Editing Geostationary orbit (section)

===Navigation===
{{further|GNSS augmentation}}

[[Image:SBAS Service Areas.png|thumb|upright=1.35|Service areas of satellite-based augmentation systems (SBAS).<ref name="gmv">{{cite web|url=https://www.gmv.com/en/Company/Communication/News/2016/06/SBASAfrica.html| publisher=[[GMV (company)|GMV]] |title= Deployment of an SBAS system demonstration in Southern Africa |date=August 6, 2016|access-date=October 1, 2019}}</ref>]]

Geostationary satellites can be used to augment [[GNSS]] systems by relaying [[Error analysis for the Global Positioning System#Ephemeris and clock errors|clock]], [[Error analysis for the Global Positioning System#Ephemeris and clock errors|ephemeris]] and [[Error analysis for the Global Positioning System#Atmospheric effects|ionospheric]] error corrections (calculated from ground stations of a known position) and providing an additional reference signal.<ref>{{Cite web|url=https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/waas/howitworks/|title=Satellite Navigation – WAAS – How It Works|publisher=[[Federal Aviation Administration|FAA]]|date=June 12, 2019}}</ref> This improves position accuracy from approximately 5m to 1m or less.<ref>{{cite web|url=https://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system |archive-url=https://web.archive.org/web/20190707040109/https://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system |archive-date=July 7, 2019|publisher=Geoscience Australia|title=Satellite Based Augmentation System test-bed project}}</ref>

Past and current navigation systems that use geostationary satellites include:
* The [[Wide Area Augmentation System]] (WAAS), operated by the [[United States]] [[Federal Aviation Administration]] (FAA);
* The [[European Geostationary Navigation Overlay Service]] (EGNOS), operated by the [[European Satellite Services Provider|ESSP]] (on behalf of [[EU]]'s [[European GNSS Agency|GSA]]);
* The [[Multi-functional Satellite Augmentation System]] (MSAS), operated by [[Japan]]'s [[Ministry of Land, Infrastructure, Transport and Tourism|Ministry of Land, Infrastructure and Transport]] [[Japan Civil Aviation Bureau]] (JCAB);
* The [[GPS Aided Geo Augmented Navigation]] (GAGAN) system being operated by [[India]].<ref>{{cite press release|url=http://isro.gov.in/pressrelease/scripts/pressreleasein.aspx?Jan03_2014|date=January 3, 2014|title=GAGAN System Certified for RNP0.1 Operations|archive-url=https://web.archive.org/web/20140103233538/http://isro.gov.in/pressrelease/scripts/pressreleasein.aspx?Jan03_2014|archive-date=January 3, 2014|publisher=[[Indian Space Research Organisation]]}}</ref><ref>{{Cite news|url=https://www.thehindu.com/news/national/kerala/gagan-system-ready-for-operations/article5565700.ece|title=GAGAN system ready for operations|first=S. Anil|last=Radhakrishnan|date=January 11, 2014|work=The Hindu}}</ref>
* The commercial [[StarFire (navigation system)|StarFire navigation system]], operated by [[Deere & Company|John Deere]] and [[C-Nav]] Positioning Solutions ([[Oceaneering]]);
* The commercial [[Starfix DGPS System]] and [[OmniSTAR]] system, operated by [[Fugro]].<ref>{{Cite conference|title=Ten Years of Experience with A Commercial Satellite Navigation System|last= Ott |first= L. E. |conference=International Cooperation in Satellite Communications, Proceedings of the AIAA/ESA Workshop |place= ESTEC, Noordwijk, the Netherlands. |editor-first=C. |editor-last=Mattok |page=101 |bibcode=1995ESASP.372..101O}}</ref>