Research on BDS/GPS High-precision Long-period Ephemeris Extrapolation Technology

In order to improve the surface satellite positioning efficiency of the underwater vehicle, a simple and efficient high-precision long-period ephemeris extrapolation technology method is proposed to solve the problem of too long time for the first satellite positioning of the submarine after a long underwater navigation. This method effectively shortens the satellite positioning time by constructing the ephemeris parameter extrapolation model and the satellite long-period clock error prediction model. The simulation experiment results show that the satellite orbit forecast output by the model meets the requirements of equipment accuracy, and the satellite positioning time is significantly shortened.