Real Time Precise Satellite Clock Estimation for Quad-System GPS/GLONASS/GALILEO/BDS

摘要

With the fast-pacing development of the GNSS, the number of satellites in orbit is increasing, and the accuracy of the multi-GNSS orbits is gradually improved, which makes it possible to use the GPS/GLONASS/BDS/Galileo quad-system model to achieve real-time precise point positioning (PPP). Usually, predicted orbits can be considered known because of its high accuracy. The high precision real-time satellite clock is a prerequisite for real-time PPP. In this paper, the estimation model and strategy of the quad-system satellite clock errors are studied, and the quad-system satellite clock errors are calculated based on the square root information filter method. Compared with the final GFZ 30 s precise clock products, the accuracy of real-time quad-system clock was about 0.06 ns which shows a high agreement. The kinematic PPP solutions based on the real-time quad-system clocks were with the solutions based on GFZ clock products, which verifies the correctness of the model and strategy.