="#cite_note-64">[64]</a></li> <li>On February 25, 2010,<a href="#cite_note-65">[65]</a> the U.S. Air Force awarded the contract to <a href="/wiki/Raytheon_Company" class="mw-redirect" title="Raytheon Company">Raytheon Company</a> to develop the GPS Next Generation Operational Control System (OCX) to improve accuracy and availability of GPS navigation signals, and serve as a critical part of GPS modernization.</li> <li>July 24, 2020, operation of the GPS constellation is transferred to the newly established <a href="/wiki/United_States_Space_Force" title="United States Space Force">U.S. Space Force</a> as part of its establishment.<a href="#cite_note-2nd_Space_Operations_Squadron-66">[66]</a><figure typeof="mw:File/Thumb"><a href="/wiki/File:2nd_Space_Operations_Squadron_emblem.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b3/2nd_Space_Operations_Squadron_emblem.png/199px-2nd_Space_Operations_Squadron_emblem.png" decoding="async" width="199" height="266" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b3/2nd_Space_Operations_Squadron_emblem.png/299px-2nd_Space_Operations_Squadron_emblem.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b3/2nd_Space_Operations_Squadron_emblem.png/399px-2nd_Space_Operations_Squadron_emblem.png 2x" data-file-width="433" data-file-height="577" /></a><figcaption>Emblem of the <a href="/wiki/2nd_Space_Operations_Squadron" class="mw-redirect" title="2nd Space Operations Squadron">2nd Space Operations Squadron</a> – the unit responsible for operating the constellation </figcaption></figure></li> <li>On 13 October 2023, the Space Force activated <a href="/wiki/Positioning,_Navigation,_and_Timing_Integrated_Mission_Delta_(Provisional)" class="mw-redirect" title="Positioning, Navigation, and Timing Integrated Mission Delta (Provisional)">PNT Delta (Provisional)</a> to manage US <a href="/wiki/Satellite_navigation" title="Satellite navigation">navigation warfare</a> assets. <a href="/wiki/2nd_Space_Operations_Squadron" class="mw-redirect" title="2nd Space Operations Squadron">2SOPS</a> and GPS operations were realigned under this new <a href="/wiki/Structure_of_the_United_States_Space_Force" title="Structure of the United States Space Force">Delta</a>.<a href="#cite_note-2nd_Space_Operations_Squadron-66">[66]</a></li></ul> <div class="mw-heading mw-heading3"><h3 id="Awards">Awards</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=6" title="Edit section: Awards">edit</a>]</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:181206-F-DT527-136.jpg" class="mw-file-description"><img alt="Air Force Space Commander presents Gladys West with an award as she is inducted into the Air Force Space and Missile Pioneers Hall of Fame for her GPS work on December 6, 2018." src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5a/181206-F-DT527-136.jpg/220px-181206-F-DT527-136.jpg" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5a/181206-F-DT527-136.jpg/330px-181206-F-DT527-136.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5a/181206-F-DT527-136.jpg/440px-181206-F-DT527-136.jpg 2x" data-file-width="5568" data-file-height="3712" /></a><figcaption>AFSPC Vice Commander Lt. Gen. D. T. Thompson presents Gladys West with an award as she is inducted into the Air Force Space and Missile Pioneers Hall of Fame.</figcaption></figure> On February 10, 1993, the <a href="/wiki/National_Aeronautic_Association" title="National Aeronautic Association">National Aeronautic Association</a> selected the GPS Team as winners of the 1992 <a href="/wiki/Collier_Trophy" title="Collier Trophy">Robert J. Collier Trophy</a>, the US's most prestigious aviation award. This team combines researchers from the Naval Research Laboratory, the U.S. Air Force, the <a href="/wiki/Aerospace_Corporation" class="mw-redirect" title="Aerospace Corporation">Aerospace Corporation</a>, <a href="/wiki/Rockwell_International" title="Rockwell International">Rockwell International</a> Corporation, and <a href="/wiki/IBM" title="IBM">IBM</a> Federal Systems Company. The citation honors them "for the most significant development for safe and efficient navigation and surveillance of air and spacecraft since the introduction of radio navigation 50 years ago". Two GPS developers received the <a href="/wiki/United_States_National_Academy_of_Engineering" class="mw-redirect" title="United States National Academy of Engineering">National Academy of Engineering</a> <a href="/wiki/Charles_Stark_Draper_Prize" title="Charles Stark Draper Prize">Charles Stark Draper Prize</a> for 2003: <ul><li><a href="/wiki/Ivan_Getting" title="Ivan Getting">Ivan Getting</a>, emeritus president of <a href="/wiki/The_Aerospace_Corporation" title="The Aerospace Corporation">The Aerospace Corporation</a> and an engineer at <a href="/wiki/Massachusetts_Institute_of_Technology" title="Massachusetts Institute of Technology">Massachusetts Institute of Technology</a>, established the basis for GPS, improving on the <a href="/wiki/World_War_II" title="World War II">World War II</a> land-based radio system called LORAN (Long-range Radio Aid to Navigation).</li> <li><a href="/wiki/Bradford_Parkinson" title="Bradford Parkinson">Bradford Parkinson</a>, professor of <a href="/wiki/Aeronautics" title="Aeronautics">aeronautics</a> and <a href="/wiki/Astronautics" title="Astronautics">astronautics</a> at <a href="/wiki/Stanford_University" title="Stanford University">Stanford University</a>, conceived the present satellite-based system in the early 1960s and developed it in conjunction with the U.S. Air Force. Parkinson served twenty-one years in the Air Force, from 1957 to 1978, and retired with the rank of colonel.</li></ul> GPS developer <a href="/wiki/Roger_L._Easton" title="Roger L. Easton">Roger L. Easton</a> received the <a href="/wiki/National_Medal_of_Technology" class="mw-redirect" title="National Medal of Technology">National Medal of Technology</a> on February 13, 2006.<a href="#cite_note-67">[67]</a> <a href="/wiki/Francis_X._Kane" title="Francis X. Kane">Francis X. Kane</a> (Col. USAF, ret.) was inducted into the U.S. Air Force Space and Missile Pioneers Hall of Fame at Lackland A.F.B., San Antonio, Texas, March 2, 2010, for his role in space technology development and the engineering design concept of GPS conducted as part of Project 621B. In 1998, GPS technology was inducted into the <a href="/wiki/Space_Foundation" title="Space Foundation">Space Foundation</a> <a href="/wiki/Space_Technology_Hall_of_Fame" class="mw-redirect" title="Space Technology Hall of Fame">Space Technology Hall of Fame</a>.<a href="#cite_note-68">[68]</a> On October 4, 2011, the <a href="/wiki/International_Astronautical_Federation" title="International Astronautical Federation">International Astronautical Federation</a> (IAF) awarded the Global Positioning System (GPS) its 60th Anniversary Award, nominated by IAF member, the American Institute for Aeronautics and Astronautics (AIAA). The IAF Honors and Awards Committee recognized the uniqueness of the GPS program and the exemplary role it has played in building international collaboration for the benefit of humanity.<a href="#cite_note-69">[69]</a> On December 6, 2018, Gladys West was inducted into the Air Force Space and Missile Pioneers Hall of Fame in recognition of her work on an extremely accurate geodetic Earth model, which was ultimately used to determine the orbit of the GPS constellation.<a href="#cite_note-70">[70]</a> On February 12, 2019, four founding members of the project were awarded the Queen Elizabeth Prize for Engineering with the chair of the awarding board stating: "Engineering is the foundation of civilisation; ...They've re-written, in a major way, the infrastructure of our world."<a href="#cite_note-71">[71]</a> <div class="mw-heading mw-heading2"><h2 id="Principles">Principles</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=7" title="Edit section: Principles">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></div></td><td class="mbox-text"><div class="mbox-text-span">This section needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a>. Please help <a href="/wiki/Special:EditPage/Global_Positioning_System" title="Special:EditPage/Global Positioning System">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed. (March 2015) (<a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a>)</div></td></tr></tbody></table> The GPS satellites carry very stable <a href="/wiki/Atomic_clocks" class="mw-redirect" title="Atomic clocks">atomic clocks</a> that are synchronized with one another and with the reference atomic clocks at the ground control stations; any drift of the clocks aboard the satellites from the reference time maintained on the ground stations is corrected regularly.<a href="#cite_note-72">[72]</a> Since the speed of <a href="/wiki/Radio_wave" title="Radio wave">radio waves</a> (<a href="/wiki/Speed_of_light" title="Speed of light">speed of light</a>)<a href="#cite_note-73">[73]</a> is constant and independent of the satellite speed, the time delay between when the satellite transmits a signal and the ground station receives it is proportional to the distance from the satellite to the ground station. With the distance information collected from multiple ground stations, the location coordinates of any satellite at any time can be calculated with great precision. Each GPS satellite carries an accurate record of its own position and time, and broadcasts that data continuously. Based on data received from multiple GPS <a href="/wiki/Satellite" title="Satellite">satellites</a>, an end user's GPS receiver can calculate its own <a href="/wiki/Four-dimensional_space" title="Four-dimensional space">four-dimensional position</a> in <a href="/wiki/Spacetime" title="Spacetime">spacetime</a>; However, at a minimum, four satellites must be in view of the receiver for it to compute four unknown quantities (three position coordinates and the deviation of its own clock from satellite time).<a href="#cite_note-74">[74]</a> <div class="mw-heading mw-heading3"><h3 id="More_detailed_description">More detailed description</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=8" title="Edit section: More detailed description">edit</a>]</div> Each GPS satellite continually broadcasts a signal (<a href="/wiki/Carrier_wave" title="Carrier wave">carrier wave</a> with <a href="/wiki/Modulation" title="Modulation">modulation</a>) that includes: <ul><li>A <a href="/wiki/Pseudorandom_binary_sequence" title="Pseudorandom binary sequence">pseudorandom</a> code (sequence of ones and zeros) that is known to the receiver. By time-aligning a receiver-generated version and the receiver-measured version of the code, the time of arrival (TOA) of a defined point in the code sequence, called an epoch, can be found in the receiver clock time scale</li> <li>A message that includes the time of transmission (TOT) of the code epoch (in GPS time scale) and the satellite position at that time</li></ul> Conceptually, the receiver measures the TOAs (according to its own clock) of four satellite signals. From the TOAs and the TOTs, the receiver forms four <a href="/wiki/Time_of_flight" title="Time of flight">time of flight</a> (TOF) values, which are (given the speed of light) approximately equivalent to receiver-satellite ranges plus time difference between the receiver and GPS satellites multiplied by speed of light, which are called pseudo-ranges. The receiver then computes its three-dimensional position and clock deviation from the four TOFs. In practice the receiver position (in three dimensional <a href="/wiki/Cartesian_coordinate_system" title="Cartesian coordinate system">Cartesian coordinates</a> with origin at the Earth's center) and the offset of the receiver clock relative to the GPS time are computed simultaneously, using the <a href="#Navigation_equations">navigation equations</a> to process the TOFs. The receiver's Earth-centered solution location is usually converted to <a href="/wiki/Latitude" title="Latitude">latitude</a>, <a href="/wiki/Longitude" title="Longitude">longitude</a> and height relative to an ellipsoidal Earth model. The height may then be further converted to height relative to the <a href="/wiki/Geoid" title="Geoid">geoid</a>, which is essentially mean sea level. These coordinates may be displayed, such as on a <a href="/wiki/Moving_map_display" title="Moving map display">moving map display</a>, or recorded or used by some other system, such as a vehicle guidance system. <div class="mw-heading mw-heading3"><h3 id="User-satellite_geometry">User-satellite geometry</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=9" title="Edit section: User-satellite geometry">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="#Geometric_interpretation">§ Geometric interpretation</a></div> Although usually not formed explicitly in the receiver processing, the conceptual time differences of arrival (TDOAs) define the measurement geometry. Each TDOA corresponds to a <a href="/wiki/Hyperboloid" title="Hyperboloid">hyperboloid</a> of revolution (see <a href="/wiki/Multilateration" class="mw-redirect" title="Multilateration">Multilateration</a>). The line connecting the two satellites involved (and its extensions) forms the axis of the hyperboloid. The receiver is located at the point where three hyperboloids intersect.<a href="#cite_note-Abel1-75">[75]</a><a href="#cite_note-Fang-76">[76]</a> It is sometimes incorrectly said that the user location is at the intersection of three spheres. While simpler to visualize, this is the case only if the receiver has a clock synchronized with the satellite clocks (i.e., the receiver measures true ranges to the satellites rather than range differences). There are marked performance benefits to the user carrying a clock synchronized with the satellites. Foremost is that only three satellites are needed to compute a position solution. If it were an essential part of the GPS concept that all users needed to carry a synchronized clock, a smaller number of satellites could be deployed, but the cost and complexity of the user equipment would increase. <div class="mw-heading mw-heading3"><h3 id="Receiver_in_continuous_operation">Receiver in continuous operation</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=10" title="Edit section: Receiver in continuous operation">edit</a>]</div> The description above is representative of a receiver start-up situation. Most receivers have a <a href="/wiki/Track_algorithm" title="Track algorithm">track algorithm</a>, sometimes called a tracker, that combines sets of satellite measurements collected at different times—in effect, taking advantage of the fact that successive receiver positions are usually close to each other. After a set of measurements are processed, the tracker predicts the receiver location corresponding to the next set of satellite measurements. When the new measurements are collected, the receiver uses a weighting scheme to combine the new measurements with the tracker prediction. In general, a tracker can (a) improve receiver position and time accuracy, (b) reject bad measurements, and (c) estimate receiver speed and direction. The disadvantage of a tracker is that changes in speed or direction can be computed only with a delay, and that derived direction becomes inaccurate when the distance traveled between two position measurements drops below or near the <a href="/wiki/Random_error" class="mw-redirect" title="Random error">random error</a> of position measurement. GPS units can use measurements of the <a href="/wiki/Doppler_shift" class="mw-redirect" title="Doppler shift">Doppler shift</a> of the signals received to compute velocity accurately.<a href="#cite_note-77">[77]</a> More advanced navigation systems use additional sensors like a <a href="/wiki/Compass" title="Compass">compass</a> or an <a href="/wiki/Inertial_navigation_system" title="Inertial navigation system">inertial navigation system</a> to complement GPS. <div class="mw-heading mw-heading3"><h3 id="Non-navigation_applications">Non-navigation applications</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=11" title="Edit section: Non-navigation applications">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">For a list of applications, see <a href="#Applications">§ Applications</a>.</div> GPS requires four or more satellites to be visible for accurate navigation. The solution of the <a href="#Navigation_equations">navigation equations</a> gives the position of the receiver along with the difference between the time kept by the receiver's on-board clock and the true time-of-day, thereby eliminating the need for a more precise and possibly impractical receiver based clock. Applications for GPS such as <a href="/wiki/Time_transfer" class="mw-redirect" title="Time transfer">time transfer</a>, traffic signal timing, and <a href="/wiki/IS-95#Physical_layer" class="mw-redirect" title="IS-95">synchronization of cell phone base stations</a>, <a href="#Timekeeping">make use of</a> this cheap and highly accurate timing. Some GPS applications use this time for display, or, other than for the basic position calculations, do not use it at all. Although four satellites are required for normal operation, fewer apply in special cases. If one variable is already known, a receiver can determine its position using only three satellites. For example, a ship on the open ocean usually has a known elevation <a href="/wiki/Tidal_range" title="Tidal range">close to 0m</a>, and the elevation of an aircraft may be known.<a href="#cite_note-78">[a]</a> Some GPS receivers may use additional clues or assumptions such as reusing the last known altitude, <a href="/wiki/Dead_reckoning" title="Dead reckoning">dead reckoning</a>, <a href="/wiki/Inertial_navigation_system" title="Inertial navigation system">inertial navigation</a>, or including information from the vehicle computer, to give a (possibly degraded) position when fewer than four satellites are visible.<a href="#cite_note-79">[78]</a><a href="#cite_note-NAVGPS-80">[79]</a><a href="#cite_note-81">[80]</a> <div class="mw-heading mw-heading2"><h2 id="Structure">Structure</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=12" title="Edit section: Structure">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></div></td><td class="mbox-text"><div class="mbox-text-span">This section needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a>. Please help <a href="/wiki/Special:EditPage/Global_Positioning_System" title="Special:EditPage/Global Positioning System">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed. (March 2015) (<a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a>)</div></td></tr></tbody></table> The current GPS consists of three major segments. These are the space segment, a control segment, and a user segment.<a href="#cite_note-breeze-19790916-97-52">[52]</a> The <a href="/wiki/U.S._Space_Force" class="mw-redirect" title="U.S. Space Force">U.S. Space Force</a> develops, maintains, and operates the space and control segments. GPS satellites <a href="/wiki/Broadcast_signal" class="mw-redirect" title="Broadcast signal">broadcast signals</a> from space, and each GPS receiver uses these signals to calculate its three-dimensional location (latitude, longitude, and altitude) and the current time.<a href="#cite_note-gps.gov-82">[81]</a> <div class="mw-heading mw-heading3"><h3 id="Space_segment">Space segment</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=13" title="Edit section: Space segment">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/GPS_satellite_blocks" title="GPS satellite blocks">GPS satellite blocks</a> and <a href="/wiki/List_of_GPS_satellites" title="List of GPS satellites">List of GPS satellites</a></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:160921-F-0000U-001.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/160921-F-0000U-001.jpg/220px-160921-F-0000U-001.jpg" decoding="async" width="220" height="148" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/160921-F-0000U-001.jpg/330px-160921-F-0000U-001.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1c/160921-F-0000U-001.jpg/440px-160921-F-0000U-001.jpg 2x" data-file-width="2850" data-file-height="1920" /></a><figcaption>GPS II underwent a four-month series of qualification tests in the AEDC Mark I Space Chamber to determine whether the satellite could withstand extreme heat and cold in space, 1985.</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:GPS24goldenSML.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/2/27/GPS24goldenSML.gif" decoding="async" width="297" height="324" class="mw-file-element" data-file-width="297" data-file-height="324" /></a><figcaption>A visual example of a 24-satellite GPS constellation in motion with the Earth rotating. Notice how the number of satellites in view from a given point on the Earth's surface changes with time. The point in this example is in Golden, Colorado, USA (<style data-mw-deduplicate="TemplateStyles:r1156832818">.mw-parser-output .geo-default,.mw-parser-output .geo-dms,.mw-parser-output .geo-dec{display:inline}.mw-parser-output .geo-nondefault,.mw-parser-output .geo-multi-punct,.mw-parser-output .geo-inline-hidden{display:none}.mw-parser-output .longitude,.mw-parser-output .latitude{white-space:nowrap}</style><a class="external text" href="https://geohack.toolforge.org/geohack.php?pagename=Global_Positioning_System&params=39.7469_N_105.2108_W_">39°44′49″N 105°12′39″W / 39.7469°N 105.2108°W / 39.7469; -105.2108</a>).</figcaption></figure> The space segment (SS) is composed of 24 to 32 satellites, or Space Vehicles (SV), in <a href="/wiki/Medium_Earth_orbit" title="Medium Earth orbit">medium Earth orbit</a>, and also includes the payload adapters to the boosters required to launch them into orbit. The GPS design originally called for 24 SVs, eight each in three approximately circular <a href="/wiki/Orbital_plane_(astronomy)" class="mw-redirect" title="Orbital plane (astronomy)">orbits</a>,<a href="#cite_note-83">[82]</a> but this was modified to six orbital planes with four satellites each.<a href="#cite_note-84">[83]</a> The six orbit planes have approximately 55° <a href="/wiki/Inclination" class="mw-redirect" title="Inclination">inclination</a> (tilt relative to the Earth's <a href="/wiki/Equator" title="Equator">equator</a>) and are separated by 60° <a href="/wiki/Right_ascension" title="Right ascension">right ascension</a> of the <a href="/wiki/Orbital_node" title="Orbital node">ascending node</a> (angle along the equator from a reference point to the orbit's intersection).<a href="#cite_note-GPS_overview_from_JPO-85">[84]</a> The <a href="/wiki/Orbital_period" title="Orbital period">orbital period</a> is one-half of a <a href="/wiki/Sidereal_day" class="mw-redirect" title="Sidereal day">sidereal day</a>, i.e., 11 hours and 58 minutes, so that <a href="/wiki/Satellite_revisit_period" title="Satellite revisit period">the satellites pass over the same locations</a><a href="#cite_note-86">[85]</a> or almost the same locations<a href="#cite_note-The_GPS_Satellite_Constellation-87">[86]</a> every day. The orbits are arranged so that at least six satellites are always within <a href="/wiki/Line-of-sight_propagation" title="Line-of-sight propagation">line of sight</a> from everywhere on the Earth's surface (see animation at right).<a href="#cite_note-88">[87]</a> The result of this objective is that the four satellites are not evenly spaced (90°) apart within each orbit. In general terms, the angular difference between satellites in each orbit is 30°, 105°, 120°, and 105° apart, which sum to 360°.<a href="#cite_note-avionicswest-89">[88]</a> Orbiting at an altitude of approximately 20,200 km (12,600 mi); orbital radius of approximately 26,600 km (16,500 mi),<a href="#cite_note-90">[89]</a> each SV makes two complete orbits each <a href="/wiki/Sidereal_day" class="mw-redirect" title="Sidereal day">sidereal day</a>, repeating the same <a href="/wiki/Ground_track" class="mw-redirect" title="Ground track">ground track</a> each day.<a href="#cite_note-91">[90]</a> This was very helpful during development because even with only four satellites, correct alignment means all four are visible from one spot for a few hours each day. For military operations, the ground track repeat can be used to ensure good coverage in combat zones. As of February 2019<a class="external text" href="https://en.wikipedia.org/w/index.php?title=Global_Positioning_System&action=edit">[update]</a>,<a href="#cite_note-92">[91]</a> there are 31 satellites in the GPS <a href="/wiki/Satellite_constellation" title="Satellite constellation">constellation</a>, 27 of which are in use at a given time with the rest allocated as stand-bys. A 32nd was launched in 2018, but as of July 2019 is still in evaluation. More decommissioned satellites are in orbit and available as spares. The additional satellites improve the precision of GPS receiver calculations by providing redundant measurements. With the increased number of satellites, the constellation was changed to a nonuniform arrangement. Such an arrangement was shown to improve accuracy but also improves reliability and availability of the system, relative to a uniform system, when multiple satellites fail.<a href="#cite_note-93">[92]</a> With the expanded constellation, nine satellites are usually visible at any time from any point on the Earth with a clear horizon, ensuring considerable redundancy over the minimum four satellites needed for a position. <div class="mw-heading mw-heading3"><h3 id="Control_segment">Control segment</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=14" title="Edit section: Control segment">edit</a>]</div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:GPS_monitor_station.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/22/GPS_monitor_station.jpg/180px-GPS_monitor_station.jpg" decoding="async" width="180" height="120" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/22/GPS_monitor_station.jpg/270px-GPS_monitor_station.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/22/GPS_monitor_station.jpg/360px-GPS_monitor_station.jpg 2x" data-file-width="3008" data-file-height="2000" /></a><figcaption>Ground monitor station used from 1984 to 2007, on display at the <a href="/wiki/Air_Force_Space_and_Missile_Museum" class="mw-redirect" title="Air Force Space and Missile Museum">Air Force Space and Missile Museum</a></figcaption></figure> The control segment (CS) is composed of: <ol><li>a master control station (MCS),</li> <li>an alternative master control station,</li> <li>four dedicated ground antennas, and</li> <li>six dedicated monitor stations.</li></ol> The MCS can also access <a href="/wiki/Satellite_Control_Network" title="Satellite Control Network">Satellite Control Network</a> (SCN) ground antennas (for additional command and control capability) and NGA (<a href="/wiki/National_Geospatial-Intelligence_Agency" title="National Geospatial-Intelligence Agency">National Geospatial-Intelligence Agency</a>) monitor stations. The flight paths of the satellites are tracked by dedicated U.S. Space Force monitoring stations in Hawaii, <a href="/wiki/Kwajalein_Atoll" title="Kwajalein Atoll">Kwajalein Atoll</a>, <a href="/wiki/Ascension_Island" title="Ascension Island">Ascension Island</a>, <a href="/wiki/Diego_Garcia" title="Diego Garcia">Diego Garcia</a>, <a href="/wiki/Colorado_Springs,_Colorado" title="Colorado Springs, Colorado">Colorado Springs, Colorado</a> and <a href="/wiki/Cape_Canaveral" title="Cape Canaveral">Cape Canaveral</a>, Florida, along with shared NGA monitor stations operated in England, Argentina, Ecuador, Bahrain, Australia and Washington, DC.<a href="#cite_note-94">[93]</a> The tracking information is sent to the MCS at <a href="/wiki/Schriever_Space_Force_Base" title="Schriever Space Force Base">Schriever Space Force Base</a> 25 km (16 mi) ESE of Colorado Springs, which is operated by the <a href="/wiki/2nd_Space_Operations_Squadron" class="mw-redirect" title="2nd Space Operations Squadron">2nd Space Operations Squadron</a> (2 SOPS) of the U.S. Space Force. Then 2 SOPS contacts each GPS satellite regularly with a navigational update using dedicated or shared (AFSCN) ground antennas (GPS dedicated ground antennas are located at <a href="/wiki/Kwajalein" class="mw-redirect" title="Kwajalein">Kwajalein</a>, <a href="/wiki/Ascension_Island" title="Ascension Island">Ascension Island</a>, <a href="/wiki/Diego_Garcia" title="Diego Garcia">Diego Garcia</a>, and <a href="/wiki/Cape_Canaveral" title="Cape Canaveral">Cape Canaveral</a>). These updates synchronize the atomic clocks on board the satellites to within a few <a href="/wiki/Nanosecond" title="Nanosecond">nanoseconds</a> of each other, and adjust the <a href="/wiki/Ephemeris" title="Ephemeris">ephemeris</a> of each satellite's internal orbital model. The updates are created by a <a href="/wiki/Kalman_filter" title="Kalman filter">Kalman filter</a> that uses inputs from the ground monitoring stations, <a href="/wiki/Space_weather" title="Space weather">space weather</a> information, and various other inputs.<a href="#cite_note-95">[94]</a> When a satellite's orbit is being adjusted, the satellite is marked unhealthy, so receivers do not use it. After the maneuver, engineers track the new orbit from the ground, upload the new ephemeris, and mark the satellite healthy again. The operation control segment (OCS) currently serves as the control segment of record. It provides the operational capability that supports GPS users and keeps the GPS operational and performing within specification. OCS replaced the 1970s-era mainframe computer at Schriever Air Force Base in September 2007. After installation, the system helped enable upgrades and provide a foundation for a new security architecture that supported U.S. armed forces. OCS will continue to be the ground control system of record until the new segment, Next Generation GPS Operation Control System<a href="#cite_note-losangelesmil-8">[8]</a> (OCX), is fully developed and functional. The U.S. Department of Defense has claimed that the new capabilities provided by OCX will be the cornerstone for enhancing GPS's mission capabilities, enabling U.S. Space Force to enhance GPS operational services to U.S. combat forces, civil partners and domestic and international users.