广域实时精密定位与时间服务系统

Wide-area real-time accurate positioning and timing service has become a hotspot in the field of GNSS. At present, domestic and foreign scholars have carried out a lot of valuable research on the model and algorithm. The method of data processing and service system construction for real-time wide-area precise positioning (WPP) and wide-area precise timing (WPT) is investigated in this paper. Various clock datums, including the quasi-stable datum of satellite clocks, the quasi-stable datum of station atomic clocks, and the datum of standard time, are proposed for the constraint on clock estimation solution by introducing stations that are linked to external atomic frequency standard or the source of standard time (UTC/BDT) in the solution. Also, the impact of clock datum on PPP, precise point timing (PPT) is analyzed. In this paper, the real-time products of the satellite orbit, clock errors, phase biases and ionospheric delays, as well as the real-time tracking station data, are utilized to verify the products reliability of the system and the performance of terminal positioning and timing service. The results of the real-time products indicate that the average RMS of radial orbit errors is 1.8 cm and 6.7 cm, and the average STD of clock errors is about 0.05 ns and better than 0.1 ns for GPS and BDS-3, respectively; the accuracy of ionospheric delays is 0.74 TECU and 1.03 TECU for GPS and BDS-2, respectively. Based on the above products, PPP/PPP-RTK and PPT/PPT-RTK services that meet real-time positioning of centimeter-level and one-way timing better than 0.5 ns are realized. It takes about 12 min to reach the positioning accuracy under 5 cm for the horizontal component in the GPS+BDS-2 PPP-RTK solution.