Analysis of real-time multi-GNSS satellite products of Wuhan University for rapid response of precise positioning

Abstract

When users need to quickly process GNSS data, they often need the satellite orbit and clock products with the minimum latency and the highest precision, and it is a good solution to receive the real-time satellite RTCM SSR correction stream to recover the precise satellite orbit and clock products in real time and then store them in an offline repository for rapid response of precise positioning. In this paper, the real-time multi-GNSS orbit and clock RTCM SSR correction stream broadcast by SSRC00WHU0 mountpoint of Wuhan University is used to recover precise satellite orbit and clock products in real time. First, the seven-day orbit files and clock files were obtained and stored locally, and compared with the final MGEX precise satellite orbit and clock products. The results show that the real-time orbit and clock products of GPS and Galileo satellites have the best accuracy, followed by GLONASS satellites and BDS satellites. The real-time orbit products can reach the accuracy level of 5 cm for GPS satellites, 8 cm for Galileo satellites, 15 cm for GLONASS satellites and 16 cm for BDS-3 satellites, and the real-time clock products can reach the accuracy level of 0.43 ns for GPS satellites, 0.44 ns for Galileo satellites, 0.91 ns for GLONASS satellites and 3.14 ns for BDS satellites. Then, the observation data of 20 IGS stations randomly distributed around the world from DOY 150 to 156 in 2021 were processed by static precise point positioning (PPP) mode using the recovered real-time products. The results show that the average positioning accuracy can reach 1.57 cm, 0.76 cm and 1.67 cm in east, north and up direction for static PPP, respectively. Finally, using the recovered real-time products and the final products, the GPS observation data collected in aviation were processed in pseudo real-time in a kinematic mode. The results show that the RMSs of positioning errors are 8.5 cm, 2.4 cm and 16.5 cm in the east, north and up direction, respectively. In addition, one-day multi-GNSS observation data at 20 IGS stations were processed in a kinematic PPP mode, and the results show that the average positioning accuracy is 3.11 cm, 2.04 cm and 4.94 cm in east, north and up directions.