<a href="#cite_note-96">[95]</a><a href="#cite_note-97">[96]</a> The GPS OCX program also will reduce cost, schedule and technical risk. It is designed to provide 50%<a href="#cite_note-98">[97]</a> sustainment cost savings through efficient software architecture and Performance-Based Logistics. In addition, GPS OCX is expected to cost millions of dollars less than the cost to upgrade OCS while providing four times the capability. The GPS OCX program represents a critical part of GPS modernization and provides information assurance improvements over the current GPS OCS program. <ul><li>OCX will have the ability to control and manage GPS legacy satellites as well as the next generation of GPS III satellites, while enabling the full array of military signals.</li> <li>Built on a flexible architecture that can rapidly adapt to changing needs of GPS users allowing immediate access to GPS data and constellation status through secure, accurate and reliable information.</li> <li>Provides the warfighter with more secure, actionable and predictive information to enhance situational awareness.</li> <li>Enables new modernized signals (L1C, L2C, and L5) and has M-code capability, which the legacy system is unable to do.</li> <li>Provides significant information assurance improvements over the current program including detecting and preventing cyber attacks, while isolating, containing and operating during such attacks.</li> <li>Supports higher volume near real-time command and control capabilities and abilities.</li></ul> On September 14, 2011,<a href="#cite_note-99">[98]</a> the U.S. Air Force announced the completion of GPS OCX Preliminary Design Review and confirmed that the OCX program is ready for the next phase of development. The GPS OCX program missed major milestones and pushed its launch into 2021, 5 years past the original deadline. According to the Government Accounting Office in 2019, the 2021 deadline looked shaky.<a href="#cite_note-100">[99]</a> The project remained delayed in 2023, and was (as of June 2023) 73% over its original estimated budget.<a href="#cite_note-101">[100]</a><a href="#cite_note-102">[101]</a> In late 2023, Frank Calvelli, the assistant secretary of the Air Force for space acquisitions and integration, stated that the project was estimated to go live some time during the summer of 2024.<a href="#cite_note-103">[102]</a> <div class="mw-heading mw-heading3"><h3 id="User_segment">User segment</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=15" title="Edit section: User segment">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/GPS_navigation_device" class="mw-redirect" title="GPS navigation device">GPS navigation device</a></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:GPS_Receivers.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6b/GPS_Receivers.jpg/180px-GPS_Receivers.jpg" decoding="async" width="180" height="111" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6b/GPS_Receivers.jpg/270px-GPS_Receivers.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6b/GPS_Receivers.jpg/360px-GPS_Receivers.jpg 2x" data-file-width="1000" data-file-height="619" /></a><figcaption>GPS receivers come in a variety of formats, from devices integrated into cars, phones, and watches, to dedicated devices such as those shown above.</figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Leica_WM_101_at_the_National_Science_Museum_at_Maynooth.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/02/Leica_WM_101_at_the_National_Science_Museum_at_Maynooth.JPG/220px-Leica_WM_101_at_the_National_Science_Museum_at_Maynooth.JPG" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/02/Leica_WM_101_at_the_National_Science_Museum_at_Maynooth.JPG/330px-Leica_WM_101_at_the_National_Science_Museum_at_Maynooth.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/02/Leica_WM_101_at_the_National_Science_Museum_at_Maynooth.JPG/440px-Leica_WM_101_at_the_National_Science_Museum_at_Maynooth.JPG 2x" data-file-width="3872" data-file-height="2592" /></a><figcaption>The first portable GPS survey unit, a Leica WM 101, displayed at the <a href="/w/index.php?title=Irish_National_Science_Museum&action=edit&redlink=1" class="new" title="Irish National Science Museum (page does not exist)">Irish National Science Museum</a> at <a href="/wiki/Maynooth" title="Maynooth">Maynooth</a></figcaption></figure> The user segment (US) is composed of hundreds of thousands of U.S. and allied military users of the secure GPS Precise Positioning Service, and tens of millions of civil, commercial and scientific users of the Standard Positioning Service. In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and a highly stable clock (often a <a href="/wiki/Crystal_oscillator" title="Crystal oscillator">crystal oscillator</a>). They may also include a display for providing location and speed information to the user. GPS receivers may include an input for differential corrections, using the <a href="/wiki/RTCM" class="mw-redirect" title="RTCM">RTCM</a> SC-104 format. This is typically in the form of an <a href="/wiki/RS-232" title="RS-232">RS-232</a> port at 4,800 bit/s speed. Data is actually sent at a much lower rate, which limits the accuracy of the signal sent using RTCM.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] Receivers with internal DGPS receivers can outperform those using external RTCM data.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] As of 2006<a class="external text" href="https://en.wikipedia.org/w/index.php?title=Global_Positioning_System&action=edit">[update]</a>, even low-cost units commonly include <a href="/wiki/Wide_Area_Augmentation_System" title="Wide Area Augmentation System">Wide Area Augmentation System</a> (WAAS) receivers. <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:SiRF_Star_III_%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%B0_GPS_%D0%BF%D1%80%D0%B8%D1%91%D0%BC%D0%BD%D0%B8%D0%BA%D0%B5_%D1%81_%D0%B8%D0%BD%D1%82%D0%B5%D0%B3%D1%80%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B9_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7b/SiRF_Star_III_%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%B0_GPS_%D0%BF%D1%80%D0%B8%D1%91%D0%BC%D0%BD%D0%B8%D0%BA%D0%B5_%D1%81_%D0%B8%D0%BD%D1%82%D0%B5%D0%B3%D1%80%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B9_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9.jpg/180px-SiRF_Star_III_%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%B0_GPS_%D0%BF%D1%80%D0%B8%D1%91%D0%BC%D0%BD%D0%B8%D0%BA%D0%B5_%D1%81_%D0%B8%D0%BD%D1%82%D0%B5%D0%B3%D1%80%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B9_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9.jpg" decoding="async" width="180" height="79" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7b/SiRF_Star_III_%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%B0_GPS_%D0%BF%D1%80%D0%B8%D1%91%D0%BC%D0%BD%D0%B8%D0%BA%D0%B5_%D1%81_%D0%B8%D0%BD%D1%82%D0%B5%D0%B3%D1%80%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B9_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9.jpg/270px-SiRF_Star_III_%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%B0_GPS_%D0%BF%D1%80%D0%B8%D1%91%D0%BC%D0%BD%D0%B8%D0%BA%D0%B5_%D1%81_%D0%B8%D0%BD%D1%82%D0%B5%D0%B3%D1%80%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B9_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7b/SiRF_Star_III_%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%B0_GPS_%D0%BF%D1%80%D0%B8%D1%91%D0%BC%D0%BD%D0%B8%D0%BA%D0%B5_%D1%81_%D0%B8%D0%BD%D1%82%D0%B5%D0%B3%D1%80%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B9_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9.jpg/360px-SiRF_Star_III_%D0%BE%D1%81%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%B0_GPS_%D0%BF%D1%80%D0%B8%D1%91%D0%BC%D0%BD%D0%B8%D0%BA%D0%B5_%D1%81_%D0%B8%D0%BD%D1%82%D0%B5%D0%B3%D1%80%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B9_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9.jpg 2x" data-file-width="2816" data-file-height="1242" /></a><figcaption>A typical GPS receiver with integrated antenna</figcaption></figure> Many GPS receivers can relay position data to a PC or other device using the <a href="/wiki/NMEA_0183" title="NMEA 0183">NMEA 0183</a> protocol. Although this protocol is officially defined by the National Marine Electronics Association (NMEA),<a href="#cite_note-104">[103]</a> references to this protocol have been compiled from public records, allowing open source tools like <a href="/wiki/Gpsd" title="Gpsd">gpsd</a> to read the protocol without violating intellectual property laws.[<a href="/wiki/Wikipedia:Please_clarify" title="Wikipedia:Please clarify">clarification needed</a>] Other proprietary protocols exist as well, such as the <a href="/wiki/SiRF" title="SiRF">SiRF</a> and <a href="/wiki/MediaTek" title="MediaTek">MTK</a> protocols. Receivers can interface with other devices using methods including a serial connection, <a href="/wiki/Universal_Serial_Bus" class="mw-redirect" title="Universal Serial Bus">USB</a>, or <a href="/wiki/Bluetooth" title="Bluetooth">Bluetooth</a>. <div class="mw-heading mw-heading2"><h2 id="Applications">Applications</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=16" title="Edit section: Applications">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></div></td><td class="mbox-text"><div class="mbox-text-span">This section needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a>. Please help <a href="/wiki/Special:EditPage/Global_Positioning_System" title="Special:EditPage/Global Positioning System">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed. (March 2015) (<a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a>)</div></td></tr></tbody></table> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/GNSS_applications" title="GNSS applications">GNSS applications</a></div> While originally a military project, GPS is considered a <a href="/wiki/Dual-use_technology" title="Dual-use technology">dual-use technology</a>, meaning it has significant civilian applications as well. GPS has become a widely deployed and useful tool for commerce, scientific uses, tracking, and surveillance. GPS's accurate time facilitates everyday activities such as banking, mobile phone operations, and even the control of power grids by allowing well synchronized hand-off switching.<a href="#cite_note-gps.gov-82">[81]</a> <div class="mw-heading mw-heading3"><h3 id="Civilian">Civilian</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=17" title="Edit section: Civilian">edit</a>]</div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:GPS_roof_antenna_dsc06160.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4a/GPS_roof_antenna_dsc06160.jpg/180px-GPS_roof_antenna_dsc06160.jpg" decoding="async" width="180" height="305" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4a/GPS_roof_antenna_dsc06160.jpg/270px-GPS_roof_antenna_dsc06160.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4a/GPS_roof_antenna_dsc06160.jpg/360px-GPS_roof_antenna_dsc06160.jpg 2x" data-file-width="760" data-file-height="1288" /></a><figcaption>This <a href="/wiki/Antenna_(radio)" title="Antenna (radio)">antenna</a> is mounted on the roof of a hut containing a scientific experiment needing precise timing.</figcaption></figure> Many civilian applications use one or more of GPS's three basic components: absolute location, relative movement, and time transfer. <ul><li><a href="/wiki/Amateur_radio" title="Amateur radio">Amateur radio</a>: clock synchronization required for several digital modes such as <a href="/wiki/FT8" title="FT8">FT8</a>, FT4 and JS8; also used with <a href="/wiki/Automatic_Packet_Reporting_System" title="Automatic Packet Reporting System">APRS</a> for position reporting; is often critical during emergency and disaster communications support.</li> <li><a href="/wiki/Atmosphere" title="Atmosphere">Atmosphere</a>: studying the <a href="/wiki/Troposphere" title="Troposphere">troposphere</a> delays (recovery of the water vapor content) and <a href="/wiki/Ionosphere" title="Ionosphere">ionosphere</a> delays (recovery of the number of free electrons).<a href="#cite_note-105">[104]</a> Recovery of Earth surface displacements due to the atmospheric pressure loading.<a href="#cite_note-106">[105]</a></li> <li><a href="/wiki/Astronomy" title="Astronomy">Astronomy</a>: both positional and <a href="/wiki/Clock_synchronization" title="Clock synchronization">clock synchronization</a> data is used in <a href="/wiki/Astrometry" title="Astrometry">astrometry</a> and <a href="/wiki/Celestial_mechanics" title="Celestial mechanics">celestial mechanics</a> and precise orbit determination.<a href="#cite_note-107">[106]</a> GPS is also used in both <a href="/wiki/Amateur_astronomy" title="Amateur astronomy">amateur astronomy</a> with <a href="/wiki/GoTo_(telescopes)" title="GoTo (telescopes)">small telescopes</a> as well as by professional observatories for finding <a href="/wiki/Extrasolar_planet" class="mw-redirect" title="Extrasolar planet">extrasolar planets</a>.</li> <li><a href="/wiki/Automated_vehicle" class="mw-redirect" title="Automated vehicle">Automated vehicle</a>: applying location and routes for cars and trucks to function without a human driver.</li> <li><a href="/wiki/Cartography" title="Cartography">Cartography</a>: both civilian and military cartographers use GPS extensively.</li> <li><a href="/wiki/Cellular_telephony" class="mw-redirect" title="Cellular telephony">Cellular telephony</a>: clock synchronization enables time transfer, which is critical for synchronizing its spreading codes with other base stations to facilitate inter-cell handoff and support hybrid GPS/cellular position detection for <a href="/wiki/E911#Wireless_enhanced_911" class="mw-redirect" title="E911">mobile emergency calls</a> and other applications. The first <a href="/wiki/Mobile_GPS_navigation" class="mw-redirect" title="Mobile GPS navigation">handsets with integrated GPS</a> launched in the late 1990s. The U.S. <a href="/wiki/Federal_Communications_Commission" title="Federal Communications Commission">Federal Communications Commission</a> (FCC) mandated the feature in either the handset or in the towers (for use in triangulation) in 2002 so emergency services could locate 911 callers. Third-party software developers later gained access to GPS APIs from <a href="/wiki/Nextel" title="Nextel">Nextel</a> upon launch, followed by <a href="/wiki/Sprint_Nextel" class="mw-redirect" title="Sprint Nextel">Sprint</a> in 2006, and <a href="/wiki/Verizon" title="Verizon">Verizon</a> soon thereafter.</li> <li><a href="/wiki/Clock_synchronization" title="Clock synchronization">Clock synchronization</a>: the accuracy of GPS time signals (±10 ns)<a href="#cite_note-108">[107]</a> is second only to the atomic clocks they are based on, and is used in applications such as <a href="/wiki/GPS_disciplined_oscillator" title="GPS disciplined oscillator">GPS disciplined oscillators</a>.</li> <li><a href="/wiki/Disaster_relief" class="mw-redirect" title="Disaster relief">Disaster relief</a>/<a href="/wiki/Emergency_service" title="Emergency service">emergency services</a>: many emergency services depend upon GPS for location and timing capabilities.</li> <li>GPS-equipped <a href="/wiki/Radiosonde" title="Radiosonde">radiosondes</a> and <a href="/wiki/Dropsonde" title="Dropsonde">dropsondes</a>: measure and calculate the atmospheric pressure, wind speed and direction up to 27 km (89,000 ft) from the Earth's surface.</li> <li><a href="/wiki/Radio_occultation" title="Radio occultation">Radio occultation</a> for weather and atmospheric science applications.<a href="#cite_note-109">[108]</a></li> <li><a href="/wiki/Fleet_tracking" class="mw-redirect" title="Fleet tracking">Fleet tracking</a>: used to identify, locate and maintain contact reports with one or more <a href="/wiki/Fleet_vehicle" title="Fleet vehicle">fleet</a> vehicles in real-time.</li> <li><a href="/wiki/Geodesy" title="Geodesy">Geodesy</a>: determination of <a href="/wiki/Earth_orientation_parameters" title="Earth orientation parameters">Earth orientation parameters</a> including the daily and sub-daily polar motion,<a href="#cite_note-110">[109]</a> and length-of-day variabilities,<a href="#cite_note-111">[110]</a> Earth's center-of-mass – geocenter motion,<a href="#cite_note-112">[111]</a> and low-degree gravity field parameters.<a href="#cite_note-113">[112]</a></li> <li><a href="/wiki/Geofence" title="Geofence">Geofencing</a>: <a href="/wiki/Vehicle_tracking_system" title="Vehicle tracking system">vehicle tracking systems</a>, <a href="/wiki/Handheld_tracker" class="mw-redirect" title="Handheld tracker">person tracking systems</a>, and <a href="/wiki/Tracking_collar" class="mw-redirect" title="Tracking collar">pet tracking</a> systems use GPS to locate devices that are attached to or carried by a person, vehicle, or pet. The application can provide continuous tracking and send notifications if the target leaves a designated (or "fenced-in") area.<a href="#cite_note-Rouse-114">[113]</a></li> <li><a href="/wiki/Geotagging" title="Geotagging">Geotagging</a>: applies location coordinates to digital objects such as photographs (in <a href="/wiki/Exif" title="Exif">Exif</a> data) and other documents for purposes such as creating map overlays with devices like <a href="/wiki/Nikon_GP-1" title="Nikon GP-1">Nikon GP-1</a>.</li> <li><a href="/wiki/GPS_aircraft_tracking" title="GPS aircraft tracking">GPS aircraft tracking</a></li> <li><a href="/w/index.php?title=GPS_for_mining&action=edit&redlink=1" class="new" title="GPS for mining (page does not exist)">GPS for mining</a>: the use of RTK GPS has significantly improved several mining operations such as drilling, shoveling, vehicle tracking, and surveying. RTK GPS provides centimeter-level positioning accuracy.<a href="#cite_note-115">[114]</a><a href="#cite_note-116">[115]</a></li> <li><a href="/w/index.php?title=GPS_data_mining&action=edit&redlink=1" class="new" title="GPS data mining (page does not exist)">GPS data mining</a>: It is possible to aggregate GPS data from multiple users to understand movement patterns, common trajectories and interesting locations.<a href="#cite_note-117">[116]</a> GPS data is today used in transportation and disaster engineering to forecast mobility in normal and evacuation situations (e.g., hurricanes, wildfires, earthquakes).<a href="#cite_note-118">[117]</a><a href="#cite_note-119">[118]</a><a href="#cite_note-120">[119]</a><a href="#cite_note-121">[120]</a></li> <li><a href="/wiki/GPS_tour" class="mw-redirect" title="GPS tour">GPS tours</a>: location determines what content to display; for instance, information about an approaching point of interest.</li> <li><a href="/wiki/Mental_health" title="Mental health">Mental health</a>: tracking mental health functioning and sociability.<a href="#cite_note-122">[121]</a></li> <li><a href="/wiki/Navigation" title="Navigation">Navigation</a>: navigators value digitally precise velocity and orientation measurements, as well as precise positions in real-time with a support of orbit and clock corrections.<a href="#cite_note-123">[122]</a></li> <li><a href="/wiki/Orbit" title="Orbit">Orbit</a> determination of low-orbiting satellites with GPS receiver installed on board, such as <a href="/wiki/GOCE" title="GOCE">GOCE</a>,<a href="#cite_note-124">[123]</a> <a href="/wiki/GRACE_and_GRACE-FO" title="GRACE and GRACE-FO">GRACE</a>, <a href="/wiki/Jason-1" title="Jason-1">Jason-1</a>, <a href="/wiki/Jason-2" class="mw-redirect" title="Jason-2">Jason-2</a>, <a href="/wiki/TerraSAR-X" title="TerraSAR-X">TerraSAR-X</a>, <a href="/wiki/TanDEM-X" title="TanDEM-X">TanDEM-X</a>, <a href="/wiki/CHAMP_(satellite)" title="CHAMP (satellite)">CHAMP</a>, <a href="/wiki/Sentinel-3" title="Sentinel-3">Sentinel-3</a>,<a href="#cite_note-125">[124]</a> and some cubesats, e.g., <a href="/wiki/CubETH" title="CubETH">CubETH</a>.</li> <li><a href="/wiki/Phasor_measurement_unit" title="Phasor measurement unit">Phasor measurements</a>: GPS enables highly accurate timestamping of power system measurements, making it possible to compute <a href="/wiki/Phasor_measurement_unit" title="Phasor measurement unit">phasors</a>.</li> <li><a href="/wiki/Recreation" title="Recreation">Recreation</a>: for example, <a href="/wiki/Geocaching" title="Geocaching">Geocaching</a>, <a href="/wiki/Geodashing" class="mw-redirect" title="Geodashing">Geodashing</a>, <a href="/wiki/GPS_drawing" title="GPS drawing">GPS drawing</a>, <a href="/wiki/Waymarking" class="mw-redirect" title="Waymarking">waymarking</a>, and other kinds of <a href="/wiki/Location-based_game" title="Location-based game">location based mobile games</a> such as <a href="/wiki/Pok%C3%A9mon_Go" title="Pokémon Go">Pokémon Go</a>.</li> <li><a href="/wiki/Reference_frames" class="mw-redirect" title="Reference frames">Reference frames</a>: realization and densification of the terrestrial reference frames<a href="#cite_note-126">[125]</a> in the framework of Global Geodetic Observing System. Co-location in space between <a href="/wiki/Satellite_laser_ranging" title="Satellite laser ranging">Satellite laser ranging</a><a href="#cite_note-127">[126]</a> and microwave observations<a href="#cite_note-128">[127]</a> for deriving global geodetic parameters.<a href="#cite_note-129">[128]</a><a href="#cite_note-130">[129]</a></li> <li><a href="/wiki/Robotics" title="Robotics">Robotics</a>: self-navigating, autonomous robots using GPS sensors,<a href="#cite_note-131">[130]</a> which calculate latitude, longitude, time, speed, and heading.</li> <li><a href="/wiki/Sport" title="Sport">Sport</a>: used in football and rugby for the control and analysis of the training load.<a href="#cite_note-LiveViewGPS_2012-09-06-132">[131]</a></li> <li><a href="/wiki/Surveying" title="Surveying">Surveying</a>: surveyors use absolute locations to make maps and determine property boundaries.</li> <li><a href="/wiki/Tectonics" title="Tectonics">Tectonics</a>: GPS enables direct fault motion measurement of <a href="/wiki/Earthquakes" class="mw-redirect" title="Earthquakes">earthquakes</a>. Between earthquakes GPS can be used to measure <a href="/wiki/Crust_(geology)" title="Crust (geology)">crustal</a> motion and deformation<a href="#cite_note-133">[132]</a> to estimate seismic strain buildup for creating <a href="/wiki/Seismic_hazard" title="Seismic hazard">seismic hazard</a> maps.</li> <li><a href="/wiki/Telematics" title="Telematics">Telematics</a>: GPS technology integrated with computers and mobile communications technology in <a href="/wiki/Automotive_navigation_system" title="Automotive navigation system">automotive navigation systems</a>.</li></ul> <div class="mw-heading mw-heading4"><h4 id="Restrictions_on_civilian_use">Restrictions on civilian use</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=18" title="Edit section: Restrictions on civilian use">edit</a>]</div> The U.S. government controls the export of some civilian receivers. All GPS receivers capable of functioning above 60,000 ft (18 km) above sea level and 1,000 kn (500 m/s; 2,000 km/h; 1,000 mph), or designed or modified for use with unmanned missiles and aircraft, are classified as <a href="/wiki/United_States_Munitions_List" title="United States Munitions List">munitions</a> (weapons)—which means they require <a href="/wiki/United_States_Department_of_State" title="United States Department of State">State Department</a> export licenses.<a href="#cite_note-134">[133]</a> This rule applies even to otherwise purely civilian units that only receive the L1 frequency and the C/A (Coarse/Acquisition) code. Disabling operation above these limits exempts the receiver from classification as a munition. Vendor interpretations differ. The rule refers to operation at both the target altitude and speed, but some receivers stop operating even when stationary. This has caused problems with some amateur radio balloon launches that regularly reach 30 km (100,000 feet). These limits only apply to units or components exported from the United States. A growing trade in various components exists, including GPS units from other countries. These are expressly sold as <a href="/wiki/International_Traffic_in_Arms_Regulations" title="International Traffic in Arms Regulations">ITAR</a>-free. <div class="mw-heading mw-heading3"><h3 id="Military">Military</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=19" title="Edit section: Military">edit</a>]</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Exelis_SINCGARS_RT-1523G.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Exelis_SINCGARS_RT-1523G.jpg/220px-Exelis_SINCGARS_RT-1523G.jpg" decoding="async" width="220" height="148" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Exelis_SINCGARS_RT-1523G.jpg/330px-Exelis_SINCGARS_RT-1523G.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Exelis_SINCGARS_RT-1523G.jpg/440px-Exelis_SINCGARS_RT-1523G.jpg 2x" data-file-width="800" data-file-height="538" /></a><figcaption>AN/PRC-119F SINCGARS radio, which requires accurate clock time supplied by an external GPS system to enable frequency hopping operation with other radios</figcaption></figure><figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:US_Navy_030319-N-4142G-020_Ordnance_handlers_assemble_Joint_Direct_Attack_Munition_(JDAM)_bombs_in_the_forward_mess_decks.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cf/US_Navy_030319-N-4142G-020_Ordnance_handlers_assemble_Joint_Direct_Attack_Munition_%28JDAM%29_bombs_in_the_forward_mess_decks.jpg/220px-US_Navy_030319-N-4142G-020_Ordnance_handlers_assemble_Joint_Direct_Attack_Munition_%28JDAM%29_bombs_in_the_forward_mess_decks.jpg" decoding="async" width="220" height="144" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cf/US_Navy_030319-N-4142G-020_Ordnance_handlers_assemble_Joint_Direct_Attack_Munition_%28JDAM%29_bombs_in_the_forward_mess_decks.jpg/330px-US_Navy_030319-N-4142G-020_Ordnance_handlers_assemble_Joint_Direct_Attack_Munition_%28JDAM%29_bombs_in_the_forward_mess_decks.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cf/US_Navy_030319-N-4142G-020_Ordnance_handlers_assemble_Joint_Direct_Attack_Munition_%28JDAM%29_bombs_in_the_forward_mess_decks.jpg/440px-US_Navy_030319-N-4142G-020_Ordnance_handlers_assemble_Joint_Direct_Attack_Munition_%28JDAM%29_bombs_in_the_forward_mess_decks.jpg 2x" data-file-width="2000" data-file-height="1312" /></a><figcaption>Attaching a GPS guidance kit to an <a href="/wiki/Unguided_bomb" title="Unguided bomb">unguided bomb</a>, March 2003</figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:XM982_Excalibur_inert.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5d/XM982_Excalibur_inert.jpg/220px-XM982_Excalibur_inert.jpg" decoding="async" width="220" height="129" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5d/XM982_Excalibur_inert.jpg/330px-XM982_Excalibur_inert.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5d/XM982_Excalibur_inert.jpg/440px-XM982_Excalibur_inert.jpg 2x" data-file-width="510" data-file-height="299" /></a><figcaption><a href="/wiki/M982_Excalibur" title="M982 Excalibur">M982 Excalibur</a> GPS-guided <a href="/wiki/Artillery_shell" class="mw-redirect" title="Artillery shell">artillery shell</a></figcaption></figure> As of 2009, military GPS applications include: <ul><li>Navigation: Soldiers use GPS to find objectives, even in the dark or in unfamiliar territory, and to coordinate troop and supply movement. In the United States armed forces, commanders use the Commander's Digital Assistant and lower ranks use the Soldier Digital Assistant.<a href="#cite_note-135">[134]</a></li> <li>Frequency-Hopping Radio Clock Coordination: Military radio systems using <a href="/wiki/Frequency-hopping_spread_spectrum" title="Frequency-hopping spread spectrum">frequency hopping</a> modes, such as <a href="/wiki/SINCGARS" title="SINCGARS">SINCGARS</a> and <a href="/wiki/Have_Quick" title="Have Quick">HAVEQUICK</a>, require all radios within a network to have the same time input to their internal clocks (+/-4 seconds in the case of SINCGARS) to be on the correct frequency at a given time. Military GPS receivers, such as the <a href="/wiki/Precision_Lightweight_GPS_Receiver" title="Precision Lightweight GPS Receiver">Precision Lightweight GPS Receiver</a> (PLGR) and <a href="/wiki/Defense_Advanced_GPS_Receiver" class="mw-redirect" title="Defense Advanced GPS Receiver">Defense Advanced GPS Receiver</a> (DAGR), are used by <a href="/wiki/Radio_operator" title="Radio operator">radio operators</a> within a radio network to properly input an accurate time to said radios internal clock. More modern military radios have internal GPS receivers that synchronize the internal clock automatically.</li> <li>Target tracking: Various military weapons systems use GPS to track potential ground and air targets before flagging them as hostile.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] These weapon systems pass target coordinates to <a href="/wiki/Precision-guided_munition" title="Precision-guided munition">precision-guided munitions</a> to allow them to engage targets accurately. Military aircraft, particularly in <a href="/wiki/Air-to-ground" class="mw-redirect" title="Air-to-ground">air-to-ground</a> roles, use GPS to find targets.