Alternative Timing Networks with GPS
NAVAL RESEARCH LAB WASHINGTON DC
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An approach to determining accurate time from GPS with an independent network of receiving stations has been investigated. The methods of using the Global Positioning System GPS for transferring time in previous work has been by the common view and melting pot methods. Both of these techniques have used simplified single frequency receivers operating on the clearacquisition CA GPS codes and assumes that the satellite transmissions are quality observables producing GPS time, accurately traceable to UTCUSN0. In the case of common view, the position of the satellite is assumed to be accurately known from the satellite transmissions. Then the time delays due to position at the two common view sites may be accurately measured for time comparisons. In the melting pot method, an individual site measures GPS Time as determined from observing all GPS satellites in view resulting in an accurate over-solution of the GPS system time. The satellite broadcasts then provide the UTC - GPS time correction. The investigation into an independent network was performed on the basis of using the simplified CIA receiving equipment to produce accurate timing information regardless of the GPS broadcast information accuracy. The technique can be used to improve the inherent capabilities of these single frequency receivers or maintain accuracy with degraded GPS signals. The similarities with geodetic positioning using GPS will be described. A proof-of-concept experiment will be discussed and data presented to verify the technique.
- Test Facilities, Equipment and Methods
- Navigation and Guidance