Abstract:

Clock offset drifts occur for the lack of inter-satellite system time. In the ensemble working mode, inter-satellite system time algorithms are proposed in this paper. The two prediction methods of initial value of clock-velocity are put forward for building system time, i.e. initial value of clock-velocity is predicted by using former two clock offsets of first day, and is predicted by using former two clock offsets of each day. Simulation results show that the two algorithms are reasonable. The new system time is compared to international GNSS (Global Navigation Satellite System) service time (IGST); the clock offset drift of 60 days is less than 100 ns. The system time built by use of the first prediction method is more stable.

Key words: Inter-satellite system time, Ensemble working mode, On-board clock-velocity prediction, Weight algorithm, Stability analysis