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Samples of three GPS satellites' orbits over a five-year period (2013 to 2018) USA-242 · USA-239 · USA-151 · Earth As of 22 January 2025, 83 Global Positioning System navigation satellites have been built: 31 are launched and operational, 3 are in reserve or testing, 43 are retired, 2 were lost during launch, and 1 prototype was never launched. 3 Block III satellites have completed ...
Satellites are uniquely identified by a serial number called space vehicle number (SVN) which does not change during its lifetime. In addition, all operating satellites are numbered with a space vehicle identifier (SV ID) and pseudorandom noise number (PRN number) which uniquely identifies the ranging codes that a satellite uses.
In case of the GPS, the receivers are closer to Earth than the satellites, causing the clocks at the altitude of the satellite to be faster by a factor of 5×10 −10, or about +45.8 μs/day. This gravitational frequency shift is measurable.
If the number of GPS satellites is 23 or fewer, RAIM availability must be checked using approved ground-based prediction software. Several GPS-related systems also provide integrity signals separate from GPS. Among these is the WAAS system, which uses separate signals broadcast from different satellites to indicate these problems directly.
USA-1, also known as Navstar 9, GPS I-9 and GPS SVN-9, was an American navigation satellite launched in 1984 as part of the Global Positioning System development programme. It was the ninth of eleven Block I GPS satellites to be launched, [ 2 ] and the first satellite to receive a USA designation .
Vehicle navigation on a personal navigation assistant Garmin eTrex10 edition handheld. A satellite navigation device or satnav device, also known as a satellite navigation receiver or satnav receiver or simply a GPS device, is a user equipment that uses satellites of the Global Positioning System (GPS) or similar global navigation satellite systems (GNSS).
USA-232, also known as GPS IIF-2, and GPS SVN-63, is an American navigation satellite which forms part of the Global Positioning System. It was the second of twelve Block IIF satellites to be launched.
USA-266, also known as GPS IIF-12, GPS SVN-70 and NAVSTAR 76, is an American navigation satellite which forms part of the Global Positioning System. It was the twelfth of twelve Block IIF satellites to be launched.