</li> <li>Missile and projectile guidance: GPS allows accurate targeting of various military weapons including <a href="/wiki/ICBM" class="mw-redirect" title="ICBM">ICBMs</a>, <a href="/wiki/Cruise_missile" title="Cruise missile">cruise missiles</a>, <a href="/wiki/Precision-guided_munition" title="Precision-guided munition">precision-guided munitions</a> and <a href="/wiki/Artillery_shell" class="mw-redirect" title="Artillery shell">artillery shells</a>. Embedded GPS receivers able to withstand accelerations of 12,000 <a href="/wiki/G-force" title="G-force">g</a><a href="#cite_note-dote-fy2003-69-136">[135]</a> or about 118 km/s2 (260,000 mph/s) have been developed for use in 155-millimeter (6.1 in) <a href="/wiki/Howitzer" title="Howitzer">howitzer</a> shells.<a href="#cite_note-dote-fy2010-xm982-137">[136]</a></li> <li>Search and rescue.</li> <li>Reconnaissance: Patrol movement can be managed more closely.</li> <li>GPS satellites carry a set of nuclear detonation detectors consisting of an optical sensor called a <a href="/wiki/Bhangmeter" title="Bhangmeter">bhangmeter</a>, an X-ray sensor, a dosimeter, and an electromagnetic pulse (EMP) sensor (W-sensor), that form a major portion of the <a href="/wiki/United_States_Nuclear_Detonation_Detection_System" class="mw-redirect" title="United States Nuclear Detonation Detection System">United States Nuclear Detonation Detection System</a>.<a href="#cite_note-138">[137]</a><a href="#cite_note-139">[138]</a> General William Shelton has stated that future satellites may drop this feature to save money.<a href="#cite_note-140">[139]</a></li></ul> GPS type navigation was first used in war in the <a href="/wiki/Gulf_War" title="Gulf War">1991 Persian Gulf War</a>, before GPS was fully developed in 1995, to assist <a href="/wiki/Coalition_of_the_Gulf_War" title="Coalition of the Gulf War">Coalition Forces</a> to navigate and perform maneuvers in the war. The war also demonstrated the vulnerability of GPS to being <a href="/wiki/Radio_jamming" title="Radio jamming">jammed</a>, when Iraqi forces installed jamming devices on likely targets that emitted radio noise, disrupting reception of the weak GPS signal.<a href="#cite_note-141">[140]</a> GPS's vulnerability to jamming is a threat that continues to grow as jamming equipment and experience grows.<a href="#cite_note-142">[141]</a><a href="#cite_note-143">[142]</a> GPS signals have been reported to have been jammed many times over the years for military purposes. Russia seems to have several objectives for this approach, such as intimidating neighbors while undermining confidence in their reliance on American systems, promoting their GLONASS alternative, disrupting Western military exercises, and protecting assets from drones.<a href="#cite_note-144">[143]</a> China uses jamming to discourage US surveillance aircraft near the contested <a href="/wiki/Spratly_Islands" title="Spratly Islands">Spratly Islands</a>.<a href="#cite_note-145">[144]</a> <a href="/wiki/North_Korea" title="North Korea">North Korea</a> has mounted several major jamming operations near its border with South Korea and offshore, disrupting flights, shipping and fishing operations.<a href="#cite_note-146">[145]</a> Iranian Armed Forces disrupted the civilian airliner plane Flight <a href="/wiki/PS752" class="mw-redirect" title="PS752">PS752</a>'s GPS when it shot down the aircraft.<a href="#cite_note-147">[146]</a><a href="#cite_note-148">[147]</a> In the <a href="/wiki/Russo-Ukrainian_War" title="Russo-Ukrainian War">Russo-Ukrainian War</a>, GPS-guided munitions provided to Ukraine by NATO countries experienced significant failure rates as a result of Russian electronic warfare. Excalibur artillery shells efficiency rate hitting targets dropped from 70% to 6% as Russia adapted its electronic warfare activities.<a href="#cite_note-149">[148]</a> <div class="mw-heading mw-heading3"><h3 id="Timekeeping">Timekeeping </h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=20" title="Edit section: Timekeeping">edit</a>]</div> <div class="mw-heading mw-heading4"><h4 id="Leap_seconds">Leap seconds</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=21" title="Edit section: Leap seconds">edit</a>]</div> While most clocks derive their time from <a href="/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time">Coordinated Universal Time</a> (UTC), the atomic clocks on the satellites are set to GPS time. The difference is that GPS time is not corrected to match the rotation of the Earth, so it does not contain new <a href="/wiki/Leap_second" title="Leap second">leap seconds</a> or other corrections that are periodically added to UTC. GPS time was set to match UTC in 1980, but has since diverged. The lack of corrections means that GPS time remains at a constant offset with <a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a> (TAI) (TAI – GPS = 19 seconds). Periodic corrections are performed to the on-board clocks to keep them synchronized with ground clocks.<a href="#cite_note-NAVGPS-80">[79]</a>: Section 1.2.2  The GPS navigation message includes the difference between GPS time and UTC. As of January 2017,<a class="external text" href="https://en.wikipedia.org/w/index.php?title=Global_Positioning_System&action=edit">[update]</a> GPS time is 18 seconds ahead of UTC because of the leap second added to UTC on December 31, 2016.<a href="#cite_note-150">[149]</a> Receivers subtract this offset from GPS time to calculate UTC and specific time zone values. New GPS units may not show the correct UTC time until after receiving the UTC offset message. The GPS-UTC offset field can accommodate 255 leap seconds (eight bits). <div class="mw-heading mw-heading4"><h4 id="Accuracy">Accuracy</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=22" title="Edit section: Accuracy">edit</a>]</div> GPS time is theoretically accurate to about 14 nanoseconds, due to the <a href="/wiki/Clock_drift" title="Clock drift">clock drift</a> relative to <a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a> that the atomic clocks in GPS transmitters experience.<a href="#cite_note-151">[150]</a> Most receivers lose some accuracy in their interpretation of the signals and are only accurate to about 100 nanoseconds.<a href="#cite_note-152">[151]</a><a href="#cite_note-153">[152]</a> <div class="mw-heading mw-heading4"><h4 id="Relativistic_corrections">Relativistic corrections</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=23" title="Edit section: Relativistic corrections">edit</a>]</div> The GPS implements two major corrections to its time signals for relativistic effects: one for relative velocity of satellite and receiver, using the special theory of relativity, and one for the difference in gravitational potential between satellite and receiver, using general relativity. The acceleration of the satellite could also be computed independently as a correction, depending on purpose, but normally the effect is already dealt with in the first two corrections.<a href="#cite_note-154">[153]</a><a href="#cite_note-155">[154]</a> <div class="mw-heading mw-heading4"><h4 id="Format">Format</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=24" title="Edit section: Format">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/GPS_week_number_rollover" title="GPS week number rollover">GPS week number rollover</a></div> As opposed to the year, month, and day format of the <a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian calendar</a>, the GPS date is expressed as a week number and a seconds-into-week number. The week number is transmitted as a ten-<a href="/wiki/Bit" title="Bit">bit</a> field in the C/A and P(Y) navigation messages, and so it becomes zero again every 1,024 weeks (19.6 years). GPS week zero started at 00:00:00 UTC (00:00:19 TAI) on January 6, 1980, and the week number became zero again for the first time at 23:59:47 UTC on August 21, 1999 (00:00:19 TAI on August 22, 1999). It happened the second time at 23:59:42 UTC on April 6, 2019. To determine the current Gregorian date, a GPS receiver must be provided with the approximate date (to within 3,584 days) to correctly translate the GPS date signal. To address this concern in the future the modernized GPS civil navigation (CNAV) message will use a 13-bit field that only repeats every 8,192 weeks (157 years), thus lasting until 2137 (157 years after GPS week zero). <div class="mw-heading mw-heading2"><h2 id="Communication">Communication</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=25" title="Edit section: Communication">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/GPS_signals" title="GPS signals">GPS signals</a></div> The navigational signals transmitted by GPS satellites encode a variety of information including satellite positions, the state of the internal clocks, and the health of the network. These signals are transmitted on two separate carrier frequencies that are common to all satellites in the network. Two different encodings are used: a public encoding that enables lower resolution navigation, and an encrypted encoding used by the U.S. military.<a href="#cite_note-156">[155]</a> <div class="mw-heading mw-heading3"><h3 id="Message_format">Message format</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=26" title="Edit section: Message format">edit</a>]</div> <dl><dd><table class="wikitable" style="float:right; margin:0 0 0.5em 1em;" border="1"> <caption>GPS message format </caption> <tbody><tr> <th>Subframes</th> <th>Description </th></tr> <tr> <td>1</td> <td>Satellite clock, GPS time relationship </td></tr> <tr> <td>2–3</td> <td>Ephemeris (precise satellite orbit) </td></tr> <tr> <td>4–5</td> <td>Almanac component (satellite network synopsis, error correction) </td></tr></tbody></table></dd></dl> Each GPS satellite continuously broadcasts a navigation message on L1 (C/A and P/Y) and L2 (P/Y) frequencies at a rate of 50 bits per second (see <a href="/wiki/Bitrate" class="mw-redirect" title="Bitrate">bitrate</a>). Each complete message takes 750 seconds (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027">12+1⁄2 minutes) to complete. The message structure has a basic format of a 1500-bit-long frame made up of five subframes, each subframe being 300 bits (6 seconds) long. Subframes 4 and 5 are <a href="/wiki/Commutation_(telemetry)" title="Commutation (telemetry)">subcommutated</a> 25 times each, so that a complete data message requires the transmission of 25 full frames. Each subframe consists of ten words, each 30 bits long. Thus, with 300 bits in a subframe times 5 subframes in a frame times 25 frames in a message, each message is 37,500 bits long. At a transmission rate of 50-bit/s, this gives 750 seconds to transmit an entire <a href="/wiki/GPS_Almanac" class="mw-redirect" title="GPS Almanac">almanac message (GPS)</a>. Each 30-second frame begins precisely on the minute or half-minute as indicated by the atomic clock on each satellite.<a href="#cite_note-157">[156]</a> The first subframe of each frame encodes the week number and the time within the week,<a href="#cite_note-158">[157]</a> as well as the data about the health of the satellite. The second and the third subframes contain the <a href="/wiki/Ephemeris" title="Ephemeris">ephemeris</a> – the precise orbit for the satellite. The fourth and fifth subframes contain the almanac, which contains coarse orbit and status information for up to 32 satellites in the constellation as well as data related to error correction. Thus, to obtain an accurate satellite location from this transmitted message, the receiver must demodulate the message from each satellite it includes in its solution for 18 to 30 seconds. To collect all transmitted almanacs, the receiver must demodulate the message for 732 to 750 seconds or <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1154941027">12+1⁄2 minutes.<a href="#cite_note-159">[158]</a> All satellites broadcast at the same frequencies, encoding signals using unique <a href="/wiki/Code-division_multiple_access" title="Code-division multiple access">code-division multiple access</a> (CDMA) so receivers can distinguish individual satellites from each other. The system uses two distinct CDMA encoding types: the coarse/acquisition (C/A) code, which is accessible by the general public, and the precise (P(Y)) code, which is encrypted so that only the U.S. military and other NATO nations who have been given access to the encryption code can access it.<a href="#cite_note-160">[159]</a> The ephemeris is updated every 2 hours and is sufficiently stable for 4 hours, with provisions for updates every 6 hours or longer in non-nominal conditions. The almanac is updated typically every 24 hours. Additionally, data for a few weeks following is uploaded in case of transmission updates that delay data upload.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] <div class="mw-heading mw-heading3"><h3 id="Satellite_frequencies">Satellite frequencies</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=27" title="Edit section: Satellite frequencies">edit</a>]</div> <dl><dd><table class="wikitable" style="float:right; width:30em; margin:0 0 0.5em 1em;" border="1"> <caption>GPS frequency overview<a href="#cite_note-handbook-pent-161">[160]</a>: 607  </caption> <tbody><tr> <th>Band</th> <th>Frequency</th> <th>Description </th></tr> <tr> <td>L1</td> <td>1575.42 MHz</td> <td>Coarse-acquisition (C/A) and encrypted precision (P(Y)) codes, plus the L1 civilian (<a href="/wiki/GPS_signals#L1C" title="GPS signals">L1C</a>) and military (M) codes on Block III and newer satellites. </td></tr> <tr> <td>L2</td> <td>1227.60 MHz</td> <td>P(Y) code, plus the <a href="/wiki/L2C" class="mw-redirect" title="L2C">L2C</a> and military codes on the Block IIR-M and newer satellites. </td></tr> <tr> <td>L3</td> <td>1381.05 MHz</td> <td>Used for nuclear detonation (NUDET) detection. </td></tr> <tr> <td>L4</td> <td>1379.913 MHz</td> <td>Being studied for additional ionospheric correction. </td></tr> <tr> <td>L5</td> <td>1176.45 MHz</td> <td>Used as a civilian safety-of-life (SoL) signal on Block IIF and newer satellites. </td></tr></tbody></table></dd></dl> All satellites broadcast at the same two frequencies, 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal). The satellite network uses a CDMA spread-spectrum technique<a href="#cite_note-handbook-pent-161">[160]</a>: 607  where the low-bitrate message data is encoded with a high-rate <a href="/wiki/Pseudorandom_number_generator" title="Pseudorandom number generator">pseudo-random</a> (PRN) sequence that is different for each satellite. The receiver must be aware of the PRN codes for each satellite to reconstruct the actual message data. The C/A code, for civilian use, transmits data at 1.023 million <a href="/wiki/Chip_(CDMA)" title="Chip (CDMA)">chips</a> per second, whereas the P code, for U.S. military use, transmits at 10.23 million chips per second. The actual internal reference of the satellites is 10.22999999543 MHz to compensate for <a href="/wiki/Theory_of_relativity" title="Theory of relativity">relativistic effects</a><a href="#cite_note-162">[161]</a><a href="#cite_note-163">[162]</a> that make observers on the Earth perceive a different time reference with respect to the transmitters in orbit. The L1 carrier is modulated by both the C/A and P codes, while the L2 carrier is only modulated by the P code.<a href="#cite_note-avionicswest-89">[88]</a> The P code can be encrypted as a so-called P(Y) code that is only available to military equipment with a proper decryption key. Both the C/A and P(Y) codes impart the precise time-of-day to the user. The L3 signal at a frequency of 1.38105 GHz is used to transmit data from the satellites to ground stations. This data is used by the United States Nuclear Detonation (NUDET) Detection System (USNDS) to detect, locate, and report nuclear detonations (NUDETs) in the Earth's atmosphere and near space.<a href="#cite_note-164">[163]</a> One usage is the enforcement of nuclear test ban treaties. The L4 band at 1.379913 GHz is being studied for additional ionospheric correction.<a href="#cite_note-handbook-pent-161">[160]</a>: 607  The L5 frequency band at 1.17645 GHz was added in the process of <a href="/wiki/GPS_modernization" class="mw-redirect" title="GPS modernization">GPS modernization</a>. This frequency falls into an internationally protected range for aeronautical navigation, promising little or no interference under all circumstances. The first Block IIF satellite that provides this signal was launched in May 2010.<a href="#cite_note-dailytech1-165">[164]</a> On February 5, 2016, the 12th and final Block IIF satellite was launched.<a href="#cite_note-166">[165]</a> The L5 consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. "L5, the third civil GPS signal, will eventually support safety-of-life applications for aviation and provide improved availability and accuracy."<a href="#cite_note-167">[166]</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-Update plainlinks metadata ambox ambox-content ambox-Update" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/bd/Ambox_current_red_Asia_Australia.svg/42px-Ambox_current_red_Asia_Australia.svg.png" decoding="async" width="42" height="34" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/bd/Ambox_current_red_Asia_Australia.svg/63px-Ambox_current_red_Asia_Australia.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/bd/Ambox_current_red_Asia_Australia.svg/84px-Ambox_current_red_Asia_Australia.svg.png 2x" data-file-width="360" data-file-height="290" /></div></td><td class="mbox-text"><div class="mbox-text-span">This section needs to be updated. Please help update this article to reflect recent events or newly available information. (May 2021)</div></td></tr></tbody></table> In 2011, a conditional waiver was granted to <a href="/wiki/LightSquared" class="mw-redirect" title="LightSquared">LightSquared</a> to operate a terrestrial broadband service near the L1 band. Although LightSquared had applied for a license to operate in the 1525 to 1559 band as early as 2003 and it was put out for public comment, the FCC asked LightSquared to form a study group with the GPS community to test GPS receivers and identify issues that might arise due to the larger signal power from the LightSquared terrestrial network. The GPS community had not objected to the LightSquared (formerly MSV and SkyTerra) applications until November 2010, when LightSquared applied for a modification to its Ancillary Terrestrial Component (ATC) authorization. This filing (SAT-MOD-20101118-00239) amounted to a request to run several orders of magnitude more power in the same frequency band for terrestrial base stations, essentially repurposing what was supposed to be a "quiet neighborhood" for signals from space as the equivalent of a cellular network. Testing in the first half of 2011 has demonstrated that the effects from the lower 10 MHz of spectrum are minimal to GPS devices (less than 1% of the total GPS devices are affected). The upper 10 MHz intended for use by LightSquared may have some effect on GPS devices. There is some concern that this may seriously degrade the GPS signal for many consumer uses.<a href="#cite_note-gpsworld-20110301-168">[167]</a><a href="#cite_note-169">[168]</a> <a href="/wiki/Aviation_Week" class="mw-redirect" title="Aviation Week">Aviation Week</a> magazine reports that the latest testing (June 2011) confirms "significant jamming" of GPS by LightSquared's system.<a href="#cite_note-aviationweek1-170">[169]</a> <div class="mw-heading mw-heading3"><h3 id="Demodulation_and_decoding">Demodulation and decoding</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=28" title="Edit section: Demodulation and decoding">edit</a>]</div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Gps_ca_gold.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Gps_ca_gold.svg/180px-Gps_ca_gold.svg.png" decoding="async" width="180" height="106" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Gps_ca_gold.svg/270px-Gps_ca_gold.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Gps_ca_gold.svg/360px-Gps_ca_gold.svg.png 2x" data-file-width="864" data-file-height="509" /></a><figcaption>Demodulating and Decoding GPS Satellite Signals using the Coarse/Acquisition <a href="/wiki/Gold_code" title="Gold code">Gold code</a></figcaption></figure> Because all of the satellite signals are modulated onto the same L1 carrier frequency, the signals must be separated after demodulation. This is done by assigning each satellite a unique binary <a href="/wiki/Sequence" title="Sequence">sequence</a> known as a <a href="/wiki/Gold_code" title="Gold code">Gold code</a>. The signals are decoded after demodulation using addition of the Gold codes corresponding to the satellites monitored by the receiver.<a href="#cite_note-171">[170]</a><a href="#cite_note-172">[171]</a> If the almanac information has previously been acquired, the receiver picks the satellites to listen for by their PRNs, unique numbers in the range 1 through 32. If the almanac information is not in memory, the receiver enters a search mode until a lock is obtained on one of the satellites. To obtain a lock, it is necessary that there be an unobstructed line of sight from the receiver to the satellite. The receiver can then acquire the almanac and determine the satellites it should listen for. As it detects each satellite's signal, it identifies it by its distinct C/A code pattern. There can be a delay of up to 30 seconds before the first estimate of position because of the need to read the ephemeris data. Processing of the navigation message enables the determination of the time of transmission and the satellite position at this time. For more information see <a href="/wiki/GPS_signals#Demodulation_and_decoding" title="GPS signals">Demodulation and Decoding, Advanced</a>. <div class="mw-heading mw-heading2"><h2 id="Navigation_equations">Navigation equations</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=29" title="Edit section: Navigation equations">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/GNSS_positioning_calculation" class="mw-redirect" title="GNSS positioning calculation">GNSS positioning calculation</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Pseudorange" title="Pseudorange">Pseudorange</a></div> <div class="mw-heading mw-heading3"><h3 id="Problem_statement">Problem statement</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=30" title="Edit section: Problem statement">edit</a>]</div> The receiver uses messages received from satellites to determine the satellite positions and time sent. The x, y, and z components of satellite position and the time sent (s) are designated as [xi, yi, zi, si] where the subscript i denotes the satellite and has the value 1, 2, ..., n, where n ≥ 4. When the time of message reception indicated by the on-board receiver clock is <math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\tilde {t}}_{i}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>t</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\tilde {t}}_{i}}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3759a4a95e6e6d46c16a1524f251cfe79ee0883e" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.156ex; height:2.843ex;" alt="{\displaystyle {\tilde {t}}_{i}}">, the true reception time is <math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle t_{i}={\tilde {t}}_{i}-b}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>t</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>=</mo> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>t</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>−</mo> <mi>b</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle t_{i}={\tilde {t}}_{i}-b}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/fa085b6829a739bca6591ec06d8a418d26f43e8d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:10.731ex; height:2.843ex;" alt="{\displaystyle t_{i}={\tilde {t}}_{i}-b}">, where b is the receiver's clock bias from the much more accurate GPS clocks employed by the satellites. The receiver clock bias is the same for all received satellite signals (assuming the satellite clocks are all perfectly synchronized). The message's transit time is <math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\tilde {t}}_{i}-b-s_{i}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>t</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>−</mo> <mi>b</mi> <mo>−</mo> <msub> <mi>s</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\tilde {t}}_{i}-b-s_{i}}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2630e047595ff58dfc10fe920181999cce7aa8fd" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:10.724ex; height:2.843ex;" alt="{\displaystyle {\tilde {t}}_{i}-b-s_{i}}">, where si is the satellite time. Assuming the message traveled at <a href="/wiki/Speed_of_light" title="Speed of light">the speed of light</a>, c, the distance traveled is <math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \left({\tilde {t}}_{i}-b-s_{i}\right)c}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow> <mo>(</mo> <mrow> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>t</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>−</mo> <mi>b</mi> <mo>−</mo> <msub> <mi>s</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> </mrow> <mo>)</mo> </mrow> <mi>c</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \left({\tilde {t}}_{i}-b-s_{i}\right)c}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/99fe3ae022fbe3910ce1d67cac8cef73a42c2684" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:14.248ex; height:3.176ex;" alt="{\displaystyle \left({\tilde {t}}_{i}-b-s_{i}\right)c}">. For n satellites, the equations to satisfy are: <dl><dd><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d_{i}=\left({\tilde {t}}_{i}-b-s_{i}\right)c,\;i=1,2,\dots ,n}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>=</mo> <mrow> <mo>(</mo> <mrow> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>t</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>−</mo> <mi>b</mi> <mo>−</mo> <msub> <mi>s</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> </mrow> <mo>)</mo> </mrow> <mi>c</mi> <mo>,</mo> <mspace width="thickmathspace" /> <mi>i</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>…</mo> <mo>,</mo> <mi>n</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d_{i}=\left({\tilde {t}}_{i}-b-s_{i}\right)c,\;i=1,2,\dots ,n}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c07ac0937c46847641597bfd9b61b7ecff0e2433" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:34.867ex; height:3.176ex;" alt="{\displaystyle d_{i}=\left({\tilde {t}}_{i}-b-s_{i}\right)c,\;i=1,2,\dots ,n}"></dd></dl> where di is the geometric distance or range between receiver and satellite i (the values without subscripts are the x, y, and z components of receiver position): <dl><dd><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d_{i}={\sqrt {(x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <msqrt> <mo stretchy="false">(</mo> <mi>x</mi> <mo>−</mo> <msub> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <msup> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>+</mo> <mo stretchy="false">(</mo> <mi>y</mi> <mo>−</mo> <msub> <mi>y</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <msup> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>+</mo> <mo stretchy="false">(</mo> <mi>z</mi> <mo>−</mo> <msub> <mi>z</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <msup> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> </msqrt> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d_{i}={\sqrt {(x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}}}}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/66ef03e69e884434ad6c9b4f09a8aaa10e9ef2de" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.671ex; width:39.746ex; height:4.843ex;" alt="{\displaystyle d_{i}={\sqrt {(x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}}}}"></dd></dl> Defining pseudoranges as <math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p_{i}=\left({\tilde {t}}_{i}-s_{i}\right)c}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>=</mo> <mrow> <mo>(</mo> <mrow> <msub> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>t</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>−</mo> <msub> <mi>s</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> </mrow> <mo>)</mo> </mrow> <mi>c</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle p_{i}=\left({\tilde {t}}_{i}-s_{i}\right)c}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/26a618ccc763920325a1ed0655c5213860c4a75e" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; margin-left: -0.089ex; width:15.567ex; height:3.176ex;" alt="{\displaystyle p_{i}=\left({\tilde {t}}_{i}-s_{i}\right)c}">, we see they are biased versions of the true range: <dl><dd><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p_{i}=d_{i}+bc,\;i=1,2,...,n}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <mo>+</mo> <mi>b</mi> <mi>c</mi> <mo>,</mo> <mspace width="thickmathspace" /> <mi>i</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <mi>n</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle p_{i}=d_{i}+bc,\;i=1,2,...,n}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c39cfec77473b8bf15040ac568e05acb5dabf621" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; margin-left: -0.089ex; width:27.514ex; height:2.509ex;" alt="{\displaystyle p_{i}=d_{i}+bc,\;i=1,2,...,n}"> .