GPS/BDS Real-Time Precise Point Position Based on BDS Short Message Communication

Real-time precise point positioning (PPP) is an important way for precise location services at sea, which break away from the influence by the distance of base station, but depends on the real-time broadcast of orbit and clock corrections. The existing offshore multi-system real-time PPP methods based on global BDS short message communication (GBSMC) have completed decimeter-level PPP, but which depends on real-time acquisition of user location, exposing user privacy. Therefore, this paper proposes an ocean GPS/BDS real-time PPP resolution adjusting method based on single GBSMC card. First, the distribution ranges of clock and orbit corrections were redefined to ±63.5m and ±3.5m for GPS and BDS satellites. Second, the resolution adjustment scheme is used to realize the compression encoding while ensuring the positioning accuracy, and the encoding format is determined. Third, the minute-level delay broadcasting scheme based on BDS short messages is determined, due to the decline of GPS and BDS clock and orbit accuracy in centimeter level with the 1min delay. Last, the method was verified at 6 global stations, while the positioning accuracy were 0.0618 m, 0.0673 m and 0.0943 m in E, N and U directions with longer convergence time than original SSR.