The Global Positioning System (GPS) will consist of a mixed constellation of Block 2/2A ground navigated and Block 2R autonomously navigated (Autonav) satellites for many years starting in 1996. The GPS time references for these two types of subconstellations must be synchronized to within a few nanoseconds if user navigation accuracy is to be preserved. A technique for achieving Root Mean Square (RMS) phase and rate synchronization of 2.9 ns and 0.13 ns/hr, by steering the ground system to Autonav, is described and validated by simulation. Coincidental with synchronization steering, it is shown that Autonav ensemble time (for a subconstellation of as few as four satellites) can be maintained to within 20.7 ns of Universal Time Coordinated (UTC) using a drift rate steering control law.
Mixed Constellation Synchronization of GPS Time
1992
4 pages
Report
No indication
English
Policies, Regulations, & Studies , Navigation Systems , Space Technology , Global positioning system , Navigation , Satellite navigation systems , Satellite networks , Synchronism , Time , Drift rate , Autonomous spacecraft clocks , Correction , Root-mean-square errors , Simulation , Steering , Time measurement
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