<a href="#cite_note-GPS_BASICS_Blewitt-173">[172]</a><a href="#cite_note-Bancroft-174">[173]</a></dd></dl> Since the equations have four unknowns [x, y, z, b]—the three components of GPS receiver position and the clock bias—signals from at least four satellites are necessary to attempt solving these equations. They can be solved by algebraic or numerical methods. Existence and uniqueness of GPS solutions are discussed by Abell and Chaffee.<a href="#cite_note-Abel1-75">[75]</a> When n is greater than four, this system is <a href="/wiki/Overdetermined_system" title="Overdetermined system">overdetermined</a> and a <a href="/wiki/Mean" title="Mean">fitting method</a> must be used. The amount of error in the results varies with the received satellites' locations in the sky, since certain configurations (when the received satellites are close together in the sky) cause larger errors. Receivers usually calculate a running estimate of the error in the calculated position. This is done by multiplying the basic resolution of the receiver by quantities called the <a href="/wiki/Dilution_of_precision_(navigation)" title="Dilution of precision (navigation)">geometric dilution of position</a> (GDOP) factors, calculated from the relative sky directions of the satellites used.<a href="#cite_note-175">[174]</a> The receiver location is expressed in a specific coordinate system, such as latitude and longitude using the <a href="/wiki/WGS_84" class="mw-redirect" title="WGS 84">WGS 84</a> <a href="/wiki/Datum_(geodesy)" class="mw-redirect" title="Datum (geodesy)">geodetic datum</a> or a country-specific system.<a href="#cite_note-176">[175]</a> <div class="mw-heading mw-heading3"><h3 id="Geometric_interpretation">Geometric interpretation</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=31" title="Edit section: Geometric interpretation">edit</a>]</div> The GPS equations can be solved by numerical and analytical methods. Geometrical interpretations can enhance the understanding of these solution methods. <div class="mw-heading mw-heading4"><h4 id="Spheres">Spheres</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=32" title="Edit section: Spheres">edit</a>]</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:2D_Trilat_Scenario_2019-0116.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/83/2D_Trilat_Scenario_2019-0116.jpg/220px-2D_Trilat_Scenario_2019-0116.jpg" decoding="async" width="220" height="219" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/83/2D_Trilat_Scenario_2019-0116.jpg/330px-2D_Trilat_Scenario_2019-0116.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/83/2D_Trilat_Scenario_2019-0116.jpg/440px-2D_Trilat_Scenario_2019-0116.jpg 2x" data-file-width="487" data-file-height="484" /></a><figcaption>2-D Cartesian true-range multilateration (trilateration) scenario</figcaption></figure> The measured ranges, called pseudoranges, contain clock errors. In a simplified idealization in which the ranges are synchronized, these true ranges represent the radii of spheres, each centered on one of the transmitting satellites. The solution for the position of the receiver is then at the intersection of the surfaces of these spheres; see <a href="/wiki/Trilateration" title="Trilateration">trilateration</a> (more generally, true-range multilateration). Signals from at minimum three satellites are required, and their three spheres would typically intersect at two points.<a href="#cite_note-177">[176]</a> One of the points is the location of the receiver, and the other moves rapidly in successive measurements and would not usually be on Earth's surface. In practice, there are many sources of inaccuracy besides clock bias, including random errors as well as the potential for precision loss from subtracting numbers close to each other if the centers of the spheres are relatively close together. This means that the position calculated from three satellites alone is unlikely to be accurate enough. Data from more satellites can help because of the tendency for random errors to cancel out and also by giving a larger spread between the sphere centers. But at the same time, more spheres will not generally intersect at one point. Therefore, a near intersection gets computed, typically via least squares. The more signals available, the better the approximation is likely to be. <div class="mw-heading mw-heading4"><h4 id="Hyperboloids">Hyperboloids</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=33" title="Edit section: Hyperboloids">edit</a>]</div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Hyperbolic_Navigation.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/91/Hyperbolic_Navigation.svg/219px-Hyperbolic_Navigation.svg.png" decoding="async" width="219" height="139" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/91/Hyperbolic_Navigation.svg/329px-Hyperbolic_Navigation.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/91/Hyperbolic_Navigation.svg/438px-Hyperbolic_Navigation.svg.png 2x" data-file-width="842" data-file-height="535" /></a><figcaption>Three satellites (labeled as "stations" A, B, C) have known locations. The true times it takes for a radio signal to travel from each satellite to the receiver are unknown, but the true time differences are known. Then, each time difference locates the receiver on a branch of a hyperbola focused on the satellites. The receiver is then located at one of the two intersections.</figcaption></figure> If the pseudorange between the receiver and satellite i and the pseudorange between the receiver and satellite j are subtracted, pi − pj, the common receiver clock bias (b) cancels out, resulting in a difference of distances di − dj. The locus of points having a constant difference in distance to two points (here, two satellites) is a <a href="/wiki/Hyperbola" title="Hyperbola">hyperbola</a> on a plane and a <a href="/wiki/Hyperboloid_of_revolution" class="mw-redirect" title="Hyperboloid of revolution">hyperboloid of revolution</a> (more specifically, a <a href="/wiki/Two-sheeted_hyperboloid" class="mw-redirect" title="Two-sheeted hyperboloid">two-sheeted hyperboloid</a>) in 3D space (see <a href="/wiki/Multilateration" class="mw-redirect" title="Multilateration">Multilateration</a>). Thus, from four pseudorange measurements, the receiver can be placed at the intersection of the surfaces of three hyperboloids each with <a href="/wiki/Focus_(geometry)" title="Focus (geometry)">foci</a> at a pair of satellites. With additional satellites, the multiple intersections are not necessarily unique, and a best-fitting solution is sought instead.<a href="#cite_note-Abel1-75">[75]</a><a href="#cite_note-Fang-76">[76]</a><a href="#cite_note-178">[177]</a><a href="#cite_note-179">[178]</a><a href="#cite_note-HWLW-180">[179]</a><a href="#cite_note-Groves2013-181">[180]</a> <div class="mw-heading mw-heading4"><h4 id="Inscribed_sphere">Inscribed sphere</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=34" title="Edit section: Inscribed sphere">edit</a>]</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Descartes_Circles.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Descartes_Circles.svg/220px-Descartes_Circles.svg.png" decoding="async" width="220" height="220" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/87/Descartes_Circles.svg/330px-Descartes_Circles.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/87/Descartes_Circles.svg/440px-Descartes_Circles.svg.png 2x" data-file-width="500" data-file-height="500" /></a><figcaption>A smaller circle (<style data-mw-deduplicate="TemplateStyles:r1239334494">@media screen{html.skin-theme-clientpref-night .mw-parser-output div:not(.notheme)>.tmp-color,html.skin-theme-clientpref-night .mw-parser-output p>.tmp-color,html.skin-theme-clientpref-night .mw-parser-output table:not(.notheme) .tmp-color{color:inherit!important}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output div:not(.notheme)>.tmp-color,html.skin-theme-clientpref-os .mw-parser-output p>.tmp-color,html.skin-theme-clientpref-os .mw-parser-output table:not(.notheme) .tmp-color{color:inherit!important}}</style>red) inscribed and tangent to other circles (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494">black), that need not necessarily be mutually tangent</figcaption></figure> The receiver position can be interpreted as the center of an <a href="/wiki/Inscribed_sphere" title="Inscribed sphere">inscribed sphere</a> (insphere) of radius bc, given by the receiver clock bias b (scaled by the speed of light c). The insphere location is such that it touches other spheres. The <a href="/wiki/Circumscribed_sphere" title="Circumscribed sphere">circumscribing spheres</a> are centered at the GPS satellites, whose radii equal the measured pseudoranges pi. This configuration is distinct from the one described above, in which the spheres' radii were the unbiased or geometric ranges di.<a href="#cite_note-HWLW-180">[179]</a>: 36–37 <a href="#cite_note-Hoshen_1996-182">[181]</a> <div class="mw-heading mw-heading4"><h4 id="Hypercones">Hypercones</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=35" title="Edit section: Hypercones">edit</a>]</div> The clock in the receiver is usually not of the same quality as the ones in the satellites and will not be accurately synchronized to them. This produces <a href="/wiki/Pseudorange" title="Pseudorange">pseudoranges</a> with large differences compared to the true distances to the satellites. Therefore, in practice, the time difference between the receiver clock and the satellite time is defined as an unknown clock bias b. The equations are then solved simultaneously for the receiver position and the clock bias. The solution space [x, y, z, b] can be seen as a four-dimensional <a href="/wiki/Spacetime" title="Spacetime">spacetime</a>, and signals from at minimum four satellites are needed. In that case each of the equations describes a <a href="/wiki/Hypercone" title="Hypercone">hypercone</a> (or spherical cone),<a href="#cite_note-183">[182]</a> with the cusp located at the satellite, and the base a sphere around the satellite. The receiver is at the intersection of four or more of such hypercones. <div class="mw-heading mw-heading3"><h3 id="Solution_methods">Solution methods</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=36" title="Edit section: Solution methods">edit</a>]</div> <div class="mw-heading mw-heading4"><h4 id="Least_squares">Least squares</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=37" title="Edit section: Least squares">edit</a>]</div> When more than four satellites are available, the calculation can use the four best, or more than four simultaneously (up to all visible satellites), depending on the number of receiver channels, processing capability, and <a href="/wiki/Dilution_of_precision_(GPS)" class="mw-redirect" title="Dilution of precision (GPS)">geometric dilution of precision</a> (GDOP). Using more than four involves an over-determined system of equations with no unique solution; such a system can be solved by a <a href="/wiki/Least-squares" class="mw-redirect" title="Least-squares">least-squares</a> or weighted least squares method.<a href="#cite_note-GPS_BASICS_Blewitt-173">[172]</a> <dl><dd><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \left({\hat {x}},{\hat {y}},{\hat {z}},{\hat {b}}\right)={\underset {\left(x,y,z,b\right)}{\arg \min }}\sum _{i}\left({\sqrt {(x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}}}+bc-p_{i}\right)^{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow> <mo>(</mo> <mrow> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>x</mi> <mo stretchy="false">^</mo> </mover> </mrow> </mrow> <mo>,</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>y</mi> <mo stretchy="false">^</mo> </mover> </mrow> </mrow> <mo>,</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>z</mi> <mo stretchy="false">^</mo> </mover> </mrow> </mrow> <mo>,</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>b</mi> <mo stretchy="false">^</mo> </mover> </mrow> </mrow> </mrow> <mo>)</mo> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <munder> <mrow> <mi>arg</mi> <mo>⁡</mo> <mo movablelimits="true" form="prefix">min</mo> </mrow> <mrow> <mo>(</mo> <mrow> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>,</mo> <mi>z</mi> <mo>,</mo> <mi>b</mi> </mrow> <mo>)</mo> </mrow> </munder> </mrow> <munder> <mo>∑</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </munder> <msup> <mrow> <mo>(</mo> <mrow> <mrow class="MJX-TeXAtom-ORD"> <msqrt> <mo stretchy="false">(</mo> <mi>x</mi> <mo>−</mo> <msub> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <msup> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>+</mo> <mo stretchy="false">(</mo> <mi>y</mi> <mo>−</mo> <msub> <mi>y</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <msup> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>+</mo> <mo stretchy="false">(</mo> <mi>z</mi> <mo>−</mo> <msub> <mi>z</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> <msup> <mo stretchy="false">)</mo> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> </msqrt> </mrow> <mo>+</mo> <mi>b</mi> <mi>c</mi> <mo>−</mo> <msub> <mi>p</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> </mrow> </msub> </mrow> <mo>)</mo> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \left({\hat {x}},{\hat {y}},{\hat {z}},{\hat {b}}\right)={\underset {\left(x,y,z,b\right)}{\arg \min }}\sum _{i}\left({\sqrt {(x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}}}+bc-p_{i}\right)^{2}}</annotation> </semantics> </math><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/df60672369a19718618540d64bbb21923971ab30" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.005ex; width:73.817ex; height:6.676ex;" alt="{\displaystyle \left({\hat {x}},{\hat {y}},{\hat {z}},{\hat {b}}\right)={\underset {\left(x,y,z,b\right)}{\arg \min }}\sum _{i}\left({\sqrt {(x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}}}+bc-p_{i}\right)^{2}}"></dd></dl> <div class="mw-heading mw-heading4"><h4 id="Iterative">Iterative</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=38" title="Edit section: Iterative">edit</a>]</div> Both the equations for four satellites, or the least squares equations for more than four, are non-linear and need special solution methods. A common approach is by iteration on a linearized form of the equations, such as the <a href="/wiki/Gauss%E2%80%93Newton_algorithm" title="Gauss–Newton algorithm">Gauss–Newton algorithm</a>. The GPS was initially developed assuming use of a numerical least-squares solution method—i.e., before closed-form solutions were found. <div class="mw-heading mw-heading4"><h4 id="Closed-form">Closed-form</h4>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=39" title="Edit section: Closed-form">edit</a>]</div> One closed-form solution to the above set of equations was developed by S. Bancroft.<a href="#cite_note-Bancroft-174">[173]</a><a href="#cite_note-Bancroft1985-184">[183]</a> Its properties are well known;<a href="#cite_note-Abel1-75">[75]</a><a href="#cite_note-Fang-76">[76]</a><a href="#cite_note-Chaffee-185">[184]</a> in particular, proponents claim it is superior in low-<a href="/wiki/Geometric_dilution_of_precision" class="mw-redirect" title="Geometric dilution of precision">GDOP</a> situations, compared to iterative least squares methods.<a href="#cite_note-Bancroft1985-184">[183]</a> Bancroft's method is algebraic, as opposed to numerical, and can be used for four or more satellites. When four satellites are used, the key steps are inversion of a 4x4 matrix and solution of a single-variable quadratic equation. Bancroft's method provides one or two solutions for the unknown quantities. When there are two (usually the case), only one is a near-Earth sensible solution.<a href="#cite_note-Bancroft-174">[173]</a> When a receiver uses more than four satellites for a solution, Bancroft uses the <a href="/wiki/Generalized_inverse" title="Generalized inverse">generalized inverse</a> (i.e., the pseudoinverse) to find a solution. A case has been made that iterative methods, such as the Gauss–Newton algorithm approach for solving over-determined <a href="/wiki/Non-linear_least_squares" title="Non-linear least squares">non-linear least squares</a> problems, generally provide more accurate solutions.<a href="#cite_note-Sirola2010-186">[185]</a> Leick et al. (2015) states that "Bancroft's (1985) solution is a very early, if not the first, closed-form solution."<a href="#cite_note-187">[186]</a> Other closed-form solutions were published afterwards,<a href="#cite_note-Kleus-188">[187]</a><a href="#cite_note-Oszczak-189">[188]</a> although their adoption in practice is unclear. <div class="mw-heading mw-heading3"><h3 id="Error_sources_and_analysis">Error sources and analysis</h3>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=40" title="Edit section: Error sources and analysis">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Error_analysis_for_the_Global_Positioning_System" title="Error analysis for the Global Positioning System">Error analysis for the Global Positioning System</a></div> GPS error analysis examines error sources in GPS results and the expected size of those errors. GPS makes corrections for receiver clock errors and other effects, but some residual errors remain uncorrected. Error sources include signal arrival time measurements, numerical calculations, atmospheric effects (ionospheric/tropospheric delays), <a href="/wiki/Ephemeris" title="Ephemeris">ephemeris</a> and clock data, multipath signals, and natural and artificial interference. Magnitude of residual errors from these sources depends on geometric dilution of precision. Artificial errors may result from jamming devices and threaten ships and aircraft<a href="#cite_note-190">[189]</a> or from intentional signal degradation through selective availability, which limited accuracy to ≈ 6–12 m (20–40 ft), but has been switched off since May 1, 2000.<a href="#cite_note-191">[190]</a><a href="#cite_note-192">[191]</a> <div class="mw-heading mw-heading2"><h2 id="Accuracy_enhancement_and_surveying">Accuracy enhancement and surveying</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=41" title="Edit section: Accuracy enhancement and surveying">edit</a>]</div> <div class="excerpt-block"><style data-mw-deduplicate="TemplateStyles:r1066933788">.mw-parser-output .excerpt-hat .mw-editsection-like{font-style:normal}</style><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable dablink excerpt-hat selfref">This section is an excerpt from <a href="/wiki/GNSS_enhancement" title="GNSS enhancement">GNSS enhancement</a>.[<a class="external text" href="https://en.wikipedia.org/w/index.php?title=GNSS_enhancement&action=edit">edit</a>]</div><div class="excerpt"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-Expert_needed plainlinks metadata ambox ambox-content" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/40px-Ambox_important.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/60px-Ambox_important.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/80px-Ambox_important.svg.png 2x" data-file-width="40" data-file-height="40" /></div></td><td class="mbox-text"><div class="mbox-text-span">This article needs attention from an expert in Geography. The specific problem is: possibly duplicate references to the same phase stuff, esp. between RTK and carrier-phase tracking. <a href="/wiki/Wikipedia:WikiProject_Geography" title="Wikipedia:WikiProject Geography">WikiProject Geography</a> may be able to help recruit an expert. (March 2020)</div></td></tr></tbody></table> <a href="/wiki/GNSS_enhancement" title="GNSS enhancement">GNSS enhancement</a> refers to techniques used to improve the accuracy of positioning information provided by the Global Positioning System or other <a href="/wiki/Global_navigation_satellite_systems" class="mw-redirect" title="Global navigation satellite systems">global navigation satellite systems</a> in general, a network of satellites used for navigation. Enhancement methods of improving accuracy rely on external information being integrated into the calculation process. There are many such systems in place and they are generally named or described based on how the GPS sensor receives the information. Some systems transmit additional information about sources of error (such as clock drift, ephemeris, or <a href="/wiki/Ionospheric_delay" class="mw-redirect" title="Ionospheric delay">ionospheric delay</a>), others provide direct measurements of how much the signal was off in the past, while a third group provides additional navigational or vehicle information to be integrated into the calculation process.</div></div> <div class="mw-heading mw-heading2"><h2 id="Regulatory_spectrum_issues_concerning_GPS_receivers">Regulatory spectrum issues concerning GPS receivers</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=42" title="Edit section: Regulatory spectrum issues concerning GPS receivers">edit</a>]</div> In the United States, GPS receivers are regulated under the <a href="/wiki/Federal_Communications_Commission" title="Federal Communications Commission">Federal Communications Commission</a>'s (FCC) <a href="/wiki/Title_47_CFR_Part_15" title="Title 47 CFR Part 15">Part 15</a> rules. As indicated in the manuals of GPS-enabled devices sold in the United States, as a Part 15 device, it "must accept any interference received, including interference that may cause undesired operation".<a href="#cite_note-193">[192]</a> With respect to GPS devices in particular, the FCC states that GPS receiver manufacturers "must use receivers that reasonably discriminate against reception of signals outside their allocated spectrum".<a href="#cite_note-FCC.gov-194">[193]</a> For the last 30 years, GPS receivers have operated next to the Mobile Satellite Service band, and have discriminated against reception of mobile satellite services, such as Inmarsat, without any issue. The spectrum allocated for GPS L1 use by the FCC is 1559 to 1610 MHz, while the spectrum allocated for satellite-to-ground use owned by Lightsquared is the Mobile Satellite Service band.<a href="#cite_note-195">[194]</a> Since 1996, the FCC has authorized licensed use of the spectrum neighboring the GPS band of 1525 to 1559 MHz to the <a href="/wiki/Virginia" title="Virginia">Virginia</a> company <a href="/wiki/LightSquared" class="mw-redirect" title="LightSquared">LightSquared</a>. On March 1, 2001, the FCC received an application from LightSquared's predecessor, <a href="/wiki/Motient" class="mw-redirect" title="Motient">Motient</a> Services, to use their allocated frequencies for an integrated satellite-terrestrial service.<a href="#cite_note-FCC-196">[195]</a> In 2002, the U.S. GPS Industry Council came to an out-of-band-emissions (OOBE) agreement with LightSquared to prevent transmissions from LightSquared's ground-based stations from emitting transmissions into the neighboring GPS band of 1559 to 1610 MHz.<a href="#cite_note-197">[196]</a> In 2004, the FCC adopted the OOBE agreement in its authorization for LightSquared to deploy a ground-based network ancillary to their satellite system – known as the Ancillary Tower Components (ATCs) – "We will authorize MSS ATC subject to conditions that ensure that the added terrestrial component remains ancillary to the principal MSS offering. We do not intend, nor will we permit, the terrestrial component to become a stand-alone service."<a href="#cite_note-hraunfoss.fcc.gov-198">[197]</a> This authorization was reviewed and approved by the U.S. Interdepartment Radio Advisory Committee, which includes the <a href="/wiki/U.S._Department_of_Agriculture" class="mw-redirect" title="U.S. Department of Agriculture">U.S. Department of Agriculture</a>, U.S. Space Force, U.S. Army, <a href="/wiki/U.S._Coast_Guard" class="mw-redirect" title="U.S. Coast Guard">U.S. Coast Guard</a>, <a href="/wiki/Federal_Aviation_Administration" title="Federal Aviation Administration">Federal Aviation Administration</a>, <a href="/wiki/National_Aeronautics_and_Space_Administration" class="mw-redirect" title="National Aeronautics and Space Administration">National Aeronautics and Space Administration</a> (NASA), <a href="/wiki/United_States_Department_of_the_Interior" title="United States Department of the Interior">U.S. Department of the Interior</a>, and <a href="/wiki/U.S._Department_of_Transportation" class="mw-redirect" title="U.S. Department of Transportation">U.S. Department of Transportation</a>.<a href="#cite_note-199">[198]</a> In January 2011, the FCC conditionally authorized LightSquared's wholesale customers—such as <a href="/wiki/Best_Buy" title="Best Buy">Best Buy</a>, <a href="/wiki/Sharp_Corporation" title="Sharp Corporation">Sharp</a>, and <a href="/wiki/C_Spire" title="C Spire">C Spire</a>—to only purchase an integrated satellite-ground-based service from LightSquared and re-sell that integrated service on devices that are equipped to only use the ground-based signal using LightSquared's allocated frequencies of 1525 to 1559 MHz.<a href="#cite_note-200">[199]</a> In December 2010, GPS receiver manufacturers expressed concerns to the FCC that LightSquared's signal would interfere with GPS receiver devices<a href="#cite_note-gpsworld-20110301-168">[167]</a> although the FCC's policy considerations leading up to the January 2011 order did not pertain to any proposed changes to the maximum number of ground-based LightSquared stations or the maximum power at which these stations could operate. The January 2011 order makes final authorization contingent upon studies of GPS interference issues carried out by a LightSquared led working group along with GPS industry and Federal agency participation. On February 14, 2012, the FCC initiated proceedings to vacate LightSquared's Conditional Waiver Order based on the NTIA's conclusion that there was currently no practical way to mitigate potential GPS interference. GPS receiver manufacturers design GPS receivers to use spectrum beyond the GPS-allocated band. In some cases, GPS receivers are designed to use up to 400 MHz of spectrum in either direction of the L1 frequency of 1575.42 MHz, because mobile satellite services in those regions are broadcasting from space to ground, and at power levels commensurate with mobile satellite services.<a href="#cite_note-201">[200]</a> As regulated under the FCC's Part 15 rules, GPS receivers are not warranted protection from signals outside GPS-allocated spectrum.<a href="#cite_note-FCC.gov-194">[193]</a> This is why GPS operates next to the Mobile Satellite Service band, and also why the Mobile Satellite Service band operates next to GPS. The symbiotic relationship of spectrum allocation ensures that users of both bands are able to operate cooperatively and freely. The FCC adopted rules in February 2003 that allowed Mobile Satellite Service (MSS) licensees such as LightSquared to construct a small number of ancillary ground-based towers in their licensed spectrum to "promote more efficient use of terrestrial wireless spectrum".<a href="#cite_note-202">[201]</a> In those 2003 rules, the FCC stated: "As a preliminary matter, terrestrial [Commercial Mobile Radio Service ('CMRS')] and MSS ATC are expected to have different prices, coverage, product acceptance and distribution; therefore, the two services appear, at best, to be imperfect substitutes for one another that would be operating in predominantly different market segments ... MSS ATC is unlikely to compete directly with terrestrial CMRS for the same customer base...". In 2004, the FCC clarified that the ground-based towers would be ancillary, noting: "We will authorize MSS ATC subject to conditions that ensure that the added terrestrial component remains ancillary to the principal MSS offering. We do not intend, nor will we permit, the terrestrial component to become a stand-alone service."<a href="#cite_note-hraunfoss.fcc.gov-198">[197]</a> In July 2010, the FCC stated that it expected LightSquared to use its authority to offer an integrated satellite-terrestrial service to "provide mobile broadband services similar to those provided by terrestrial mobile providers and enhance competition in the mobile broadband sector".<a href="#cite_note-203">[202]</a> GPS receiver manufacturers have argued that LightSquared's licensed spectrum of 1525 to 1559 MHz was never envisioned as being used for high-speed wireless broadband based on the 2003 and 2004 FCC ATC rulings making clear that the Ancillary Tower Component (ATC) would be, in fact, ancillary to the primary satellite component.<a href="#cite_note-LightSquared_DOD_GPS_Spec-204">[203]</a> To build public support of efforts to continue the 2004 FCC authorization of LightSquared's ancillary terrestrial component vs. a simple ground-based LTE service in the Mobile Satellite Service band, GPS receiver manufacturer <a href="/wiki/Trimble_Navigation" class="mw-redirect" title="Trimble Navigation">Trimble Navigation</a> Ltd. formed the "Coalition To Save Our GPS".<a href="#cite_note-Coalition_To_Save_Our_GPS-205">[204]</a> The FCC and LightSquared have each made public commitments to solve the GPS interference issue before the network is allowed to operate.<a href="#cite_note-206">[205]</a><a href="#cite_note-207">[206]</a> According to Chris Dancy of the <a href="/wiki/Aircraft_Owners_and_Pilots_Association" title="Aircraft Owners and Pilots Association">Aircraft Owners and Pilots Association</a>, airline pilots with the type of systems that would be affected "may go off course and not even realize it".<a href="#cite_note-Tessler-208">[207]</a> The problems could also affect the Federal Aviation Administration upgrade to the <a href="/wiki/Air_traffic_control" title="Air traffic control">air traffic control</a> system, <a href="/wiki/United_States_Defense_Department" class="mw-redirect" title="United States Defense Department">United States Defense Department</a> guidance, and local <a href="/wiki/Emergency_service" title="Emergency service">emergency services</a> including <a href="/wiki/9-1-1" class="mw-redirect" title="9-1-1">911</a>.