广域实时精密定位与时间服务系统

广域实时精密定位与时间服务已成为GNSS应用领域研究热点,目前国内外学者围绕其模型算法已展开大量的研究。本文重点论述广域实时精密定位与时间服务数据的处理方法和服务系统,给出了基于不同基准约束的卫星钟差解算数学模型,提出通过引入外接原子钟测站、标准时间源(UTC/BDT)等不同时间基准,构建卫星拟稳基准、外接原子钟跟踪站拟稳基准及标准时间源等约束下的钟差解算模型,分析了时间基准对精密单点定位和精密单点授时的影响。本文采用实时卫星轨道、钟差、相位偏差、电离层延迟等服务产品及跟踪站实时数据,验证了系统产品可靠性及终端定位与时间服务性能。实测结果表明:GPS轨道径向精度1.8 cm,钟差STD精度约0.05 ns;BDS-3轨道径向精度6.7 cm,钟差STD精度优于0.1 ns;GPS和BDS-2电离层改正精度分别为0.74 TECU与1.03 TECU。基于该产品实现了用户端PPP、PPP-RTK及PPT、PPT-RTK服务,满足了用户实时厘米级定位和优于0.5 ns的单站时间传递服务,当采用GPS+BDS-2 PPP-RTK解算时,平面收敛至5 cm约需要12 min。

Real-time wide-area precise positioning and precise timing service system

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.