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What is the military P-code used by Navstar GPS satellites?
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GPS
U.S. Navstar Global Positioning System (GPS) satellite in orbit over Earth, shown in an artist's conception.
The military P-code, or precision code, is a 10-megabit-per-second pseudo-random binary pulse train used by Navstar GPS satellites to provide highly accurate positioning data.1
This signal is broadcast on two frequenciesâ1575.42 megahertz and 1227.6 megahertzâand allows for significantly higher precision than the civilian C/A-code. While the unaugmented civilian signal typically provides horizontal accuracy within 10 metres, the unaugmented military signal achieves a horizontal error variance of less than 3 metres.1