<a href="#cite_note-Tessler-208">[207]</a> On February 14, 2012, the FCC moved to bar LightSquared's planned national broadband network after being informed by the <a href="/wiki/National_Telecommunications_and_Information_Administration" title="National Telecommunications and Information Administration">National Telecommunications and Information Administration</a> (NTIA), the federal agency that coordinates spectrum uses for the military and other federal government entities, that "there is no practical way to mitigate potential interference at this time".<a href="#cite_note-FCC20120214-209">[208]</a><a href="#cite_note-210">[209]</a> LightSquared is challenging the FCC's action.[<a href="/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items" title="Wikipedia:Manual of Style/Dates and numbers">needs update</a>] <div class="mw-heading mw-heading2"><h2 id="Similar_systems">Similar systems</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=43" title="Edit section: Similar systems">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Satellite_navigation" title="Satellite navigation">Satellite navigation</a></div> <figure typeof="mw:File/Thumb"><a href="//upload.wikimedia.org/wikipedia/commons/b/b4/Comparison_satellite_navigation_orbits.svg"><img resource="/wiki/File:Comparison_satellite_navigation_orbits.svg" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Comparison_satellite_navigation_orbits.svg/250px-Comparison_satellite_navigation_orbits.svg.png" decoding="async" width="250" height="250" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Comparison_satellite_navigation_orbits.svg/375px-Comparison_satellite_navigation_orbits.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Comparison_satellite_navigation_orbits.svg/500px-Comparison_satellite_navigation_orbits.svg.png 2x" data-file-width="512" data-file-height="512" /></a><figcaption>Clickable image, highlighting <a href="/wiki/Medium_Earth_Orbit" class="mw-redirect" title="Medium Earth Orbit">medium altitude orbits around Earth</a>,<a href="#cite_note-211">[b]</a> from <a href="/wiki/Low_Earth_orbit" title="Low Earth orbit">Low Earth</a> to the lowest <a href="/wiki/High_Earth_orbit" title="High Earth orbit">High Earth orbit</a> (<a href="/wiki/Geostationary_Earth_orbit" class="mw-redirect" title="Geostationary Earth orbit">geostationary orbit</a> and its <a href="/wiki/Graveyard_orbit" title="Graveyard orbit">graveyard orbit</a>, at one ninth of the <a href="/wiki/Lunar_distance" title="Lunar distance">Moon's orbital distance</a>),<a href="#cite_note-212">[c]</a> with the <a href="/wiki/Van_Allen_radiation_belt" title="Van Allen radiation belt">Van Allen radiation belts</a> and the <a href="/wiki/Earth" title="Earth">Earth</a> to scale</figcaption></figure> Following the United States' deployment of GPS, other countries have also developed their own satellite navigation systems. These systems include: <ul><li>The Russian Global Navigation Satellite System (<a href="/wiki/GLONASS" title="GLONASS">GLONASS</a>) was developed at the same time as GPS, but suffered from incomplete coverage of the globe until the mid-2000s.<a href="#cite_note-213">[210]</a> GLONASS reception in addition to GPS can be combined in a receiver thereby allowing for additional satellites available to enable faster position fixes and improved accuracy, to within two meters (6.6 ft).<a href="#cite_note-214">[211]</a><a href="#cite_note-215">[212]</a></li> <li>China's <a href="/wiki/BeiDou_Navigation_Satellite_System" class="mw-redirect" title="BeiDou Navigation Satellite System">BeiDou Navigation Satellite System</a> began global services in 2018 and finished its full deployment in 2020.<a href="#cite_note-216">[213]</a></li> <li>The <a href="/wiki/Galileo_(satellite_navigation)" title="Galileo (satellite navigation)">Galileo navigation satellite system</a>, a global system being developed by the <a href="/wiki/European_Union" title="European Union">European Union</a> and other partner countries, began operation in 2016,<a href="#cite_note-217">[214]</a> and is expected to be fully deployed by 2020.[<a href="/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items" title="Wikipedia:Manual of Style/Dates and numbers">needs update</a>]</li> <li>Japan's <a href="/wiki/Quasi-Zenith_Satellite_System" title="Quasi-Zenith Satellite System">Quasi-Zenith Satellite System</a> (QZSS) is a GPS <a href="/wiki/Satellite-based_augmentation_system" class="mw-redirect" title="Satellite-based augmentation system">satellite-based augmentation system</a> to enhance GPS's accuracy in Asia-Oceania, with satellite navigation independent of GPS scheduled for 2023.<a href="#cite_note-218">[215]</a></li> <li>The <a href="/wiki/Indian_Regional_Navigation_Satellite_System" title="Indian Regional Navigation Satellite System">Indian Regional Navigation Satellite System</a> (Operational name 'NavIC', Navigation with Indian Constellation), deployed by India.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Backup_system">Backup system</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=44" title="Edit section: Backup system">edit</a>]</div> In the event of adverse <a href="/wiki/Space_weather" title="Space weather">space weather</a> or the deployment of an anti-satellite weapon against GPS, the United States has no terrestrial backup system. The potential cost of such an event to the U.S. economy is estimated at $1 billion per day. The <a href="/wiki/LORAN-C" class="mw-redirect" title="LORAN-C">LORAN-C</a> system was turned off in North America in 2010 and Europe in 2015. <a href="/wiki/ELoran" title="ELoran">eLoran</a> is proposed as an American terrestrial backup system, but as of 2024 has not received approval or funding.<a href="#cite_note-219">[216]</a> China continues to operate LORAN-C transmitters,<a href="#cite_note-220">[217]</a> and Russia has a similar system called <a href="/wiki/CHAYKA" title="CHAYKA">CHAYKA</a> ("Seagull"). <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=45" title="Edit section: See also">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 15em;"> <ul><li><a href="/wiki/List_of_GPS_satellites" title="List of GPS satellites">List of GPS satellites</a></li> <li><a href="/wiki/GPS_satellite_blocks" title="GPS satellite blocks">GPS satellite blocks</a></li> <li><a href="/wiki/GPS_signals" title="GPS signals">GPS signals</a></li> <li><a href="/wiki/Satellite_navigation_software" title="Satellite navigation software">Satellite navigation software</a></li> <li><a href="/wiki/GPS/INS" title="GPS/INS">GPS/INS</a></li> <li><a href="/wiki/GPS_spoofing" class="mw-redirect" title="GPS spoofing">GPS spoofing</a></li> <li><a href="/wiki/Indoor_positioning_system" title="Indoor positioning system">Indoor positioning system</a></li> <li><a href="/wiki/Local-area_augmentation_system" title="Local-area augmentation system">Local-area augmentation system</a></li> <li><a href="/wiki/Local_positioning_system" class="mw-redirect" title="Local positioning system">Local positioning system</a></li> <li><a href="/wiki/Military_invention" class="mw-redirect" title="Military invention">Military invention</a></li> <li><a href="/wiki/Mobile_phone_tracking" title="Mobile phone tracking">Mobile phone tracking</a></li> <li><a href="/wiki/Navigation_paradox" title="Navigation paradox">Navigation paradox</a></li> <li><a href="/wiki/Notice_Advisory_to_Navstar_Users" title="Notice Advisory to Navstar Users">Notice Advisory to Navstar Users</a></li> <li><a href="/wiki/S-GPS" title="S-GPS">S-GPS</a></li> <li><a href="/wiki/High-altitude_balloon#Geostationary_balloon_satellite" title="High-altitude balloon">Geostationary balloon satellite</a></li></ul> </div> <style data-mw-deduplicate="TemplateStyles:r1130092004">.mw-parser-output .portal-bar{font-size:88%;font-weight:bold;display:flex;justify-content:center;align-items:baseline}.mw-parser-output .portal-bar-bordered{padding:0 2em;background-color:#fdfdfd;border:1px solid #a2a9b1;clear:both;margin:1em auto 0}.mw-parser-output .portal-bar-related{font-size:100%;justify-content:flex-start}.mw-parser-output .portal-bar-unbordered{padding:0 1.7em;margin-left:0}.mw-parser-output .portal-bar-header{margin:0 1em 0 0.5em;flex:0 0 auto;min-height:24px}.mw-parser-output .portal-bar-content{display:flex;flex-flow:row wrap;flex:0 1 auto;padding:0.15em 0;column-gap:1em;align-items:baseline;margin:0;list-style:none}.mw-parser-output .portal-bar-content-related{margin:0;list-style:none}.mw-parser-output .portal-bar-item{display:inline-block;margin:0.15em 0.2em;min-height:24px;line-height:24px}@media screen and (max-width:768px){.mw-parser-output .portal-bar{font-size:88%;font-weight:bold;display:flex;flex-flow:column wrap;align-items:baseline}.mw-parser-output .portal-bar-header{text-align:center;flex:0;padding-left:0.5em;margin:0 auto}.mw-parser-output .portal-bar-related{font-size:100%;align-items:flex-start}.mw-parser-output .portal-bar-content{display:flex;flex-flow:row wrap;align-items:center;flex:0;column-gap:1em;border-top:1px solid #a2a9b1;margin:0 auto;list-style:none}.mw-parser-output .portal-bar-content-related{border-top:none;margin:0;list-style:none}}.mw-parser-output .navbox+link+.portal-bar,.mw-parser-output .navbox+style+.portal-bar,.mw-parser-output .navbox+link+.portal-bar-bordered,.mw-parser-output .navbox+style+.portal-bar-bordered,.mw-parser-output .sister-bar+link+.portal-bar,.mw-parser-output .sister-bar+style+.portal-bar,.mw-parser-output .portal-bar+.navbox-styles+.navbox,.mw-parser-output .portal-bar+.navbox-styles+.sister-bar{margin-top:-1px}</style><div class="portal-bar noprint metadata noviewer portal-bar-bordered" role="navigation" aria-label="Portals"><a href="/wiki/Wikipedia:Contents/Portals" title="Wikipedia:Contents/Portals">Portals</a>:<ul class="portal-bar-content"><li class="portal-bar-item"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/RocketSunIcon.svg/19px-RocketSunIcon.svg.png" decoding="async" width="19" height="19" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/RocketSunIcon.svg/29px-RocketSunIcon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d6/RocketSunIcon.svg/38px-RocketSunIcon.svg.png 2x" data-file-width="128" data-file-height="128" /> <a href="/wiki/Portal:Spaceflight" title="Portal:Spaceflight">Spaceflight</a></li><li class="portal-bar-item"><img alt="icon" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Terra.png/19px-Terra.png" decoding="async" width="19" height="19" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Terra.png/29px-Terra.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Terra.png/38px-Terra.png 2x" data-file-width="600" data-file-height="600" /> <a href="/wiki/Portal:Geography" title="Portal:Geography">Geography</a></li><li class="portal-bar-item"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Worldmap_LandAndPolitical.jpg/21px-Worldmap_LandAndPolitical.jpg" decoding="async" width="21" height="11" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Worldmap_LandAndPolitical.jpg/32px-Worldmap_LandAndPolitical.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cf/Worldmap_LandAndPolitical.jpg/42px-Worldmap_LandAndPolitical.jpg 2x" data-file-width="5712" data-file-height="2986" /> <a href="/wiki/Portal:Maps" title="Portal:Maps">Maps</a></li><li class="portal-bar-item"><img alt="flag" src="//upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/21px-Flag_of_the_United_States.svg.png" decoding="async" width="21" height="11" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/32px-Flag_of_the_United_States.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/42px-Flag_of_the_United_States.svg.png 2x" data-file-width="1235" data-file-height="650" /> <a href="/wiki/Portal:United_States" title="Portal:United States">United States</a></li><li class="portal-bar-item"><a href="/wiki/File:The_Earth_seen_from_Apollo_17.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/The_Earth_seen_from_Apollo_17.jpg/19px-The_Earth_seen_from_Apollo_17.jpg" decoding="async" width="19" height="19" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/The_Earth_seen_from_Apollo_17.jpg/29px-The_Earth_seen_from_Apollo_17.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/97/The_Earth_seen_from_Apollo_17.jpg/38px-The_Earth_seen_from_Apollo_17.jpg 2x" data-file-width="3000" data-file-height="3002" /></a> <a href="/wiki/Portal:World" title="Portal:World">World</a></li></ul></div> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=46" title="Edit section: Notes">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-78"><a href="#cite_ref-78">^</a> In fact, the ship is unlikely to be at precisely 0m, because of tides and other factors which create a discrepancy between mean sea level and actual sea level. In the open ocean, high and low tide typically only differ by about 0.6m, but there are locations closer to land where they can differ by over 15m. See <a href="/wiki/Tidal_range" title="Tidal range">tidal range</a> for more details and references. </li> <li id="cite_note-211"><a href="#cite_ref-211">^</a> Orbital periods and speeds are calculated using the relations 4π2R3 = T2GM and V2R = GM, where R is the radius of orbit in metres; T is the orbital period in seconds; V is the orbital speed in m/s; G is the gravitational constant, approximately 6.673×10−11 Nm2/kg2; M is the mass of Earth, approximately 5.98×1024 kg (1.318×1025 lb). </li> <li id="cite_note-212"><a href="#cite_ref-212">^</a> Approximately 8.6 times when the Moon is nearest (that is, <style data-mw-deduplicate="TemplateStyles:r1214402035">.mw-parser-output .sfrac{white-space:nowrap}.mw-parser-output .sfrac.tion,.mw-parser-output .sfrac .tion{display:inline-block;vertical-align:-0.5em;font-size:85%;text-align:center}.mw-parser-output .sfrac .num{display:block;line-height:1em;margin:0.0em 0.1em;border-bottom:1px solid}.mw-parser-output .sfrac .den{display:block;line-height:1em;margin:0.1em 0.1em}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}</style>⁠363,104 km/42,164 km⁠), to 9.6 times when the Moon is farthest (that is, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1214402035">⁠405,696 km/42,164 km⁠) </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=47" title="Edit section: References">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-time-gps-cost-1">^ <a href="#cite_ref-time-gps-cost_1-0">a</a> <a href="#cite_ref-time-gps-cost_1-1">b</a> <style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.gps.gov/policy/funding/2023/">"Fiscal Year 2023 Program Funding"</a>. 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Retrieved June 20, 2011.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Aviation+Week&rft.atitle=LightSquared+Tests+Confirm+GPS+Jamming&rft_id=http%3A%2F%2Fwww.aviationweek.com%2Faw%2Fgeneric%2Fstory.jsp%3Fid%3Dnews%2Fawx%2F2011%2F06%2F09%2Fawx_06_09_2011_p0-334122.xml%26headline%3DLightSquared%2520Tests%2520Confirm%2520GPS%2520Jamming%26channel%3Dbusav&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"> </li> <li id="cite_note-171"><a href="#cite_ref-171">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.navcen.uscg.gov/?pageName=gpsAlmanacs">"GPS Almanacs, NANUS, and Ops Advisories (including archives)"</a>. GPS Almanac Information. 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So why is there no backup?"</a>. <a href="/wiki/NPR" title="NPR">NPR</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Losing+GPS+would+cost+the+U.S.+%241+billion+a+day.+So+why+is+there+no+backup%3F&rft.date=2024-09-27&rft.aulast=Hegyi&rft.aufirst=Nate&rft.au=Wong%2C+Wailin&rft_id=https%3A%2F%2Fwww.npr.org%2F2024%2F09%2F27%2Fnx-s1-5127737%2Flosing-gps-would-cost-the-u-s-1-billion-a-day-so-why-is-there-no-backup&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"> </li> <li id="cite_note-220"><a href="#cite_ref-220">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGoward2019" class="citation web cs1">Goward, Dana (November 15, 2019). <a rel="nofollow" class="external text" href="https://www.gpsworld.com/china-leads-world-with-plan-for-comprehensive-pnt/">"China leads world with plan for 'comprehensive' PNT"</a>. GPS World.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=China+leads+world+with+plan+for+%27comprehensive%27+PNT&rft.pub=GPS+World&rft.date=2019-11-15&rft.aulast=Goward&rft.aufirst=Dana&rft_id=https%3A%2F%2Fwww.gpsworld.com%2Fchina-leads-world-with-plan-for-comprehensive-pnt%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=48" title="Edit section: Further reading">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><div class="side-box metadata side-box-right"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-abovebelow"> <a href="/wiki/Wikipedia:The_Wikipedia_Library" title="Wikipedia:The Wikipedia Library">Library resources</a> about Global Positioning System <hr /></div> <div class="side-box-flex"> <div class="side-box-text plainlist"><ul><li><a class="external text" href="https://ftl.toolforge.org/cgi-bin/ftl?st=wp&su=Global+Positioning+System">Resources in your library</a></li> <li><a class="external text" href="https://ftl.toolforge.org/cgi-bin/ftl?st=wp&su=Global+Positioning+System&library=0CHOOSE0">Resources in other libraries</a></li> </ul></div></div> </div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20131021060507/http://www.navcen.uscg.gov/pubs/gps/gpsuser/gpsuser.pdf">"NAVSTAR GPS User Equipment Introduction"</a> (PDF). United States Coast Guard. September 1996. Archived from <a rel="nofollow" class="external text" href="http://www.navcen.uscg.gov/pubs/gps/gpsuser/gpsuser.pdf">the original</a> (PDF) on October 21, 2013. Retrieved August 22, 2008.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=NAVSTAR+GPS+User+Equipment+Introduction&rft.pub=United+States+Coast+Guard&rft.date=1996-09&rft_id=http%3A%2F%2Fwww.navcen.uscg.gov%2Fpubs%2Fgps%2Fgpsuser%2Fgpsuser.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFParkinsonSpilker1996" class="citation book cs1">Parkinson; Spilker (1996). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=lvI1a5J_4ewC">The global positioning system</a>. American Institute of Aeronautics and Astronautics. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-56347-106-3" title="Special:BookSources/978-1-56347-106-3"><bdi>978-1-56347-106-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+global+positioning+system&rft.pub=American+Institute+of+Aeronautics+and+Astronautics&rft.date=1996&rft.isbn=978-1-56347-106-3&rft.au=Parkinson&rft.au=Spilker&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DlvI1a5J_4ewC&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMendizabalBerenguerMelendez2009" class="citation book cs1">Mendizabal, Jaizki; Berenguer, Roc; Melendez, Juan (2009). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=t1lBTH42mOcC">GPS and Galileo</a>. McGraw Hill. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-07-159869-9" title="Special:BookSources/978-0-07-159869-9"><bdi>978-0-07-159869-9</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=GPS+and+Galileo&rft.pub=McGraw+Hill&rft.date=2009&rft.isbn=978-0-07-159869-9&rft.aulast=Mendizabal&rft.aufirst=Jaizki&rft.au=Berenguer%2C+Roc&rft.au=Melendez%2C+Juan&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3Dt1lBTH42mOcC&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBowditch2002" class="citation book cs1">Bowditch, Nathaniel (2002). <a class="external text" href="https://en.wikisource.org/wiki/The_American_Practical_Navigator">The American Practical Navigator – Chapter 11 Satellite Navigation </a>. United States government.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+American+Practical+Navigator+%E2%80%93+Chapter+11+Satellite+Navigation&rft.pub=United+States+government&rft.date=2002&rft.aulast=Bowditch&rft.aufirst=Nathaniel&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"></li> <li><a rel="nofollow" class="external text" href="http://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/12-540-principles-of-the-global-positioning-system-spring-2012/">Global Positioning System</a>. Open Courseware from <a href="/wiki/MIT" class="mw-redirect" title="MIT">Massachusetts Institute of Technology</a>, 2012.</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMilner2016" class="citation book cs1">Milner, Greg (2016). Pinpoint: How GPS is Changing Technology, Culture, and Our Minds. W. W. Norton. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-393-08912-7" title="Special:BookSources/978-0-393-08912-7"><bdi>978-0-393-08912-7</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Pinpoint%3A+How+GPS+is+Changing+Technology%2C+Culture%2C+and+Our+Minds&rft.pub=W.+W.+Norton&rft.date=2016&rft.isbn=978-0-393-08912-7&rft.aulast=Milner&rft.aufirst=Greg&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGlobal+Positioning+System" class="Z3988"></li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2>[<a href="/w/index.php?title=Global_Positioning_System&action=edit&section=49" title="Edit section: External links">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1235681985"><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-flex"> <div class="side-box-image"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></div> <div class="side-box-text plainlist">Wikimedia Commons has media related to <a href="https://commons.wikimedia.org/wiki/Global_Positioning_System" class="extiw" title="commons:Global Positioning System">Global Positioning System</a>.</div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/gps/">FAA GPS FAQ</a></li> <li><a rel="nofollow" class="external text" href="https://www.gps.gov/">GPS.gov</a> – General public education website created by the U.S. Government</li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="NAVSTAR_Global_Positioning_System_satellites" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:GPS_satellites" title="Template:GPS satellites"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:GPS_satellites" title="Template talk:GPS satellites"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:GPS_satellites" title="Special:EditPage/Template:GPS satellites"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="NAVSTAR_Global_Positioning_System_satellites" style="font-size:114%;margin:0 4em">NAVSTAR <a class="mw-selflink selflink">Global Positioning System</a> <a href="/wiki/GPS_satellite_blocks" title="GPS satellite blocks">satellites</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div><a href="/wiki/List_of_GPS_satellites" title="List of GPS satellites">List of GPS satellites</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_(satellite)#Block_I_satellites" class="mw-redirect" title="GPS (satellite)">Block I</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/OPS_5111" title="OPS 5111">1</a></li> <li><a href="/wiki/OPS_5112" title="OPS 5112">2</a></li> <li><a href="/wiki/OPS_5113" title="OPS 5113">3</a></li> <li><a href="/wiki/OPS_5114" title="OPS 5114">4</a></li> <li><a href="/wiki/OPS_5117" title="OPS 5117">5</a></li> <li><a href="/wiki/OPS_5118" title="OPS 5118">6</a></li> <li><a href="/wiki/Navstar_7" title="Navstar 7">7</a>†</li> <li><a href="/wiki/OPS_9794" title="OPS 9794">8</a></li> <li><a href="/wiki/USA-1_(satellite)" title="USA-1 (satellite)">9</a></li> <li><a href="/wiki/USA-5" title="USA-5">10</a></li> <li><a href="/wiki/USA-10" title="USA-10">11</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_(satellite)#Block_II_satellites" class="mw-redirect" title="GPS (satellite)">Block II</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/USA-35" title="USA-35">1</a></li> <li><a href="/wiki/USA-38" title="USA-38">2</a></li> <li><a href="/wiki/USA-42" title="USA-42">3</a></li> <li><a href="/wiki/USA-47" title="USA-47">4</a></li> <li><a href="/wiki/USA-49" title="USA-49">5</a></li> <li><a href="/wiki/USA-50" title="USA-50">6</a></li> <li><a href="/wiki/USA-54" title="USA-54">7</a></li> <li><a href="/wiki/USA-63" title="USA-63">8</a></li> <li><a href="/wiki/USA-64" title="USA-64">9</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_(satellite)#Block_IIA_series" class="mw-redirect" title="GPS (satellite)">Block IIA</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/USA-66" title="USA-66">1</a></li> <li><a href="/wiki/USA-71" title="USA-71">2</a></li> <li><a href="/wiki/USA-79" title="USA-79">3</a></li> <li><a href="/wiki/USA-80" title="USA-80">4</a></li> <li><a href="/wiki/USA-83" title="USA-83">5</a></li> <li><a href="/wiki/USA-84" title="USA-84">6</a></li> <li><a href="/wiki/USA-85" title="USA-85">7</a></li> <li><a href="/wiki/USA-87" title="USA-87">8</a></li> <li><a href="/wiki/USA-88" title="USA-88">9</a></li> <li><a href="/wiki/USA-90" title="USA-90">10</a></li> <li><a href="/wiki/USA-91" title="USA-91">11</a></li> <li><a href="/wiki/USA-92" title="USA-92">12</a></li> <li><a href="/wiki/USA-94" title="USA-94">13</a></li> <li><a href="/wiki/USA-96" title="USA-96">14</a></li> <li><a href="/wiki/USA-100" title="USA-100">15</a></li> <li><a href="/wiki/USA-117" title="USA-117">16</a></li> <li><a href="/wiki/USA-126" title="USA-126">17</a></li> <li><a href="/wiki/USA-128" title="USA-128">18</a></li> <li><a href="/wiki/USA-135" title="USA-135">19</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_(satellite)#Block_IIR_series" class="mw-redirect" title="GPS (satellite)">Block IIR</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/GPS_IIR-1" title="GPS IIR-1">1</a>†</li> <li><a href="/wiki/USA-132" title="USA-132">2</a></li> <li><a href="/wiki/USA-145" title="USA-145">3</a></li> <li><a href="/wiki/USA-150" title="USA-150">4</a></li> <li><a href="/wiki/USA-151" title="USA-151">5</a></li> <li><a href="/wiki/USA-154" title="USA-154">6</a></li> <li><a href="/wiki/USA-156" title="USA-156">7</a></li> <li><a href="/wiki/USA-166" title="USA-166">8</a></li> <li><a href="/wiki/USA-168" title="USA-168">9</a></li> <li><a href="/wiki/USA-175" title="USA-175">10</a></li> <li><a href="/wiki/USA-177" title="USA-177">11</a></li> <li><a href="/wiki/USA-178" title="USA-178">12</a></li> <li><a href="/wiki/USA-180" title="USA-180">13</a></li> <li><a href="/wiki/USA-183" title="USA-183">14</a></li> <li><a href="/wiki/USA-190" title="USA-190">15</a></li> <li><a href="/wiki/USA-192" title="USA-192">16</a></li> <li><a href="/wiki/USA-196" title="USA-196">17</a></li> <li><a href="/wiki/USA-199" title="USA-199">18</a></li> <li><a href="/wiki/USA-201" title="USA-201">19</a></li> <li><a href="/wiki/USA-203" title="USA-203">20</a></li> <li><a href="/wiki/USA-206" title="USA-206">21</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_(satellite)#Block_IIRM" class="mw-redirect" title="GPS (satellite)">Block IIRM</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/USA-183" title="USA-183">1</a></li> <li><a href="/wiki/USA-190" title="USA-190">2</a></li> <li><a href="/wiki/USA-192" title="USA-192">3</a></li> <li><a href="/wiki/USA-196" title="USA-196">4</a></li> <li><a href="/wiki/USA-199" title="USA-199">5</a></li> <li><a href="/wiki/USA-201" title="USA-201">6</a></li> <li><a href="/wiki/USA-203" title="USA-203">7</a></li> <li><a href="/wiki/USA-206" title="USA-206">8</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_Block_IIF" title="GPS Block IIF">Block IIF</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/USA-213" title="USA-213">1</a></li> <li><a href="/wiki/USA-232" title="USA-232">2</a></li> <li><a href="/wiki/USA-239" title="USA-239">3</a></li> <li><a href="/wiki/USA-242" title="USA-242">4</a></li> <li><a href="/wiki/USA-248" title="USA-248">5</a></li> <li><a href="/wiki/USA-251" title="USA-251">6</a></li> <li><a href="/wiki/USA-256" title="USA-256">7</a></li> <li><a href="/wiki/USA-258" title="USA-258">8</a></li> <li><a href="/wiki/USA-260" title="USA-260">9</a></li> <li><a href="/wiki/USA-262" title="USA-262">10</a></li> <li><a href="/wiki/USA-265" title="USA-265">11</a></li> <li><a href="/wiki/USA-266" title="USA-266">12</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_Block_III" title="GPS Block III">Block III</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/USA-289" title="USA-289">01</a></li> <li><a href="/wiki/USA-293" title="USA-293">02</a></li> <li><a href="/wiki/USA-304" title="USA-304">03</a></li> <li><a href="/wiki/USA-309" title="USA-309">04</a></li> <li><a href="/wiki/USA-319" title="USA-319">05</a></li> <li><a href="/wiki/USA-343" title="USA-343">06</a></li> <li><a href="/w/index.php?title=GPS_III-07&action=edit&redlink=1" class="new" title="GPS III-07 (page does not exist)">07</a></li> <li><a href="/w/index.php?title=GPS_III-08&action=edit&redlink=1" class="new" title="GPS III-08 (page does not exist)">08</a></li> <li><a href="/w/index.php?title=GPS_III-09&action=edit&redlink=1" class="new" title="GPS III-09 (page does not exist)">09</a></li> <li><a href="/w/index.php?title=GPS_III-10&action=edit&redlink=1" class="new" title="GPS III-10 (page does not exist)">10</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GPS_Block_IIIF" title="GPS Block IIIF">Block IIIF</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/w/index.php?title=GPS_IIIF-11&action=edit&redlink=1" class="new" title="GPS IIIF-11 (page does not exist)">11</a></li> <li><a href="/w/index.php?title=GPS_IIIF-12&action=edit&redlink=1" class="new" title="GPS IIIF-12 (page does not exist)">12</a></li> <li><a href="/w/index.php?title=GPS_IIIF-13&action=edit&redlink=1" class="new" title="GPS IIIF-13 (page does not exist)">13</a></li> <li><a href="/w/index.php?title=GPS_IIIF-14&action=edit&redlink=1" class="new" title="GPS IIIF-14 (page does not exist)">14</a></li> <li><a href="/w/index.php?title=GPS_IIIF-15&action=edit&redlink=1" class="new" title="GPS IIIF-15 (page does not exist)">15</a></li> <li><a href="/w/index.php?title=GPS_IIIF-16&action=edit&redlink=1" class="new" title="GPS IIIF-16 (page does not exist)">16</a></li> <li><a href="/w/index.php?title=GPS_IIIF-17&action=edit&redlink=1" class="new" title="GPS IIIF-17 (page does not exist)">17</a></li> <li><a href="/w/index.php?title=GPS_IIIF-18&action=edit&redlink=1" class="new" title="GPS IIIF-18 (page does not exist)">18</a></li> <li><a href="/w/index.php?title=GPS_IIIF-19&action=edit&redlink=1" class="new" title="GPS IIIF-19 (page does not exist)">19</a></li> <li><a href="/w/index.php?title=GPS_IIIF-20&action=edit&redlink=1" class="new" title="GPS IIIF-20 (page does not exist)">20</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>Italics indicate future missions. Signs † indicate launch failures.</div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Satellite_navigation_systems" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Satellite_navigation_systems" title="Template:Satellite navigation systems"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a 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navigation)">Galileo</a></li> <li><a href="/wiki/GLONASS" title="GLONASS">GLONASS</a></li> <li><a class="mw-selflink selflink">GPS / NavStar</a></li> <li><a href="/wiki/Indian_Regional_Navigation_Satellite_System" title="Indian Regional Navigation Satellite System">IRNSS / NAVIC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Historical</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BeiDou#BeiDou-1" title="BeiDou">BDS / BeiDou-1</a></li> <li><a href="/wiki/Transit_(satellite)" title="Transit (satellite)">Transit</a></li> <li><a href="/wiki/Timation" title="Timation">Timation</a></li> <li><a href="/wiki/Tsiklon_(satellite)" class="mw-redirect" title="Tsiklon (satellite)">Tsiklon</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/GNSS_augmentation" title="GNSS augmentation">GNSS augmentation</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/European_Geostationary_Navigation_Overlay_Service" title="European Geostationary Navigation Overlay Service">EGNOS</a></li> <li><a href="/wiki/GPS_Aided_GEO_Augmented_Navigation" class="mw-redirect" title="GPS Aided GEO Augmented Navigation">GAGAN</a></li> <li><a href="/wiki/GPS%C2%B7C" title="GPS·C">GPS·C</a> (retired)</li> <li><a href="/wiki/Joint_Precision_Approach_and_Landing_System" class="mw-redirect" title="Joint Precision Approach and Landing System">JPALS</a></li> <li><a href="/wiki/Local_Area_Augmentation_System" class="mw-redirect" title="Local Area Augmentation System">LAAS</a></li> <li><a href="/wiki/MTSAT_Satellite_Augmentation_System" title="MTSAT Satellite Augmentation System">MSAS</a></li> <li><a href="/wiki/Networked_Transport_of_RTCM_via_Internet_Protocol" title="Networked Transport of RTCM via Internet Protocol">NTRIP</a></li> <li><a href="/wiki/Quasi-Zenith_Satellite_System" title="Quasi-Zenith Satellite System">QZSS / Michibiki</a></li> <li><a href="/wiki/Southern_Positioning_Augmentation_Network" title="Southern Positioning Augmentation Network">SouthPAN</a></li> <li><a href="/wiki/StarFire_(navigation_system)" title="StarFire (navigation system)">StarFire</a></li> <li><a href="/wiki/Wide_Area_Augmentation_System" title="Wide Area Augmentation System">WAAS</a></li> <li><a href="/wiki/System_for_Differential_Corrections_and_Monitoring" title="System for Differential Corrections and Monitoring">SDCM</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related topics</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/GNSS_reflectometry" title="GNSS reflectometry">GNSS reflectometry</a></li> <li><a href="/wiki/Kalman_filter" title="Kalman filter">Kalman filter</a></li> <li><a href="/wiki/United_Kingdom_Global_Navigation_Satellite_System" title="United Kingdom Global Navigation Satellite System">United Kingdom Global Navigation Satellite System</a></li> <li><a href="/wiki/Wavelet" title="Wavelet">Wavelet</a></li> <li><a href="/wiki/RINEX" title="RINEX">RINEX</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Satellite_constellations" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Satellite_constellations" title="Template:Satellite constellations"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Satellite_constellations" title="Template talk:Satellite constellations"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Satellite_constellations" title="Special:EditPage/Template:Satellite constellations"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Satellite_constellations" style="font-size:114%;margin:0 4em"><a href="/wiki/Satellite_constellation" title="Satellite constellation">Satellite constellations</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Satellite_navigation" title="Satellite navigation">Navigation</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BeiDou" title="BeiDou">BeiDou</a></li> <li><a href="/wiki/Galileo_(satellite_navigation)" title="Galileo (satellite navigation)">Galileo</a></li> <li><a href="/wiki/GLONASS" title="GLONASS">GLONASS</a></li> <li><a class="mw-selflink selflink">GPS</a></li> <li><a href="/wiki/Indian_Regional_Navigation_Satellite_System" title="Indian Regional Navigation Satellite System">IRNSS</a></li> <li><a href="/wiki/Quasi-Zenith_Satellite_System" title="Quasi-Zenith Satellite System">QZSS</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Communications_satellite" title="Communications satellite">Communication</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Operational</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Broadband_Global_Area_Network" title="Broadband Global Area Network">BGAN</a></li> <li><a href="/wiki/Defense_Satellite_Communications_System" title="Defense Satellite Communications System">DSCS</a></li> <li><a href="/wiki/Globalstar" title="Globalstar">Globalstar</a></li> <li><a href="/wiki/Iridium_satellite_constellation" title="Iridium satellite constellation">Iridium</a></li> <li><a href="/wiki/O3b_(satellite)" class="mw-redirect" title="O3b (satellite)">O3b</a></li> <li><a href="/wiki/Orbcomm_(satellite)" title="Orbcomm (satellite)">Orbcomm</a></li> <li><a href="/wiki/Starlink" title="Starlink">Starlink</a></li> <li><a href="/wiki/Tianlian" title="Tianlian">Tianlian</a></li> <li><a href="/wiki/Tracking_and_data_relay_satellite" title="Tracking and data relay satellite">TDRS</a></li> <li><a href="/wiki/Viasat,_Inc." class="mw-redirect" title="Viasat, Inc.">ViaSat</a></li> <li><a href="/wiki/Wideband_Global_SATCOM" title="Wideband Global SATCOM">WGS</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Proposed</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IRIS%C2%B2" title="IRIS²">IRIS²</a></li> <li><a href="/wiki/Eutelsat_OneWeb" title="Eutelsat OneWeb">OneWeb</a></li> <li><a href="/wiki/O3b_mPOWER" title="O3b mPOWER">O3b mPOWER</a></li> <li><a href="/wiki/Kuiper_Systems" title="Kuiper Systems">Kuiper Systems</a></li> <li><a href="/wiki/AST_SpaceMobile" title="AST SpaceMobile">SpaceMobile</a></li> <li><a href="/wiki/Thousand_Sails" class="mw-redirect" title="Thousand Sails">Thousand Sails</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Abandoned</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Celestri" title="Celestri">Celestri</a></li> <li><a href="/wiki/Teledesic" title="Teledesic">Teledesic</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Earth_observation_satellite" title="Earth observation satellite">Observation</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Planet_Labs" title="Planet Labs">Planet</a></li> <li><a href="/wiki/Pleiades_(satellite)" class="mw-redirect" title="Pleiades (satellite)">Pleiades</a></li> <li><a href="/wiki/RapidEye" title="RapidEye">RapidEye</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Time_signal_stations" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Time_signal_stations" title="Template:Time signal stations"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Time_signal_stations" title="Template talk:Time signal stations"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Time_signal_stations" title="Special:EditPage/Template:Time signal stations"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Time_signal_stations" style="font-size:114%;margin:0 4em"><a href="/wiki/Radio_clock" title="Radio clock">Time signal stations</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Longwave" title="Longwave">Longwave</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BPC_(time_signal)" title="BPC (time signal)">BPC</a></li> <li><a href="/wiki/BPL_(time_service)" title="BPL (time service)">BPL</a></li> <li><a href="/wiki/BSF_(time_service)" title="BSF (time service)">BSF</a></li> <li><a href="/wiki/Beta_(time_signal)" title="Beta (time signal)">Beta</a></li> <li><a href="/wiki/DCF77" title="DCF77">DCF77</a></li> <li><a href="/wiki/JJY" title="JJY">JJY</a></li> <li><a href="/wiki/RBU_(radio_station)" title="RBU (radio station)">RBU</a></li> <li><a href="/wiki/RTZ_(radio_station)" title="RTZ (radio station)">RTZ</a></li> <li><a href="/wiki/ALS162_time_signal" title="ALS162 time signal">TDF time signal</a></li> <li><a href="/wiki/Time_from_NPL_(MSF)" title="Time from NPL (MSF)">Time from NPL</a></li> <li><a href="/wiki/WWVB" title="WWVB">WWVB</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/High_frequency" title="High frequency">Shortwave</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BPM_(time_service)" title="BPM (time service)">BPM</a></li> <li><a href="/wiki/CHU_(radio_station)" title="CHU (radio station)">CHU</a></li> <li><a href="/wiki/HD2IOA" title="HD2IOA">HD2IOA</a></li> <li><a href="/wiki/HLA_(radio_station)" title="HLA (radio station)">HLA</a></li> <li><a href="/wiki/JN53DV" title="JN53DV">JN53DV</a></li> <li><a href="/wiki/ROA_Time" title="ROA Time">ROA Time</a></li> <li><a href="/wiki/RWM" title="RWM">RWM</a></li> <li><a href="/wiki/WWV_(radio_station)" title="WWV (radio station)">WWV</a></li> <li><a href="/wiki/WWVH" title="WWVH">WWVH</a></li> <li><a href="/wiki/YVTO" title="YVTO">YVTO</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Very-high_frequency" class="mw-redirect" title="Very-high frequency">VHF</a>/<a href="/wiki/FM_band" class="mw-redirect" title="FM band">FM</a>/<a href="/wiki/Ultra-high_frequency" class="mw-redirect" title="Ultra-high frequency">UHF</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Radio_Data_System" title="Radio Data System">Radio Data System</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Satellite_navigation" title="Satellite navigation">Satellite</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BeiDou" title="BeiDou">BeiDou</a></li> <li><a href="/wiki/DORIS_(satellite_system)" title="DORIS (satellite system)">DORIS</a></li> <li><a href="/wiki/GLONASS" title="GLONASS">GLONASS</a></li> <li><a href="/wiki/Galileo_(satellite_navigation)" title="Galileo (satellite navigation)">Galileo</a></li> <li><a class="mw-selflink selflink">Global Positioning System</a></li> <li><a href="/wiki/Indian_Regional_Navigation_Satellite_System" title="Indian Regional Navigation Satellite System">IRNSS</a></li> <li><a href="/wiki/Quasi-Zenith_Satellite_System" title="Quasi-Zenith Satellite System">Quasi-Zenith Satellite System</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Defunct</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BSF_(time_service)" title="BSF (time service)">BSF</a></li> <li><a href="/wiki/HBG_(time_signal)" title="HBG (time signal)">HBG</a></li> <li><a href="/wiki/NAA_(Arlington,_Virginia)" title="NAA (Arlington, Virginia)">NAA</a></li> <li><a href="/wiki/OLB5" title="OLB5">OLB5</a></li> <li><a href="/wiki/OMA_(time_signal)" title="OMA (time signal)">OMA</a></li> <li><a href="/wiki/Radio_VNG" title="Radio VNG">Radio VNG</a></li> <li><a href="/wiki/WWVB" title="WWVB">WWVL</a></li> <li><a href="/wiki/Y3S" title="Y3S">Y3S</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494"></div><div role="navigation" class="navbox" aria-labelledby="USAF_and_USSF_space_vehicle_designations_(since_1962)" style=";wide;padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2" style="background-color:#C3D6EF;color:inherit;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/w/index.php?title=Template:USAF/USSF_space_vehicles&action=edit&redlink=1" class="new" title="Template:USAF/USSF space vehicles (page does not exist)"><abbr title="View this template" style="color:inherit">v</abbr></a></li><li class="nv-talk"><a href="/w/index.php?title=Template_talk:USAF/USSF_space_vehicles&action=edit&redlink=1" class="new" title="Template talk:USAF/USSF space vehicles (page does not exist)"><abbr title="Discuss this template" style="color:inherit">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:USAF/USSF_space_vehicles" title="Special:EditPage/Template:USAF/USSF space vehicles"><abbr title="Edit this template" style="color:inherit">e</abbr></a></li></ul></div><div id="USAF_and_USSF_space_vehicle_designations_(since_1962)" style="font-size:114%;margin:0 4em"><a href="/wiki/United_States_Air_Force" title="United States Air Force">USAF</a> and <a href="/wiki/United_States_Space_Force" title="United States Space Force">USSF</a> space vehicle designations (since 1962)</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">SLV series</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Scout_(rocket_family)" title="Scout (rocket family)">SLV-1 (Scout)</a></li> <li><a href="/wiki/Thor_(rocket_family)" title="Thor (rocket family)">SLV-2 (Thor)</a></li> <li><a href="/wiki/Atlas_(rocket_family)" title="Atlas (rocket family)">SLV-3 (Atlas)</a></li> <li><a href="/wiki/Titan_II_GLV" title="Titan II GLV">SLV-4 (Titan II)</a></li> <li><a href="/wiki/Titan_(rocket_family)" title="Titan (rocket family)">SLV-5 (Titan)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">SB series</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/SM-65E_Atlas" title="SM-65E Atlas">SB-1</a></li> <li><a href="/wiki/Atlas_II" title="Atlas II">SB-2</a></li> <li><a href="/wiki/Delta_II" title="Delta II">SB-3</a></li> <li><a href="/wiki/Titan_23G" title="Titan 23G">SB-4</a></li> <li><a href="/wiki/Titan_IV" title="Titan IV">SB-5</a></li> <li><a href="/wiki/Titan_34D" title="Titan 34D">SB-6</a></li> <li><a href="/wiki/Inertial_Upper_Stage" title="Inertial Upper Stage">SSB-7</a></li> <li><a href="/wiki/Centaur_(rocket_stage)" title="Centaur (rocket stage)">SSB-8</a></li> <li><a href="/wiki/Payload_Assist_Module" title="Payload Assist Module">SSB-9</a></li> <li><a href="/wiki/Transtage" title="Transtage">SSB-10</a></li> <li><a href="/wiki/Pegasus_(rocket)" class="mw-redirect" title="Pegasus (rocket)">ASB-11</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;">Satellites</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Defense_Meteorological_Satellite_Program" title="Defense Meteorological Satellite Program">WS-1</a></li> <li><a href="/wiki/Defense_Meteorological_Satellite_Program" title="Defense Meteorological Satellite Program">WS-2</a></li> <li><a href="/w/index.php?title=IMEWS&action=edit&redlink=1" class="new" title="IMEWS (page does not exist)">LS-3</a></li> <li><a href="/wiki/Defense_Satellite_Communications_System" title="Defense Satellite Communications System">ES-4</a></li> <li><a href="/wiki/Defense_Satellite_Communications_System" title="Defense Satellite Communications System">ES-5</a></li> <li><a href="/w/index.php?title=Boost_Surveillance_Tracking_System&action=edit&redlink=1" class="new" title="Boost Surveillance Tracking System (page does not exist)">LS-6</a></li> <li><a class="mw-selflink selflink">NS-7</a></li> <li><a href="/wiki/Milstar" title="Milstar">ES-8</a></li> <li><a href="/wiki/Space_Surveillance_and_Tracking_System" class="mw-redirect" title="Space Surveillance and Tracking System">LS-9</a></li> <li><a href="/w/index.php?title=Space-Based_Radar_(USAF)&action=edit&redlink=1" class="new" title="Space-Based Radar (USAF) (page does not exist)">LS-10</a> (I)</li> <li><a href="/wiki/XSS-10" title="XSS-10">XSS-10</a> (II)</li> <li><a href="/wiki/USA-165" title="USA-165">XSS-11</a>2</li> <li><a href="/w/index.php?title=XSS-12&action=edit&redlink=1" class="new" title="XSS-12 (page does not exist)">XSS-12</a></li> <li>S-131</li> <li><a href="/wiki/Wideband_Global_SATCOM" title="Wideband Global SATCOM">ES-14</a></li> <li><a href="/wiki/Space_Based_Space_Surveillance" title="Space Based Space Surveillance">LS-15</a>3</li> <li><a href="/wiki/Space-Based_Infrared_System" title="Space-Based Infrared System">LS-16</a>3</li> <li><a href="/wiki/Advanced_Extremely_High_Frequency" title="Advanced Extremely High Frequency">ES-17</a></li> <li><a href="/wiki/GOES_13" title="GOES 13">EWS-G1</a></li> <li><a href="/wiki/GOES_15" title="GOES 15">EWS-G2</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2" style="background-color:#DCDCDC;color:inherit;"><div> <ul><li>1 Not assigned</li> <li>2 Unofficial designation</li> <li>3 Designation believed to be this type but unconfirmed</li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Equipment_of_the_United_States_Air_Force" style=";wide;padding:3px"><table class="nowraplinks mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2" style="background-color:#C3D6EF;color:inherit;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:USAF_equipment" title="Template:USAF equipment"><abbr title="View this template" style="color:inherit">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:USAF_equipment" title="Template talk:USAF equipment"><abbr title="Discuss this template" style="color:inherit">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:USAF_equipment" title="Special:EditPage/Template:USAF equipment"><abbr title="Edit this template" style="color:inherit">e</abbr></a></li></ul></div><div id="Equipment_of_the_United_States_Air_Force" style="font-size:114%;margin:0 4em"><a href="/wiki/List_of_equipment_of_the_United_States_Air_Force" title="List of equipment of the United States Air Force">Equipment of the United States Air Force</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;text-align:center;">Ground systems</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0;;wide"><tbody><tr><th id="C2" scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;text-align:center; font-weight:normal;"><a href="/wiki/Command_and_control" title="Command and control">C2</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_and_Space_Operations_Center" class="mw-redirect" title="Air and Space Operations Center">AN/USQ-163 Falconer</a></li> <li><a href="/wiki/Distributed_Common_Ground_System" title="Distributed Common Ground System">AN/GSQ-272 Sentinel</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;text-align:center; font-weight:normal;">Ground vehicle</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Humvee" title="Humvee">HMMWV</a></li> <li><a href="/wiki/Commercial_Utility_Cargo_Vehicle#LSSV" title="Commercial Utility Cargo Vehicle">LSSV</a></li> <li><a href="/w/index.php?title=R-5_Refueler&action=edit&redlink=1" class="new" title="R-5 Refueler (page does not exist)">R-5 Refueler</a></li> <li><a href="/w/index.php?title=R-9_Refueler&action=edit&redlink=1" class="new" title="R-9 Refueler (page does not exist)">R-9 Refueler</a></li> <li><a href="/wiki/R-11_Refueler" title="R-11 Refueler">R-11 Refueler</a></li> <li>C300</li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;text-align:center;">Munitions</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0;;wide"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal;">Bomb</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Mark_82_bomb" title="Mark 82 bomb">Mk-82</a></li> <li><a href="/wiki/Mark_84_bomb" title="Mark 84 bomb">Mk-84</a></li> <li><a href="/wiki/GBU-8" title="GBU-8">GBU-8</a></li> <li><a href="/wiki/GBU-10_Paveway_II" title="GBU-10 Paveway II">GBU-10 Paveway II</a></li> <li><a href="/wiki/GBU-12_Paveway_II" title="GBU-12 Paveway II">GBU-12 Paveway II</a></li> <li><a href="/wiki/GBU-15" title="GBU-15">GBU-15</a></li> <li><a href="/wiki/GBU-24_Paveway_III" title="GBU-24 Paveway III">GBU-24 Paveway III</a></li> <li><a href="/wiki/GBU-27_Paveway_III" title="GBU-27 Paveway III">GBU-27 Paveway III</a></li> <li><a href="/wiki/GBU-28" title="GBU-28">GBU-28</a></li> <li><a href="/wiki/Joint_Direct_Attack_Munition" title="Joint Direct Attack Munition">GBU-31, GB-32, GB-38 JDAM</a></li> <li><a href="/wiki/GBU-39_Small_Diameter_Bomb" title="GBU-39 Small Diameter Bomb">GBU-39 Small Diameter Bomb</a></li> <li><a href="/wiki/GBU-44/B_Viper_Strike" title="GBU-44/B Viper Strike">GBU-44/B Viper Strike</a></li> <li><a href="/wiki/GBU-53/B" class="mw-redirect" title="GBU-53/B">GBU-53/B Small Diameter Bomb II</a></li> <li><a href="/wiki/Joint_Direct_Attack_Munition" title="Joint Direct Attack Munition">GBU-54 Laser JDAM</a></li> <li><a href="/wiki/GBU-72" title="GBU-72">GBU-72</a></li> <li><a href="/wiki/CBU-87_Combined_Effects_Munition" title="CBU-87 Combined Effects Munition">CBU-87 Combined Effects Munition</a></li> <li><a href="/wiki/GATOR_mine_system" title="GATOR mine system">CBU-89 Gator</a></li> <li><a href="/wiki/CBU-97_Sensor_Fuzed_Weapon" title="CBU-97 Sensor Fuzed Weapon">CBU-97 Sensor Fuzed Weapon</a></li> <li><a href="/wiki/BLU-109_bomb" title="BLU-109 bomb">BLU-109 bomb</a></li> <li><a href="/wiki/BLU-116" title="BLU-116">BLU-116 Bunker Buster</a></li> <li><a href="/wiki/B61_nuclear_bomb" title="B61 nuclear bomb">B61 nuclear bomb</a></li> <li><a href="/wiki/B83_nuclear_bomb" title="B83 nuclear bomb">B83 nuclear bomb</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal;">Gun</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/GAU-8_Avenger" title="GAU-8 Avenger">GAU-8 Avenger</a></li> <li><a href="/wiki/M61_Vulcan" title="M61 Vulcan">M61 Vulcan</a></li> <li><a href="/wiki/GAU-12_Equalizer" title="GAU-12 Equalizer">GAU-12</a></li> <li><a href="/wiki/GAU-13" title="GAU-13">GAU-13</a></li> <li><a href="/wiki/GAU-19" title="GAU-19">GAU-19</a></li> <li><a href="/wiki/M240_machine_gun" title="M240 machine gun">M240</a></li> <li><a href="/wiki/Bofors_40_mm_Automatic_Gun_L/60" class="mw-redirect" title="Bofors 40 mm Automatic Gun L/60">L/60 Bofors</a></li> <li><a href="/wiki/M102_howitzer" title="M102 howitzer">M102 howitzer</a></li> <li><a href="/wiki/Mk44_Bushmaster_II" title="Mk44 Bushmaster II">GAU-23/A</a></li> <li><a href="/wiki/M2_Browning" title="M2 Browning">M2 Browning</a></li> <li><a href="/wiki/M134_Minigun" title="M134 Minigun">M134 Minigun</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal;">Missile</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/AIM-7_Sparrow" title="AIM-7 Sparrow">AIM-7 Sparrow</a></li> <li><a href="/wiki/AIM-9_Sidewinder" title="AIM-9 Sidewinder">AIM-9 Sidewinder</a></li> <li><a href="/wiki/LGM-30_Minuteman" title="LGM-30 Minuteman">LGM-30G Minuteman III</a></li> <li><a href="/wiki/AGM-65_Maverick" title="AGM-65 Maverick">AGM-65 Maverick</a></li> <li><a href="/wiki/Harpoon_(missile)" title="Harpoon (missile)">AGM-84 Harpoon</a></li> <li><a href="/wiki/AGM-84E_Standoff_Land_Attack_Missile" title="AGM-84E Standoff Land Attack Missile">AGM-84E Standoff Land Attack Missile</a></li> <li><a href="/wiki/AGM-84H/K_SLAM-ER" title="AGM-84H/K SLAM-ER">AGM-84H/K Standoff Land Attack Missile - Expanded Response</a></li> <li><a href="/wiki/AGM-86_ALCM" title="AGM-86 ALCM">AGM-86 ALCM</a></li> <li><a href="/wiki/AGM-88_HARM" title="AGM-88 HARM">AGM-88 HARM</a></li> <li><a href="/wiki/AGM-114_Hellfire" title="AGM-114 Hellfire">AGM-114 Hellfire</a></li> <li><a href="/wiki/AIM-120_AMRAAM" title="AIM-120 AMRAAM">AIM-120 AMRAAM</a></li> <li><a href="/wiki/AGM-130" title="AGM-130">AGM-130 Powered Standoff Weapon</a></li> <li><a href="/wiki/AGM-154_Joint_Standoff_Weapon" title="AGM-154 Joint Standoff Weapon">AGM-154 Joint Standoff Weapon</a></li> <li><a href="/wiki/AGM-158_JASSM" title="AGM-158 JASSM">AGM-158 JASSM</a></li> <li><a href="/wiki/AGM-176_Griffin" title="AGM-176 Griffin">AGM-176 Griffin</a></li> <li><a href="/wiki/Zuni_(rocket)" title="Zuni (rocket)">Zuni rocket</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal;">Target</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ryan_Firebee" title="Ryan Firebee">BQM-34 Firebee</a></li> <li><a href="/wiki/Composite_Engineering_BQM-167_Skeeter" title="Composite Engineering BQM-167 Skeeter">BQM-167 Subscale Aerial Target</a></li> <li><a href="/wiki/Beechcraft_MQM-107_Streaker" title="Beechcraft MQM-107 Streaker">MQM-107 Streaker</a></li> <li><a href="/wiki/General_Dynamics_F-16_Fighting_Falcon#QF-16" title="General Dynamics F-16 Fighting Falcon">QF-16 Aerial Target</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;text-align:center;">Small arms</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0;;wide"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal; text-align:center;"><a href="/wiki/Service_pistol" title="Service pistol">Sidearm</a>/<a href="/wiki/Personal_defense_weapon" title="Personal defense weapon">PDW</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/SIG_Sauer_P226" title="SIG Sauer P226">M11 Pistol</a></li> <li><a href="/wiki/Beretta_M9" title="Beretta M9">M9 Pistol</a></li> <li><a href="/wiki/SIG_Sauer_M17" title="SIG Sauer M17">M17 Pistol</a></li> <li><a href="/wiki/Heckler_%26_Koch_MP5" title="Heckler & Koch MP5">MP5 submachine gun</a></li> <li>USAF Pilot's Survival Knife</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal; text-align:center;"><a href="/wiki/Service_rifle" title="Service rifle">Rifle</a>/<a href="/wiki/Carbine" title="Carbine">carbine</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/CAR-15#GUU-5/P" title="CAR-15">GUU-5/P Carbine</a></li> <li><a href="/wiki/M4_carbine" title="M4 carbine">M4 carbine</a></li> <li><a href="/wiki/M14_rifle" title="M14 rifle">M14 Stand-off Munitions Disruptor (SMUD)</a></li> <li><a href="/wiki/M16_rifle" title="M16 rifle">M16A2 Rifle</a></li> <li><a href="/wiki/M24_sniper_weapon_system" title="M24 sniper weapon system">M24 sniper weapon system</a></li> <li><a href="/wiki/Barrett_M82" title="Barrett M82">M107 Long Range Sniper Rifle</a></li> <li><a href="/wiki/Mk_14_Enhanced_Battle_Rifle" title="Mk 14 Enhanced Battle Rifle">Mk 14 Mod 0 Enhanced Battle Rifle</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal; text-align:center;"><a href="/wiki/Squad_automatic_weapon" title="Squad automatic weapon">Support</a>/<a href="/wiki/Close_combat" class="mw-redirect" title="Close combat">CQB</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/M60_machine_gun" title="M60 machine gun">M60 machine gun</a></li> <li><a href="/wiki/M2_Browning" title="M2 Browning">M2HB Browning machine gun</a></li> <li><a href="/wiki/M240_machine_gun" title="M240 machine gun">M240B Medium Machine Gun</a></li> <li><a href="/wiki/M249_light_machine_gun" title="M249 light machine gun">M249 light machine gun</a></li> <li><a href="/wiki/Benelli_M4" title="Benelli M4">M1014 shotgun</a></li> <li><a href="/wiki/Remington_Model_870" title="Remington Model 870">Remington 870 MCS shotgun</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;font-weight:normal; text-align:center;">Ordnance</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0;line-height:150%"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/AT4" title="AT4">M136 AT4 Light Anti-tank Weapon</a></li> <li><a href="/wiki/Claymore_mine" title="Claymore mine">M18A1 Claymore Mine</a></li> <li><a href="/wiki/M67_grenade" title="M67 grenade">M67 Fragmentation Grenade</a></li> <li><a href="/wiki/M72_LAW" title="M72 LAW">M72 Light Anti-tank Weapon (LAW)</a></li> <li><a href="/wiki/M79_grenade_launcher" title="M79 grenade launcher">M79 grenade launcher</a></li> <li><a href="/wiki/Mk_19_grenade_launcher" title="Mk 19 grenade launcher">MK-19 automatic grenade launcher</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color:#DCDCDC;color:inherit;text-align:center;"><a href="/wiki/Uniforms_of_the_United_States_Air_Force" title="Uniforms of the United States Air Force">Uniforms</a> and other equipment</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Airman_Battle_Uniform" title="Airman Battle Uniform">Airman Battle Uniform</a></li> <li><a href="/wiki/Army_Combat_Uniform" title="Army Combat Uniform">Army Combat Uniform</a></li> <li>Flight Suit</li> <li>Physical Training Uniform</li> <li>Service Dress Uniform</li> <li><a href="/wiki/Mess_dress" class="mw-redirect" title="Mess dress">Mess dress</a></li> <li><a href="/wiki/Personal_flotation_device" title="Personal flotation device">CMU – 33A/P22P-18</a></li></ul> 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rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239334494"></div><div role="navigation" class="navbox" aria-labelledby="United_States_Air_Force_system_numbers" style="padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:USAF_system_codes" title="Template:USAF system codes"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:USAF_system_codes" title="Template talk:USAF system codes"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:USAF_system_codes" title="Special:EditPage/Template:USAF system codes"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="United_States_Air_Force_system_numbers" style="font-size:114%;margin:0 4em"><a href="/wiki/United_States_Air_Force" title="United States Air Force">United States Air Force</a> system numbers</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">100–199</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Boeing_B-47_Stratojet" title="Boeing B-47 Stratojet">100</a></li> <li><a href="/wiki/Boeing_B-52_Stratofortress" title="Boeing B-52 Stratofortress">101</a> <ul><li><a href="/wiki/Pratt_%26_Whitney_JT3D" title="Pratt & Whitney JT3D">P</a></li></ul></li> <li><a href="/wiki/Convair_B-58_Hustler" title="Convair B-58 Hustler">102</a></li> <li><a href="/wiki/SM-62_Snark" title="SM-62 Snark">103</a></li> <li><a href="/wiki/SM-64_Navaho" title="SM-64 Navaho">104</a></li> <li><a href="/wiki/McDonnell_F-101_Voodoo" title="McDonnell F-101 Voodoo">105</a></li> <li>1061</li> <li>107 <ul><li><a href="/wiki/SM-65_Atlas" title="SM-65 Atlas">A-1</a></li> <li><a href="/wiki/SM-68_Titan" title="SM-68 Titan">A-2</a></li></ul></li> <li>1081</li> <li>1091</li> <li><a href="/wiki/North_American_XB-70_Valkyrie" title="North American XB-70 Valkyrie">110</a></li> <li>1111</li> <li><a href="/wiki/GAM-63_RASCAL" title="GAM-63 RASCAL">112</a></li> <li>1131</li> <li>1141</li> <li>1151</li> <li>1161</li> <li>117 <ul><li><a href="/w/index.php?title=Reconnaissance_Satellite_System&action=edit&redlink=1" class="new" title="Reconnaissance Satellite System (page does not exist)">L</a></li> <li><a href="/wiki/Samos_(satellite)" title="Samos (satellite)">M</a></li></ul></li> <li>118 <ul><li><a href="/wiki/LGM-118_Peacekeeper" title="LGM-118 Peacekeeper">A</a></li> <li><a href="/w/index.php?title=KA-27_(camera)&action=edit&redlink=1" class="new" title="KA-27 (camera) (page does not exist)">L</a></li> <li><a href="/w/index.php?title=Hypersonic_Reconnaissance_Manned_Boost-Glide_Rocket&action=edit&redlink=1" class="new" title="Hypersonic Reconnaissance Manned Boost-Glide Rocket (page does not exist)">P</a></li></ul></li> <li><a href="/wiki/Boeing_C-135_Stratolifter" title="Boeing C-135 Stratolifter">119</a> <ul><li><a href="/wiki/Pratt_%26_Whitney_JT3D" title="Pratt & Whitney JT3D">C/F</a></li> <li><a href="/wiki/CFM_International_CFM56" title="CFM International CFM56">E</a></li> <li><a href="/w/index.php?title=Strategic_Photo-Reconnaissance_Balloon_System&action=edit&redlink=1" class="new" title="Strategic Photo-Reconnaissance Balloon System (page does not exist)">L</a></li> <li><a href="/wiki/Boeing_EC-135" title="Boeing EC-135">T</a></li> <li><a href="/wiki/Boeing_KC-135_Stratotanker" title="Boeing KC-135 Stratotanker">Y</a></li></ul></li> <li><a href="/wiki/BGM-75_AICBM" title="BGM-75 AICBM">120</a></li> <li><a href="/wiki/GAM-67_Crossbow" title="GAM-67 Crossbow">121</a></li> <li><a href="/wiki/ADM-20_Quail" title="ADM-20 Quail">122</a></li> <li><a href="/wiki/XSM-73_Goose" title="XSM-73 Goose">123</a></li> <li><a href="/wiki/WS-124A_Flying_Cloud" title="WS-124A Flying Cloud">124</a></li> <li><a href="/wiki/WS-125" title="WS-125">125</a></li> <li><a href="/w/index.php?title=Bomber_Defense_Missile&action=edit&redlink=1" class="new" title="Bomber Defense Missile (page does not exist)">126</a></li> <li>1271</li> <li><a href="/w/index.php?title=WS-128A&action=edit&redlink=1" class="new" title="WS-128A (page does not exist)">128</a></li> <li><a href="/wiki/General_Dynamics_F-111_Aardvark" title="General Dynamics F-111 Aardvark">129</a></li> <li><a href="/w/index.php?title=WS-130A&action=edit&redlink=1" class="new" title="WS-130A (page does not exist)">130</a></li> <li><a href="/wiki/AGM-28_Hound_Dog" title="AGM-28 Hound Dog">131</a></li> <li>132 <ul><li><a href="/w/index.php?title=Bomber_Defense_Missile&action=edit&redlink=1" class="new" title="Bomber Defense Missile (page does not exist)">A</a></li> <li><a href="/w/index.php?title=WS-132B&action=edit&redlink=1" class="new" title="WS-132B (page does not exist)">B</a></li></ul></li> <li><a href="/wiki/LGM-30_Minuteman" title="LGM-30 Minuteman">133</a></li> <li>1341</li> <li><a href="/w/index.php?title=WS-135A&action=edit&redlink=1" class="new" title="WS-135A (page does not exist)">135</a></li> <li>1361</li> <li>1371</li> <li><a href="/wiki/GAM-87_Skybolt" title="GAM-87 Skybolt">138</a></li> <li><a href="/wiki/Rockwell_B-1_Lancer" title="Rockwell B-1 Lancer">139</a></li> <li><a href="/wiki/AGM-69_SRAM" title="AGM-69 SRAM">140</a></li> <li>1411</li> <li><a href="/wiki/Popeye_(missile)" title="Popeye (missile)">142</a></li> <li>143–1971</li> <li><a href="/w/index.php?title=WS-198A&action=edit&redlink=1" class="new" title="WS-198A (page does not exist)">198</a></li> <li><a href="/wiki/WS-199" title="WS-199">199</a> <ul><li><a href="/wiki/Bold_Orion" title="Bold Orion">B</a></li> <li><a href="/wiki/High_Virgo" title="High Virgo">C</a></li> <li><a href="/wiki/Alpha_Draco" title="Alpha Draco">D</a></li> <li><a href="/w/index.php?title=WS-199Y&action=edit&redlink=1" class="new" title="WS-199Y (page does not exist)">Y</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">200–299</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/CIM-10_Bomarc" title="CIM-10 Bomarc">200</a></li> <li>201 <ul><li><a href="/wiki/Convair_F-102_Delta_Dagger" title="Convair F-102 Delta Dagger">A/L</a></li> <li><a href="/wiki/Convair_F-106_Delta_Dart" title="Convair F-106 Delta Dart">B/W</a></li> <li><a href="/wiki/Pratt_%26_Whitney_J75" title="Pratt & Whitney J75">E</a></li></ul></li> <li><a href="/wiki/North_American_XF-108_Rapier" title="North American XF-108 Rapier">202</a></li> <li>2031</li> <li><a href="/wiki/Republic_XF-103" title="Republic XF-103">204</a></li> <li><a href="/wiki/Northrop_F-89_Scorpion" title="Northrop F-89 Scorpion">205</a></li> <li><a href="/wiki/North_American_F-86D_Sabre" title="North American F-86D Sabre">206</a></li> <li>2071</li> <li><a href="/wiki/AIM-26_Falcon" title="AIM-26 Falcon">208</a></li> <li>2091</li> <li><a href="/wiki/Samos_(satellite)" title="Samos (satellite)">210</a></li> <li>2111</li> <li><a href="/w/index.php?title=Air_Weapons_Control_System&action=edit&redlink=1" class="new" title="Air Weapons Control System (page does not exist)">212</a></li> <li><a href="/wiki/Distant_Early_Warning_Line" title="Distant Early Warning Line">213</a></li> <li><a href="/wiki/Lockheed_C-121_Constellation" title="Lockheed C-121 Constellation">214</a></li> <li>2151</li> <li><a href="/wiki/Semi-Automatic_Ground_Environment" title="Semi-Automatic Ground Environment">216</a></li> <li><a href="/wiki/McDonnell_F-101_Voodoo" title="McDonnell F-101 Voodoo">217</a></li> <li><a href="/wiki/RIM-8_Talos" title="RIM-8 Talos">218</a></li> <li>2191</li> <li><a href="/wiki/AIM-4_Falcon" title="AIM-4 Falcon">220</a></li> <li><a href="/wiki/AIM-9_Sidewinder" title="AIM-9 Sidewinder">221</a></li> <li>222 <ul><li><a href="/wiki/Project_Wizard" title="Project Wizard">A</a></li> <li><a href="/w/index.php?title=Advanced_Electro-Optical_Countermeasures&action=edit&redlink=1" class="new" title="Advanced Electro-Optical Countermeasures (page does not exist)">G</a></li></ul></li> <li>2231</li> <li><a href="/wiki/Nike_Zeus" title="Nike Zeus">224</a></li> <li>2251</li> <li><a href="/wiki/AIM-7_Sparrow" title="AIM-7 Sparrow">226</a></li> <li>227–2381</li> <li><a href="/wiki/Missile_Defense_Alarm_System" title="Missile Defense Alarm System">239</a></li> <li>240–2781</li> <li><a href="/wiki/Scout_(rocket_family)" title="Scout (rocket family)">279</a></li> <li>280–2981</li> <li><a href="/w/index.php?title=WS-299A&action=edit&redlink=1" class="new" title="WS-299A (page does not exist)">299</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">300–399</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Republic_F-105_Thunderchief" title="Republic F-105 Thunderchief">300</a></li> <li>3011</li> <li><a href="/wiki/Martin_XB-68" title="Martin XB-68">302</a></li> <li><a href="/wiki/Lockheed_F-104_Starfighter" title="Lockheed F-104 Starfighter">303</a></li> <li>3041</li> <li>3051</li> <li>306 <ul><li><a href="/wiki/Republic_F-105_Thunderchief" title="Republic F-105 Thunderchief">A/L</a></li> <li><a href="/wiki/North_American_F-107" title="North American F-107">B</a></li></ul></li> <li><a href="/wiki/Martin_B-57_Canberra" title="Martin B-57 Canberra">307</a></li> <li><a href="/wiki/Douglas_B-66_Destroyer" title="Douglas B-66 Destroyer">308</a></li> <li><a href="/wiki/MGM-13_Mace" title="MGM-13 Mace">309</a></li> <li>3101</li> <li>3111</li> <li>3121</li> <li>3131</li> <li><a href="/wiki/AGM-62_Walleye" title="AGM-62 Walleye">314</a></li> <li>315 <ul><li><a href="/wiki/PGM-17_Thor" title="PGM-17 Thor">A-1</a></li> <li><a href="/wiki/PGM-19_Jupiter" title="PGM-19 Jupiter">A-2</a></li></ul></li> <li><a href="/wiki/North_American_F-86_Sabre" title="North American F-86 Sabre">316</a></li> <li><a href="/w/index.php?title=Anti-Tank_Guided_Air_Rocket&action=edit&redlink=1" class="new" title="Anti-Tank Guided Air Rocket (page does not exist)">317</a></li> <li>3181</li> <li><a href="/wiki/AGM-65_Maverick" title="AGM-65 Maverick">319</a></li> <li>3201</li> <li><a href="/wiki/AGM-12_Bullpup" title="AGM-12 Bullpup">321</a></li> <li>3221</li> <li><a href="/w/index.php?title=Tactical_Strike/Reconnaissance_System&action=edit&redlink=1" class="new" title="Tactical Strike/Reconnaissance System (page does not exist)">323</a></li> <li><a href="/wiki/General_Dynamics_F-111_Aardvark" title="General Dynamics F-111 Aardvark">324</a> <ul><li><a href="/wiki/General_Dynamics%E2%80%93Grumman_EF-111A_Raven" title="General Dynamics–Grumman EF-111A Raven">L</a></li> <li><a href="/wiki/Pratt_%26_Whitney_TF30" title="Pratt & Whitney TF30">M/N</a></li></ul></li> <li><a href="/w/index.php?title=Mobile_Medium_Range_Ballistic_Missile&action=edit&redlink=1" class="new" title="Mobile Medium Range Ballistic Missile (page does not exist)">325</a></li> <li><a href="/wiki/McDonnell_Douglas_F-4_Phantom_II" title="McDonnell Douglas F-4 Phantom II">326</a></li> <li><a href="/wiki/McDonnell_Douglas_F-4_Phantom_II" title="McDonnell Douglas F-4 Phantom II">327</a> <ul><li><a href="/wiki/General_Electric_J79" title="General Electric J79">E</a></li></ul></li> <li><a href="/wiki/McDonnell_Douglas_F-15_Eagle" title="McDonnell Douglas F-15 Eagle">328</a> <ul><li><a href="/wiki/McDonnell_Douglas_F-15E_Strike_Eagle" title="McDonnell Douglas F-15E Strike Eagle">E</a></li></ul></li> <li><a href="/wiki/Fairchild_Republic_A-10_Thunderbolt_II" title="Fairchild Republic A-10 Thunderbolt II">329</a> <ul><li><a href="/wiki/General_Electric_TF34" title="General Electric TF34">F</a></li></ul></li> <li>3301</li> <li>3311</li> <li>3321</li> <li>3331</li> <li>3341</li> <li><a href="/wiki/Cessna_A-37_Dragonfly" title="Cessna A-37 Dragonfly">335</a></li> <li><a href="/wiki/North_American_Rockwell_OV-10_Bronco" title="North American Rockwell OV-10 Bronco">336</a></li> <li><a href="/wiki/LTV_A-7_Corsair_II" title="LTV A-7 Corsair II">337</a></li> <li>338–3791</li> <li>380 <ul><li><a href="/wiki/Pratt_%26_Whitney_F100" title="Pratt & Whitney F100">A/B/E/F/N</a></li> <li><a href="/wiki/General_Electric_F110" title="General Electric F110">P</a></li></ul></li> <li>381–3971</li> <li><a href="/w/index.php?title=Theater_Ballistic_Missile&action=edit&redlink=1" class="new" title="Theater Ballistic Missile (page does not exist)">398</a></li> <li>399 <ul><li><a href="/w/index.php?title=WS-399A&action=edit&redlink=1" class="new" title="WS-399A (page does not exist)">A</a></li> <li><a href="/w/index.php?title=WS-399B&action=edit&redlink=1" class="new" title="WS-399B (page does not exist)">B</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">400–499</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Lockheed_C-130_Hercules" title="Lockheed C-130 Hercules">400</a> <ul><li><a href="/wiki/Lockheed_AC-130" title="Lockheed AC-130">B/C/N</a></li> <li><a href="/wiki/Allison_T56" title="Allison T56">E</a></li> <li><a href="/wiki/Lockheed_MC-130" title="Lockheed MC-130">G/H</a></li> <li><a href="/wiki/Lockheed_RC-130_Hercules" title="Lockheed RC-130 Hercules">M</a></li></ul></li> <li><a href="/wiki/Douglas_C-132" title="Douglas C-132">401</a></li> <li><a href="/wiki/Douglas_C-133_Cargomaster" title="Douglas C-133 Cargomaster">402</a></li> <li>4031</li> <li><a href="/w/index.php?title=Air_Traffic_Control_And_Landing_System&action=edit&redlink=1" class="new" title="Air Traffic Control And Landing System (page does not exist)">404</a></li> <li>405 <ul><li><a href="/w/index.php?title=Spaceborne_Laser_Communications_System&action=edit&redlink=1" class="new" title="Spaceborne Laser Communications System (page does not exist)">B</a></li></ul></li> <li><a href="/w/index.php?title=System_405C&action=edit&redlink=1" class="new" title="System 405C (page does not exist)">C</a></li> <li><a href="/w/index.php?title=System_405D&action=edit&redlink=1" class="new" title="System 405D (page does not exist)">D</a></li> <li>4061</li> <li><a href="/w/index.php?title=Ground_Theater_Air_Control_System&action=edit&redlink=1" class="new" title="Ground Theater Air Control System (page does not exist)">407</a></li> <li>4081</li> <li>4091</li> <li><a href="/wiki/Lockheed_C-5_Galaxy" title="Lockheed C-5 Galaxy">410</a> <ul><li><a href="/wiki/General_Electric_TF39" title="General Electric TF39">E</a></li> <li><a href="/w/index.php?title=Area_Surveillance_Control_System&action=edit&redlink=1" class="new" title="Area Surveillance Control System (page does not exist)">L</a></li></ul></li> <li><a href="/wiki/Boeing_E-3_Sentry" title="Boeing E-3 Sentry">411</a> <ul><li><a href="/wiki/Pratt_%26_Whitney_JT3D" title="Pratt & Whitney JT3D">E</a></li> <li><a href="/wiki/Airborne_Warning_And_Control_System" class="mw-redirect" title="Airborne Warning And Control System">L</a></li></ul></li> <li><a href="/w/index.php?title=Air_Weapons_Control_System&action=edit&redlink=1" class="new" title="Air Weapons Control System (page does not exist)">412</a></li> <li><a href="/wiki/Distant_Early_Warning_Line" title="Distant Early Warning Line">413</a></li> <li>414 <ul><li><a href="/w/index.php?title=Atmospheric_Early_Warning_System&action=edit&redlink=1" class="new" title="Atmospheric Early Warning System (page does not exist)">L</a></li> <li><a href="/w/index.php?title=SS-414M&action=edit&redlink=1" class="new" title="SS-414M (page does not exist)">M</a></li></ul></li> <li><a href="/w/index.php?title=Military_Airlift_Command_Integrated_Management_System&action=edit&redlink=1" class="new" title="Military Airlift Command Integrated Management System (page does not exist)">415</a></li> <li>416 <ul><li><a href="/wiki/Semi-Automatic_Ground_Environment" title="Semi-Automatic Ground Environment">L</a></li> <li><a href="/wiki/Back-Up_Interceptor_Control" title="Back-Up Interceptor Control">M (I)</a></li> <li><a href="/w/index.php?title=White_Sands_Missile_Range_Surveillance_System&action=edit&redlink=1" class="new" title="White Sands Missile Range Surveillance System (page does not exist)">M (II)</a></li> <li><a href="/w/index.php?title=Seek_Dawn&action=edit&redlink=1" class="new" title="Seek Dawn (page does not exist)">P</a></li> <li><a href="/w/index.php?title=Common_Digitizer&action=edit&redlink=1" class="new" title="Common Digitizer (page does not exist)">Q</a></li></ul></li> <li><a href="/w/index.php?title=SS-417L&action=edit&redlink=1" class="new" title="SS-417L (page does not exist)">417</a></li> <li>418 <ul><li><a href="/w/index.php?title=Ryukyu_Air_Defense_System&action=edit&redlink=1" class="new" title="Ryukyu Air Defense System (page does not exist)">L</a></li> <li><a href="/w/index.php?title=Hawaiian_Air_Defense_System&action=edit&redlink=1" class="new" title="Hawaiian Air Defense System (page does not exist)">M</a></li></ul></li> <li>4191</li> <li><a href="/wiki/Northrop_F-5" title="Northrop F-5">420</a> <ul><li><a href="/wiki/Northrop_T-38_Talon" title="Northrop T-38 Talon">L/W</a></li></ul></li> <li>4211</li> <li><a href="/wiki/Boeing_KC-135_Stratotanker" title="Boeing KC-135 Stratotanker">422</a></li> <li><a href="/wiki/Automatic_Digital_Network" title="Automatic Digital Network">423</a></li> <li><a href="/wiki/Cessna_T-37_Tweet" title="Cessna T-37 Tweet">424</a></li> <li><a href="/wiki/Cheyenne_Mountain_Complex" title="Cheyenne Mountain Complex">425</a></li> <li>426 <ul><li><a href="/wiki/Northrop_AQM-35" title="Northrop AQM-35">L</a></li> <li><a href="/w/index.php?title=SS-426M&action=edit&redlink=1" class="new" title="SS-426M (page does not exist)">M</a></li></ul></li> <li>427 <ul><li><a href="/wiki/Lockheed_AQM-60_Kingfisher" title="Lockheed AQM-60 Kingfisher">L</a></li> <li><a href="/w/index.php?title=Military_Airlift_Command_Integrated_Management_System&action=edit&redlink=1" class="new" title="Military Airlift Command Integrated Management System (page does not exist)">M</a></li></ul></li> <li>428 <ul><li><a href="/w/index.php?title=Marine_Air_Ground_Intelligence_System&action=edit&redlink=1" class="new" title="Marine Air Ground Intelligence System (page does not exist)">A</a></li> <li><a href="/wiki/AN/URC-117_Ground_Wave_Emergency_Network" title="AN/URC-117 Ground Wave Emergency Network">L</a></li></ul></li> <li><a href="/wiki/Ryan_Firebee" title="Ryan Firebee">429</a></li> <li><a href="/w/index.php?title=Photographic_Processing_and_Interpretation_Facility&action=edit&redlink=1" class="new" title="Photographic Processing and Interpretation Facility (page does not exist)">430</a></li> <li>431 <ul><li><a href="/w/index.php?title=System_431G&action=edit&redlink=1" class="new" title="System 431G (page does not exist)">G (I)</a></li> <li><a href="/w/index.php?title=Traffic_Control_And_Landing_System&action=edit&redlink=1" class="new" title="Traffic Control And Landing System (page does not exist)">G (II)</a></li></ul></li> <li><a href="/w/index.php?title=Crash_Locator_System&action=edit&redlink=1" class="new" title="Crash Locator System (page does not exist)">432</a></li> <li><a href="/w/index.php?title=METRO_Weather_Observation_and_Forecasting_System&action=edit&redlink=1" class="new" title="METRO Weather Observation and Forecasting System (page does not exist)">433</a></li> <li><a href="/wiki/Air_Force_Space_Surveillance_System" title="Air Force Space Surveillance System">434</a></li> <li>435 <ul><li><a href="/w/index.php?title=Navy_Navigational_Satellite_System&action=edit&redlink=1" class="new" title="Navy Navigational Satellite System (page does not exist)">A</a></li> <li><a href="/wiki/Boeing_EC-135" title="Boeing EC-135">L</a></li></ul></li> <li><a href="/wiki/Strategic_Automated_Command_and_Control_System" title="Strategic Automated Command and Control System">436</a></li> <li><a href="/w/index.php?title=Nuclear-Armed_Unguided_Satellite_Inspection_System&action=edit&redlink=1" class="new" title="Nuclear-Armed Unguided Satellite Inspection System (page does not exist)">437</a></li> <li><a href="/w/index.php?title=AIDS_Intelligence_Data_Handling_System&action=edit&redlink=1" class="new" title="AIDS Intelligence Data Handling System (page does not exist)">438</a></li> <li><a href="/w/index.php?title=Sea_Coastal_Cable_Communications_System&action=edit&redlink=1" class="new" title="Sea Coastal Cable Communications System (page does not exist)">439</a></li> <li><a href="/w/index.php?title=Forward_Scatter_Over-the-Horizon_Radar_System&action=edit&redlink=1" class="new" title="Forward Scatter Over-the-Horizon Radar System (page does not exist)">440</a></li> <li>441 <ul><li><a href="/wiki/Cobra_Mist" title="Cobra Mist">A</a></li> <li><a href="/w/index.php?title=Cobra_Talon&action=edit&redlink=1" class="new" title="Cobra Talon (page does not exist)">D</a></li> <li><a href="/wiki/Air_Force_Satellite_Communications" title="Air Force Satellite Communications">L</a></li></ul></li> <li><a href="/wiki/Lockheed_X-7" title="Lockheed X-7">442</a></li> <li><a href="/wiki/Bell_UH-1_Iroquois" title="Bell UH-1 Iroquois">443</a></li> <li>4441</li> <li>445 <ul><li><a href="/w/index.php?title=SS-445L&action=edit&redlink=1" class="new" title="SS-445L (page does not exist)">L</a></li> <li><a href="/w/index.php?title=SS-445M&action=edit&redlink=1" class="new" title="SS-445M (page does not exist)">M</a></li></ul></li> <li><a href="/wiki/De_Havilland_Canada_DHC-4_Caribou" title="De Havilland Canada DHC-4 Caribou">446</a></li> <li><a href="/wiki/North_American_X-15" title="North American X-15">447</a></li> <li>4481</li> <li>4491</li> <li><a href="/wiki/LORAN" title="LORAN">450</a></li> <li>451 <ul><li><a href="/w/index.php?title=Spain_Air_Defense_System&action=edit&redlink=1" class="new" title="Spain Air Defense System (page does not exist)">D</a></li> <li><a href="/wiki/Joint_Tactical_Information_Distribution_System" title="Joint Tactical Information Distribution System">L</a></li></ul></li> <li><a href="/wiki/North_American_Sabreliner" title="North American Sabreliner">452</a></li> <li><a href="/wiki/Avro_Canada_VZ-9_Avrocar" title="Avro Canada VZ-9 Avrocar">453</a></li> <li>4541</li> <li><a href="/w/index.php?title=HYWARDS&action=edit&redlink=1" class="new" title="HYWARDS (page does not exist)">455</a></li> <li><a href="/w/index.php?title=Quadrajector&action=edit&redlink=1" class="new" title="Quadrajector (page does not exist)">456</a></li> <li>4571</li> <li><a href="/w/index.php?title=Wideband_Transmission_System&action=edit&redlink=1" class="new" title="Wideband Transmission System (page does not exist)">458</a></li> <li><a href="/w/index.php?title=RS-459L&action=edit&redlink=1" class="new" title="RS-459L (page does not exist)">459</a></li> <li><a href="/wiki/Northrop_Grumman_E-8_Joint_STARS" title="Northrop Grumman E-8 Joint STARS">460</a> <ul><li><a href="/wiki/Boeing_WC-135_Constant_Phoenix" title="Boeing WC-135 Constant Phoenix">L</a></li></ul></li> <li><a href="/w/index.php?title=High-Altitude_Balloon_Reconnaissance_System&action=edit&redlink=1" class="new" title="High-Altitude Balloon Reconnaissance System (page does not exist)">461</a></li> <li><a href="/wiki/Beechcraft_AQM-37_Jayhawk" title="Beechcraft AQM-37 Jayhawk">462</a></li> <li><a href="/wiki/463L_master_pallet" title="463L master pallet">463</a></li> <li><a href="/wiki/Boeing_X-20_Dyna-Soar" title="Boeing X-20 Dyna-Soar">464</a></li> <li><a href="/wiki/ITT_465L_Strategic_Air_Command_Control_System" title="ITT 465L Strategic Air Command Control System">465</a></li> <li><a href="/w/index.php?title=466L_Electromagnetic_Intelligence_System&action=edit&redlink=1" class="new" title="466L Electromagnetic Intelligence System (page does not exist)">466</a></li> <li><a href="/w/index.php?title=Advanced_Navigational_Training_Support_System&action=edit&redlink=1" class="new" title="Advanced Navigational Training Support System (page does not exist)">467</a></li> <li><a href="/wiki/Lockheed_JetStar" title="Lockheed JetStar">468</a></li> <li><a href="/w/index.php?title=Conversion_Of_Range_Telemetry_Systems&action=edit&redlink=1" class="new" title="Conversion Of Range Telemetry Systems (page does not exist)">469</a></li> <li><a href="/w/index.php?title=System_470L&action=edit&redlink=1" class="new" title="System 470L (page does not exist)">470</a></li> <li>471 <ul><li><a href="/wiki/Boeing_Vertol_CH-46_Sea_Knight" title="Boeing Vertol CH-46 Sea Knight">L (I)</a></li> <li><a href="/wiki/Boeing_CH-47_Chinook" title="Boeing CH-47 Chinook">L (II)</a></li></ul></li> <li><a href="/w/index.php?title=Support_System_Test_Aircraft&action=edit&redlink=1" class="new" title="Support System Test Aircraft (page does not exist)">472</a></li> <li><a href="/w/index.php?title=USAF_Command_and_Control_System&action=edit&redlink=1" class="new" title="USAF Command and Control System (page does not exist)">473</a></li> <li>474 <ul><li><a href="/wiki/Ballistic_Missile_Early_Warning_System" title="Ballistic Missile Early Warning System">L</a></li> <li><a href="/wiki/AN/FPS-26_Radar" title="AN/FPS-26 Radar">N</a></li></ul></li> <li>4751</li> <li><a href="/wiki/Lockheed_C-141_Starlifter" title="Lockheed C-141 Starlifter">476</a> <ul><li><a href="/wiki/Pratt_%26_Whitney_JT3D" title="Pratt & Whitney JT3D">E</a></li></ul></li> <li><a href="/wiki/GE_477L_Nuclear_Detection_and_Reporting_System" title="GE 477L Nuclear Detection and Reporting System">477</a></li> <li>478 <ul><li><a href="/wiki/LTV_XC-142" title="LTV XC-142">A</a></li> <li><a href="/w/index.php?title=Tri-Service_Tactical_Communications_System&action=edit&redlink=1" class="new" title="Tri-Service Tactical Communications System (page does not exist)">T</a></li></ul></li> <li>4791</li> <li><a href="/w/index.php?title=SS-480L&action=edit&redlink=1" class="new" title="SS-480L (page does not exist)">480</a></li> <li><a href="/wiki/Boeing_E-4" title="Boeing E-4">481</a> <ul><li><a href="/wiki/Post-Attack_Command_and_Control_System" title="Post-Attack Command and Control System">L</a></li></ul></li> <li><a href="/wiki/Sikorsky_CH-53_Sea_Stallion" title="Sikorsky CH-53 Sea Stallion">482</a> <ul><li><a href="/wiki/General_Electric_T64" title="General Electric T64">E</a></li> <li><a href="/w/index.php?title=Ground_Theater_Air_Control_System&action=edit&redlink=1" class="new" title="Ground Theater Air Control System (page does not exist)">L</a></li> <li><a href="/wiki/Sikorsky_MH-53" title="Sikorsky MH-53">M/Z</a></li></ul></li> <li><a href="/w/index.php?title=Air/Ground_Digital_Secure_Teletype_Communication_System&action=edit&redlink=1" class="new" title="Air/Ground Digital Secure Teletype Communication System (page does not exist)">483</a></li> <li>484 <ul><li><a href="/w/index.php?title=High_Frequency_Global_Communication_System&action=edit&redlink=1" class="new" title="High Frequency Global Communication System (page does not exist)">L</a></li> <li><a href="/w/index.php?title=Build_Back&action=edit&redlink=1" class="new" title="Build Back (page does not exist)">M</a></li> <li><a href="/w/index.php?title=Wet_Wash&action=edit&redlink=1" class="new" title="Wet Wash (page does not exist)">N</a></li></ul></li> <li>485 <ul><li><a href="/w/index.php?title=Ground_Theater_Air_Control_System&action=edit&redlink=1" class="new" title="Ground Theater Air Control System (page does not exist)">L</a></li> <li><a href="/wiki/Sikorsky_S-61R" title="Sikorsky S-61R">Z</a></li></ul></li> <li><a href="/w/index.php?title=Mediterranean_Communications_System&action=edit&redlink=1" class="new" title="Mediterranean Communications System (page does not exist)">486</a></li> <li><a href="/wiki/Survivable_Low_Frequency_Communications_System" title="Survivable Low Frequency Communications System">487</a></li> <li><a href="/wiki/Green_Pine_(communications)" title="Green Pine (communications)">488</a></li> <li><a href="/w/index.php?title=Northern_Area_Command_System&action=edit&redlink=1" class="new" title="Northern Area Command System (page does not exist)">489</a></li> <li>490 <ul><li><a href="/w/index.php?title=Automatic_Voice_Network_of_the_Defense_Communications_System&action=edit&redlink=1" class="new" title="Automatic Voice Network of the Defense Communications System (page does not exist)">L</a></li> <li><a href="/w/index.php?title=Post_Attack_Intercontinental_Link&action=edit&redlink=1" class="new" title="Post Attack Intercontinental Link (page does not exist)">M</a></li></ul></li> <li>4911</li> <li><a href="/w/index.php?title=United_States_Strike_Command_and_Control&action=edit&redlink=1" class="new" title="United States Strike Command and Control (page does not exist)">492</a></li> <li><a href="/wiki/Automatic_Secure_Voice_Communications_Network" title="Automatic Secure Voice Communications Network">493</a></li> <li><a href="/wiki/AN/DRC-8_Emergency_Rocket_Communications_System" title="AN/DRC-8 Emergency Rocket Communications System">494</a></li> <li>495 <ul><li><a href="/w/index.php?title=IFF_Mark_XII&action=edit&redlink=1" class="new" title="IFF Mark XII (page does not exist)">L (I)</a></li> <li><a href="/w/index.php?title=Command_and_Control_Information_Processing_System&action=edit&redlink=1" class="new" title="Command and Control Information Processing System (page does not exist)">L (II)</a></li></ul></li> <li><a href="/wiki/United_States_Space_Surveillance_Network" title="United States Space Surveillance Network">496</a></li> <li>497 <ul><li><a href="/w/index.php?title=SS-497A&action=edit&redlink=1" class="new" title="SS-497A (page does not exist)">A</a></li> <li><a href="/w/index.php?title=Automatic_Digital_Switching_System&action=edit&redlink=1" class="new" title="Automatic Digital Switching System (page does not exist)">L (I)</a></li> <li><a href="/wiki/United_States_national_missile_defense" title="United States national missile defense">L</a></li></ul></li> <li>498 <ul><li><a href="/w/index.php?title=SS-498A&action=edit&redlink=1" class="new" title="SS-498A (page does not exist)">A</a></li> <li><a href="/wiki/Lockheed_C-130_Hercules" title="Lockheed C-130 Hercules">C</a></li> <li><a href="/w/index.php?title=Strategic_Communications_System&action=edit&redlink=1" class="new" title="Strategic Communications System (page does not exist)">D</a></li> <li><a href="/wiki/Military_Air_Transport_Service" title="Military Air Transport Service">E</a></li> <li><a href="/wiki/Milstar" title="Milstar">L</a></li></ul></li> <li>499 <ul><li><a href="/w/index.php?title=SS-499A&action=edit&redlink=1" class="new" title="SS-499A (page does not exist)">A</a></li> <li><a href="/w/index.php?title=SS-499C&action=edit&redlink=1" class="new" title="SS-499C (page does not exist)">C</a></li> <li><a href="/w/index.php?title=SS-499D&action=edit&redlink=1" class="new" title="SS-499D (page does not exist)">D</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">500–599</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/w/index.php?title=Ground_Communication_Product_Group&action=edit&redlink=1" class="new" title="Ground Communication Product Group (page does not exist)">500</a></li> <li>501–5191</li> <li><a href="/w/index.php?title=OS-520B&action=edit&redlink=1" class="new" title="OS-520B (page does not exist)">520</a></li> <li>521–5291</li> <li><a href="/w/index.php?title=OS-530A&action=edit&redlink=1" class="new" title="OS-530A (page does not exist)">530</a></li> <li>531–5411</li> <li><a href="/w/index.php?title=System_542N&action=edit&redlink=1" class="new" title="System 542N (page does not exist)">542</a></li> <li>543–5491</li> <li>550 <ul><li><a href="/w/index.php?title=OS-550A&action=edit&redlink=1" class="new" title="OS-550A (page does not exist)">A</a></li> <li><a href="/w/index.php?title=OS-550E&action=edit&redlink=1" class="new" title="OS-550E (page does not exist)">E</a></li></ul></li> <li>551–5591</li> <li>560 <ul><li><a href="/w/index.php?title=OS-560A&action=edit&redlink=1" class="new" title="OS-560A (page does not exist)">A</a></li> <li><a href="/w/index.php?title=OS-560F&action=edit&redlink=1" class="new" title="OS-560F (page does not exist)">F</a></li></ul></li> <li>561–5691</li> <li><a href="/w/index.php?title=OS-570A&action=edit&redlink=1" class="new" title="OS-570A (page does not exist)">570</a></li> <li>571–5791</li> <li>580 <ul><li><a href="/w/index.php?title=OS-580A&action=edit&redlink=1" class="new" title="OS-580A (page does not exist)">A</a></li> <li><a href="/w/index.php?title=OS-580E&action=edit&redlink=1" class="new" title="OS-580E (page does not exist)">E</a></li></ul></li> <li>581–5891</li> <li><a href="/w/index.php?title=System_590K&action=edit&redlink=1" class="new" title="System 590K (page does not exist)">590</a></li> <li><a href="/wiki/GBU-15" title="GBU-15">591</a></li> <li><a href="/w/index.php?title=System_592K&action=edit&redlink=1" class="new" title="System 592K (page does not exist)">592</a></li> <li>593–5991</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">600–699</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/w/index.php?title=RS-600A&action=edit&redlink=1" class="new" title="RS-600A (page does not exist)">600</a></li> <li>601 <ul><li><a href="/wiki/Lockheed_X-7" title="Lockheed X-7">A</a></li> <li><a href="/w/index.php?title=Advanced_Aerospace_Offensive_System&action=edit&redlink=1" class="new" title="Advanced Aerospace Offensive System (page does not exist)">L</a></li></ul></li> <li>602 <ul><li><a href="/wiki/Bell_XV-3" title="Bell XV-3">A</a></li> <li><a href="/w/index.php?title=Advanced_Aerospace_Defensive_System&action=edit&redlink=1" class="new" title="Advanced Aerospace Defensive System (page does not exist)">L</a></li></ul></li> <li>603 <ul><li><a href="/wiki/Ryan_X-13_Vertijet" title="Ryan X-13 Vertijet">A</a></li> <li><a href="/w/index.php?title=Tactical_Forces_System&action=edit&redlink=1" class="new" title="Tactical Forces System (page does not exist)">L</a></li></ul></li> <li><a href="/w/index.php?title=RS-604A&action=edit&redlink=1" class="new" title="RS-604A (page does not exist)">604</a></li> <li><a href="/wiki/North_American_X-15" title="North American X-15">605</a></li> <li><a href="/wiki/Avro_Canada_VZ-9_Avrocar" title="Avro Canada VZ-9 Avrocar">606</a></li> <li><a href="/wiki/Hiller_X-18" title="Hiller X-18">607</a></li> <li>6081</li> <li><a href="/wiki/Scout_(rocket_family)" title="Scout (rocket family)">609</a></li> <li>6101</li> <li>6111</li> <li>6121</li> <li>6131</li> <li><a href="/w/index.php?title=RS-614A&action=edit&redlink=1" class="new" title="RS-614A (page does not exist)">614</a></li> <li>6151</li> <li><a href="/wiki/Minimum_Essential_Emergency_Communications_Network" title="Minimum Essential Emergency Communications Network">616</a></li> <li>6171</li> <li><a href="/w/index.php?title=RS-618A&action=edit&redlink=1" class="new" title="RS-618A (page does not exist)">618</a></li> <li>6191</li> <li><a href="/wiki/Boeing_X-20_Dyna-Soar" title="Boeing X-20 Dyna-Soar">620</a></li> <li>621 <ul><li><a href="/wiki/Project_SAINT" title="Project SAINT">A/B (I)</a></li> <li><a href="/w/index.php?title=Integrated_NavSat/Inertial_Test_System&action=edit&redlink=1" class="new" title="Integrated NavSat/Inertial Test System (page does not exist)">B (II)</a></li></ul></li> <li><a href="/wiki/CORONA_(satellite)" title="CORONA (satellite)">622</a></li> <li><a href="/w/index.php?title=Large_Solid-Propellant_Launch_Vehicle_Rocket_Motor&action=edit&redlink=1" class="new" title="Large Solid-Propellant Launch Vehicle Rocket Motor (page does not exist)">623</a></li> <li><a href="/wiki/Titan_(rocket_family)" title="Titan (rocket family)">624</a></li> <li><a href="/w/index.php?title=RS-625A&action=edit&redlink=1" class="new" title="RS-625A (page does not exist)">625</a></li> <li>6261</li> <li><a href="/w/index.php?title=Advanced_Ballistic_Reentry_System&action=edit&redlink=1" class="new" title="Advanced Ballistic Reentry System (page does not exist)">627</a></li> <li>6281</li> <li>6291</li> <li>6301</li> <li>6311</li> <li><a href="/w/index.php?title=AN/AAR-44&action=edit&redlink=1" class="new" title="AN/AAR-44 (page does not exist)">632</a></li> <li><a href="/w/index.php?title=Stellar_Inertial_Doppler_System&action=edit&redlink=1" class="new" title="Stellar Inertial Doppler System (page does not exist)">633</a></li> <li>634 <ul><li><a href="/wiki/Cobra_Dane" title="Cobra Dane">A</a></li> <li><a href="/wiki/Joint_Tactical_Information_Distribution_System" title="Joint Tactical Information Distribution System">B</a></li></ul></li> <li><a href="/w/index.php?title=AN/ALE-24&action=edit&redlink=1" class="new" title="AN/ALE-24 (page does not exist)">635</a></li> <li>6361</li> <li>6371</li> <li><a href="/wiki/GAM-87_Skybolt" title="GAM-87 Skybolt">638</a></li> <li><a href="/w/index.php?title=AN/ALE-40&action=edit&redlink=1" class="new" title="AN/ALE-40 (page does not exist)">639</a></li> <li><a href="/w/index.php?title=AN/ALE-45&action=edit&redlink=1" class="new" title="AN/ALE-45 (page does not exist)">640</a></li> <li><a href="/wiki/AN/ALE-47" title="AN/ALE-47">641</a></li> <li><a href="/w/index.php?title=Seek_Point&action=edit&redlink=1" class="new" title="Seek Point (page does not exist)">642</a></li> <li><a href="/w/index.php?title=AN/ALQ-184&action=edit&redlink=1" class="new" title="AN/ALQ-184 (page does not exist)">643</a></li> <li>6441</li> <li>6451</li> <li>6461</li> <li>6471</li> <li>648 <ul><li><a href="/wiki/RM-81_Agena" title="RM-81 Agena">A</a></li> <li><a href="/w/index.php?title=System_648D&action=edit&redlink=1" class="new" title="System 648D (page does not exist)">D</a></li> <li><a href="/wiki/AN/ALQ-99" title="AN/ALQ-99">P</a></li></ul></li> <li>649 <ul><li><a href="/w/index.php?title=RS-649A&action=edit&redlink=1" class="new" title="RS-649A (page does not exist)">A</a></li> <li><a href="/w/index.php?title=RS-649B&action=edit&redlink=1" class="new" title="RS-649B (page does not exist)">B</a></li> <li><a href="/w/index.php?title=WS-649C&action=edit&redlink=1" class="new" title="WS-649C (page does not exist)">C</a></li> <li><a href="/w/index.php?title=RS-649D&action=edit&redlink=1" class="new" title="RS-649D (page does not exist)">D</a></li> <li><a href="/w/index.php?title=Space_Counterweapons_System&action=edit&redlink=1" class="new" title="Space Counterweapons System (page does not exist)">E</a></li> <li><a href="/w/index.php?title=Satellite_Inspection_System&action=edit&redlink=1" class="new" title="Satellite Inspection System (page does not exist)">F</a></li> <li><a href="/w/index.php?title=Space_Combat_Weapon_System&action=edit&redlink=1" class="new" title="Space Combat Weapon System (page does not exist)">L</a></li> <li><a href="/wiki/Dash_10" class="mw-redirect" title="Dash 10">P</a></li></ul></li> <li><a href="/w/index.php?title=RS-650A&action=edit&redlink=1" class="new" title="RS-650A (page does not exist)">650</a></li> <li><a href="/w/index.php?title=System_651A&action=edit&redlink=1" class="new" title="System 651A (page does not exist)">651</a></li> <li><a href="/w/index.php?title=AN/ALQ-122&action=edit&redlink=1" class="new" title="AN/ALQ-122 (page does not exist)">652</a></li> <li>6531</li> <li>6541</li> <li>655 <ul><li><a href="/w/index.php?title=RS-655A&action=edit&redlink=1" class="new" title="RS-655A (page does not exist)">A (I)</a></li> <li><a href="/w/index.php?title=Low_Altutude_Short_Range_Missile&action=edit&redlink=1" class="new" title="Low Altutude Short Range Missile (page does not exist)">A (II)</a></li> <li><a href="/w/index.php?title=AN/ALQ-131&action=edit&redlink=1" class="new" title="AN/ALQ-131 (page does not exist)">P</a></li></ul></li> <li><a href="/wiki/AN/ALQ-135" title="AN/ALQ-135">656</a></li> <li>6571</li> <li>6581</li> <li>6591</li> <li><a href="/w/index.php?title=AN/ALQ-155&action=edit&redlink=1" class="new" title="AN/ALQ-155 (page does not exist)">660</a></li> <li><a href="/w/index.php?title=AN/ALQ-161&action=edit&redlink=1" class="new" title="AN/ALQ-161 (page does not exist)">661</a></li> <li>6621</li> <li>6631</li> <li><a href="/w/index.php?title=AN/ALQ-172&action=edit&redlink=1" class="new" title="AN/ALQ-172 (page does not exist)">664</a></li> <li>665 <ul><li><a href="/w/index.php?title=RS-665A&action=edit&redlink=1" class="new" title="RS-665A (page does not exist)">A (I)</a></li> <li><a href="/w/index.php?title=Multi-Sensor_Airborne_Reconnaissance/Strike_System&action=edit&redlink=1" class="new" title="Multi-Sensor Airborne Reconnaissance/Strike System (page does not exist)">A (II)</a></li></ul></li> <li>666 <ul><li><a href="/w/index.php?title=Integrated_NavSat/Inertial_Test_System&action=edit&redlink=1" class="new" title="Integrated NavSat/Inertial Test System (page does not exist)">A</a></li> <li><a href="/w/index.php?title=AN/ALQ-184&action=edit&redlink=1" class="new" title="AN/ALQ-184 (page does not exist)">C/P</a></li></ul></li> <li><a href="/w/index.php?title=System_667A&action=edit&redlink=1" class="new" title="System 667A (page does not exist)">667</a></li> <li><a href="/w/index.php?title=System_668A&action=edit&redlink=1" class="new" title="System 668A (page does not exist)">668</a></li> <li>6691</li> <li><a href="/w/index.php?title=System_670B&action=edit&redlink=1" class="new" title="System 670B (page does not exist)">670</a></li> <li>6711</li> <li>672 <ul><li><a href="/w/index.php?title=Advanced_ICBM_Technology_Program&action=edit&redlink=1" class="new" title="Advanced ICBM Technology Program (page does not exist)">A</a></li> <li><a href="/w/index.php?title=AN/ALR-56&action=edit&redlink=1" class="new" title="AN/ALR-56 (page does not exist)">M/P</a></li></ul></li> <li>6731</li> <li><a href="/w/index.php?title=AN/ALR-69&action=edit&redlink=1" class="new" title="AN/ALR-69 (page does not exist)">674</a></li> <li><a href="/w/index.php?title=RS-675A&action=edit&redlink=1" class="new" title="RS-675A (page does not exist)">675</a></li> <li>6761</li> <li>6771</li> <li>6781</li> <li><a href="/w/index.php?title=System_679A&action=edit&redlink=1" class="new" title="System 679A (page does not exist)">679</a></li> <li><a href="/w/index.php?title=Survivable_Flight_Control_System&action=edit&redlink=1" class="new" title="Survivable Flight Control System (page does not exist)">680</a></li> <li>681 <ul><li><a href="/w/index.php?title=System_681D&action=edit&redlink=1" class="new" title="System 681D (page does not exist)">D</a></li> <li><a href="/w/index.php?title=Base_Installation_Security_System&action=edit&redlink=1" class="new" title="Base Installation Security System (page does not exist)">E</a></li></ul></li> <li>6821</li> <li>683 <ul><li><a href="/wiki/Vela_(satellite)" title="Vela (satellite)">A</a></li> <li><a href="/w/index.php?title=Tactical_Air_Control_System&action=edit&redlink=1" class="new" title="Tactical Air Control System (page does not exist)">J</a></li> <li><a href="/wiki/Boeing_T-43" title="Boeing T-43">V</a></li></ul></li> <li>6841</li> <li><a href="/w/index.php?title=RS-685A&action=edit&redlink=1" class="new" title="RS-685A (page does not exist)">685</a></li> <li><a href="/w/index.php?title=Aircraft_Flight_Simulation_Complex&action=edit&redlink=1" class="new" title="Aircraft Flight Simulation Complex (page does not exist)">686</a></li> <li>687 <ul><li><a href="/w/index.php?title=TACSATCOM&action=edit&redlink=1" class="new" title="TACSATCOM (page does not exist)">J</a></li> <li><a href="/wiki/General_Dynamics_F-16_Fighting_Falcon" title="General Dynamics F-16 Fighting Falcon">P</a></li></ul></li> <li>6881</li> <li>6891</li> <li><a href="/w/index.php?title=System_690K&action=edit&redlink=1" class="new" title="System 690K (page does not exist)">690</a></li> <li>691 <ul><li><a href="/wiki/AGM-86_ALCM" title="AGM-86 ALCM">C</a></li> <li><a href="/w/index.php?title=System_691X&action=edit&redlink=1" class="new" title="System 691X (page does not exist)">X</a></li> <li><a href="/wiki/Worldwide_Military_Command_and_Control_System" title="Worldwide Military Command and Control System">Z</a></li></ul></li> <li>6921</li> <li><a href="/wiki/Ryan_X-13_Vertijet" title="Ryan X-13 Vertijet">693</a></li> <li>6941</li> <li>695 <ul><li><a href="/wiki/RAND_Corporation" title="RAND Corporation">A</a></li> <li><a href="/wiki/ANSER" title="ANSER">B</a></li> <li><a href="/wiki/Itek" title="Itek">C</a></li> <li><a href="/wiki/MIT_Lincoln_Laboratory" title="MIT Lincoln Laboratory">L</a></li> <li><a href="/wiki/SM-65_Atlas" title="SM-65 Atlas">N</a></li> <li><a href="/wiki/SM-68_Titan" title="SM-68 Titan">P</a></li> <li><a href="/wiki/PGM-17_Thor" title="PGM-17 Thor">Q</a></li> <li><a href="/wiki/LGM-30_Minuteman" title="LGM-30 Minuteman">R</a></li> <li><a href="/wiki/Samos_(satellite)" title="Samos (satellite)">S (I)</a></li> <li><a href="/wiki/Missile_Defense_Alarm_System" title="Missile Defense Alarm System">S (II)</a></li></ul></li> <li>6961</li> <li>6971</li> <li>6981</li> <li>6991</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">700–799</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>700–7351</li> <li><a href="/w/index.php?title=AN/APR-46&action=edit&redlink=1" class="new" title="AN/APR-46 (page does not exist)">736</a></li> <li>7371</li> <li>7381</li> <li>7391</li> <li>7401</li> <li><a href="/w/index.php?title=Tactical_Electronic_Warfare_System&action=edit&redlink=1" class="new" title="Tactical Electronic Warfare System (page does not exist)">741</a></li> <li><a href="/wiki/LANTIRN" title="LANTIRN">742</a></li> <li><a href="/wiki/LANTIRN" title="LANTIRN">743</a></li> <li>7441</li> <li><a href="/wiki/Military_Satellite_Communications_Directorate" title="Military Satellite Communications Directorate">745</a></li> <li>746–7531</li> <li><a href="/w/index.php?title=AN/ALM-234&action=edit&redlink=1" class="new" title="AN/ALM-234 (page does not exist)">754</a></li> <li>755–7991</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">800–899</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>8001</li> <li>8011</li> <li>802 <ul><li><a href="/w/index.php?title=System_802L&action=edit&redlink=1" class="new" title="System 802L (page does not exist)">L (I)</a></li> <li><a href="/w/index.php?title=High_Frequency_Global_Communication_System&action=edit&redlink=1" class="new" title="High Frequency Global Communication System (page does not exist)">L (II)</a></li></ul></li> <li>8031</li> <li>8041</li> <li>8051</li> <li><a href="/w/index.php?title=Range_Threat_System&action=edit&redlink=1" class="new" title="Range Threat System (page does not exist)">806</a></li> <li><a href="/wiki/Defense_Support_Program" title="Defense Support Program">807</a></li> <li>808–8161</li> <li><a href="/w/index.php?title=Technical_Sensor_Collection_Systems&action=edit&redlink=1" class="new" title="Technical Sensor Collection Systems (page does not exist)">817</a></li> <li>8181</li> <li>8191</li> <li>8201</li> <li>8211</li> <li>8221</li> <li><a href="/w/index.php?title=System_823L&action=edit&redlink=1" class="new" title="System 823L (page does not exist)">823</a></li> <li>824–8311</li> <li><a href="/wiki/Defense_Meteorological_Satellite_Program" title="Defense Meteorological Satellite Program">832</a></li> <li>8331</li> <li><a class="mw-selflink selflink">834</a></li> <li>835–8451</li> <li><a href="/w/index.php?title=Range_Threat_System&action=edit&redlink=1" class="new" title="Range Threat System (page does not exist)">846</a></li> <li>847–8991</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">900–999</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>900–9511</li> <li><a href="/wiki/Douglas_C-47_Skytrain" title="Douglas C-47 Skytrain">952</a></li> <li>8531</li> <li>8541</li> <li>8551</li> <li><a href="/wiki/Douglas_DC-6" title="Douglas DC-6">956</a></li> <li>957–9671</li> <li><a href="/w/index.php?title=Pacer_Harmony&action=edit&redlink=1" class="new" title="Pacer Harmony (page does not exist)">968</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>1 Unknown or not assigned</div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Orienteering" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Orienteering" title="Template:Orienteering"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Orienteering" title="Template talk:Orienteering"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Orienteering" title="Special:EditPage/Template:Orienteering"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Orienteering" style="font-size:114%;margin:0 4em"><a href="/wiki/Orienteering" title="Orienteering">Orienteering</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><a href="/wiki/History_of_orienteering" title="History of orienteering">History of orienteering</a></li> <li><a href="/wiki/List_of_orienteering_events" title="List of orienteering events">List of orienteering events</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Sport disciplines</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/International_Orienteering_Federation" title="International Orienteering Federation">IOF</a>-<a href="/wiki/Sports_governing_body" title="Sports governing body">governed</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Foot_orienteering" title="Foot orienteering">Foot orienteering</a></li> <li><a href="/wiki/Mountain_bike_orienteering" title="Mountain bike orienteering">Mountain bike orienteering</a></li> <li><a href="/wiki/Ski_orienteering" title="Ski orienteering">Ski orienteering</a></li> <li><a href="/wiki/Trail_orienteering" title="Trail orienteering">Trail orienteering</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/International_Amateur_Radio_Union" title="International Amateur Radio Union">IARU</a>-<a href="/wiki/Sports_governing_body" title="Sports governing body">governed</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Amateur_radio_direction_finding" title="Amateur radio direction finding">Amateur radio direction finding</a> <ul><li><a href="/wiki/Fox_Oring" title="Fox Oring">Fox Oring</a></li> <li><a href="/wiki/Radio_Orienteering_in_a_Compact_Area" title="Radio Orienteering in a Compact Area">Radio Orienteering in a Compact Area</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other sports</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Canoe_orienteering" title="Canoe orienteering">Canoe orienteering</a></li> <li><a href="/wiki/Car_orienteering" title="Car orienteering">Car orienteering</a></li> <li><a href="/wiki/Mountain_marathon" title="Mountain marathon">Mountain marathon</a></li> <li><a href="/wiki/Mounted_orienteering" title="Mounted orienteering">Mounted orienteering</a></li> <li><a href="/wiki/Rogaining" title="Rogaining">Rogaining</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Adventure_racing" title="Adventure racing">Adventure racing</a></li> <li><a href="/wiki/Alleycat_race" title="Alleycat race">Alleycat race</a></li> <li><a href="/wiki/Fell_running" title="Fell running">Fell running</a></li> <li><a href="/wiki/Relay_race" title="Relay race">Relay race</a></li> <li><a href="/wiki/Transmitter_hunting" title="Transmitter hunting">Transmitter hunting</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Equipment</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Event</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Control_point_(orienteering)" title="Control point (orienteering)">Control point</a></li> <li><a href="/wiki/Course_(orienteering)" title="Course (orienteering)">Course</a></li> <li><a href="/wiki/Orienteering_map" title="Orienteering map">Map</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Personal</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Compass" title="Compass">Compass</a> <ul><li><a href="/wiki/Hand_compass" title="Hand compass">hand</a></li> <li><a href="/wiki/Protractor_compass" class="mw-redirect" title="Protractor compass">protractor</a></li> <li><a href="/wiki/Thumb_compass" title="Thumb compass">thumb</a></li></ul></li> <li><a href="/wiki/Eye_protection" title="Eye protection">Eye protectors</a></li> <li><a href="/wiki/Gaiters" title="Gaiters">Gaiters</a></li> <li><a href="/wiki/Headlamp_(outdoor)" title="Headlamp (outdoor)">Headlamp</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Exceptions</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Backpacking_(wilderness)#Equipment" class="mw-redirect" title="Backpacking (wilderness)">Backpacking</a></li> <li><a href="/wiki/Satellite_navigation" title="Satellite navigation">Satellite navigation</a></li> <li><a href="/wiki/Whistle" title="Whistle">Whistle</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a rel="nofollow" class="external text" href="https://orienteering.sport/iof/it/list-of-software-for-orienteering/">Software</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Proprietary</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/w/index.php?title=OCAD_(software)&action=edit&redlink=1" class="new" title="OCAD (software) (page does not exist)">OCAD</a></li> <li><a href="/w/index.php?title=Condes_(software)&action=edit&redlink=1" class="new" title="Condes (software) (page does not exist)">Condes</a></li> <li><a href="/w/index.php?title=SportSoftware&action=edit&redlink=1" class="new" title="SportSoftware (page does not exist)">SportSoftware</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Open-source</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/w/index.php?title=OpenOrienteering_Mapper&action=edit&redlink=1" class="new" title="OpenOrienteering Mapper (page does not exist)">OpenOrienteering Mapper</a></li> <li><a href="/w/index.php?title=Purple_Pen&action=edit&redlink=1" class="new" title="Purple Pen (page does not exist)">Purple Pen</a></li> <li><a href="/w/index.php?title=MeOS_(software)&action=edit&redlink=1" class="new" title="MeOS (software) (page does not exist)">MeOS</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a rel="nofollow" class="external text" href="https://orienteering.sport/iof/it/list-of-software-for-orienteering/">Video games</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Catching_Features" title="Catching Features">Catching Features</a></li> <li><a href="/w/index.php?title=Suunnistussimulaattori&action=edit&redlink=1" class="new" title="Suunnistussimulaattori (page does not exist)">Suunnistussimulaattori</a></li> <li><a href="/w/index.php?title=WinOL&action=edit&redlink=1" class="new" title="WinOL (page does not exist)">WinOL / WinOL II Oriantica</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Fundamentals</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Map" title="Map">Map</a> <ul><li><a href="/wiki/Orienteering_map" title="Orienteering map">orienteering map</a></li></ul></li> <li><a href="/wiki/Navigation" title="Navigation">Navigation</a> <ul><li><a href="/wiki/Cardinal_direction" title="Cardinal direction">cardinal direction</a></li> <li><a href="/wiki/Position_resection" class="mw-redirect" title="Position resection">resection</a></li> <li><a href="/wiki/Route_choice_(orienteering)" title="Route choice (orienteering)">route choice</a></li> <li><a href="/wiki/Wayfinding" title="Wayfinding">wayfinding</a></li> <li><a href="/wiki/Waypoint" title="Waypoint">waypoint</a></li></ul></li> <li><a href="/wiki/Racing" title="Racing">Racing</a> <ul><li><a href="/wiki/Hiking" title="Hiking">hiking</a></li> <li><a href="/wiki/Running" title="Running">running</a></li> <li><a href="/wiki/Walking" title="Walking">walking</a></li> <li><a href="/wiki/Skiing" title="Skiing">skiing</a></li> <li><a href="/wiki/Mountain_biking" title="Mountain biking">mountain biking</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Organisations / lists</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/International_Orienteering_Federation" title="International Orienteering Federation">International Orienteering Federation</a> <ul><li><a href="/wiki/Category:National_members_of_the_International_Orienteering_Federation" title="Category:National members of the International Orienteering Federation">members</a></li></ul></li> <li><a href="/wiki/List_of_orienteering_clubs" title="List of orienteering clubs">List of clubs</a></li> <li><a href="/wiki/List_of_orienteers" title="List of orienteers">List of orienteers</a> <ul><li><a href="/wiki/List_of_orienteers#By_country" title="List of orienteers">by country</a></li> <li><a href="/wiki/List_of_orienteers#Innovators" title="List of orienteers">innovators</a></li></ul></li> <li><a href="/wiki/List_of_orienteering_events" title="List of orienteering events">List of events</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Non-sport related</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Adventure_travel" title="Adventure travel">Adventure travel</a></li> <li><a href="/wiki/Bicycle_touring" title="Bicycle touring">Bicycle touring</a></li> <li><a href="/wiki/Climbing" title="Climbing">Climbing</a></li> <li><a href="/wiki/Hiking" title="Hiking">Hiking</a></li> <li><a href="/wiki/Hunting" title="Hunting">Hunting</a></li> <li><a href="/wiki/Location-based_game" title="Location-based game">Location-based game</a> <ul><li><a href="/wiki/Geocaching" title="Geocaching">geocaching</a></li> <li><a href="/wiki/Poker_run" title="Poker run">poker run</a></li></ul></li> <li><a href="/wiki/Orienteering_(scouting)" title="Orienteering (scouting)">Scoutcraft orienteering</a> <ul><li><a href="/wiki/Backpacking_(wilderness)" class="mw-redirect" title="Backpacking (wilderness)">wilderness</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Competitions</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Foot_orienteering" title="Foot orienteering">Foot orienteering</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/World_Orienteering_Championships" title="World Orienteering Championships">World Championships</a> <ul><li><a href="/wiki/Junior_World_Orienteering_Championships" title="Junior World Orienteering Championships">Junior</a></li> <li><a href="/wiki/World_Masters_Orienteering_Championships" title="World Masters Orienteering Championships">Masters</a></li> <li><a href="/wiki/World_University_Orienteering_Championships" title="World University Orienteering Championships">University</a></li></ul></li> <li><a href="/wiki/Orienteering_World_Cup" title="Orienteering World Cup">World Cup</a></li> <li><a href="/wiki/Orienteering_at_the_World_Games" title="Orienteering at the World Games">World Games</a></li> <li><a href="/wiki/European_Orienteering_Championships" title="European Orienteering Championships">European Championships</a> <ul><li><a href="/wiki/European_Youth_Orienteering_Championships" title="European Youth Orienteering Championships">Youth</a></li> <li><a href="/w/index.php?title=European_University_Orienteering_Championships&action=edit&redlink=1" class="new" title="European University Orienteering Championships (page does not exist)">University</a></li></ul></li> <li><a href="/wiki/North_American_Orienteering_Championships" title="North American Orienteering Championships">North American Championships</a></li> <li>Open events <ul><li><a href="/wiki/O-Ringen" title="O-Ringen">O-Ringen</a></li> <li><a href="/wiki/Jukola_relay" title="Jukola relay">Jukola</a></li> <li><a href="/wiki/Tiomila" title="Tiomila">Tiomila</a></li> <li><a href="/wiki/Kainuu_Orienteering_Week" title="Kainuu Orienteering Week">Kainuu Orienteering Week</a></li> <li><a href="/wiki/Jan_Kjellstr%C3%B6m_International_Festival_of_Orienteering" title="Jan Kjellström International Festival of Orienteering">Jan Kjellström Festival</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Ski_orienteering" title="Ski orienteering">Ski orienteering</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/World_Ski_Orienteering_Championships" title="World Ski Orienteering Championships">World Championships</a> <ul><li><a href="/wiki/Junior_World_Ski_Orienteering_Championships" title="Junior World Ski Orienteering Championships">Junior</a></li></ul></li> <li><a href="/wiki/World_Cup_in_Ski_Orienteering" title="World Cup in Ski Orienteering">World Cup</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Mountain_bike_orienteering" title="Mountain bike orienteering">Mountain bike orienteering</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/World_Mountain_Bike_Orienteering_Championships" title="World Mountain Bike Orienteering Championships">World Championships</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Trail_orienteering" title="Trail orienteering">Trail orienteering</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/World_Trail_Orienteering_Championships" title="World Trail Orienteering Championships">World Championships</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /> <a href="/wiki/Category:Orienteering" title="Category:Orienteering">Category</a></li> <li><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/3/37/People_icon.svg/16px-People_icon.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/37/People_icon.svg/24px-People_icon.svg.png 1.5x, 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href="https://catalogue.bnf.fr/ark:/12148/cb12294604n">France</a></li><li><a rel="nofollow" class="external text" href="https://data.bnf.fr/ark:/12148/cb12294604n">BnF data</a></li><li><a rel="nofollow" class="external text" href="https://aleph.nkp.cz/F/?func=find-c&local_base=aut&ccl_term=ica=ph117577&CON_LNG=ENG">Czech Republic</a></li><li><a rel="nofollow" class="external text" href="http://olduli.nli.org.il/F/?func=find-b&local_base=NLX10&find_code=UID&request=987007556174505171">Israel</a></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><a rel="nofollow" class="external text" href="https://catalog.archives.gov/id/10638667">NARA</a></li></ul></div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" 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