BDS/GPS实时钟差估计及其精度分析

BDS/GPS real-time clock estimation and its accuracy analysis

全球卫星导航系统(global navigation satellite system, GNSS)实时精密单点定位(precise point positioning, PPP)具有实时、广域定位的优点,目前在应用中存在实时钟差估计精度低的问题。文章利用平方根信息滤波(square root information filter, SRIF)实现实时卫星钟差滤波估计,采用全球80个国际GNSS服务(International GNSS Service, IGS)和多模GNSS试验跟踪网(Multi-GNSS Experiment, MGEX)的测站数据进行实时估钟,估钟结果与德国地球科学研究中心(GeoForschungsZentrum, GFZ)事后钟差进行对比,GPS钟差精度约为0.27 ns,北斗卫星导航系统(BeiDou Navigation Satellite System, BDS)地球静止轨道(Geostationary Earth Orbit, GEO)卫星为1.37 ns,倾斜地球同步轨道(Inclined Geosynchronous Orbit, IGSO)卫星为0.47 ns,中地球轨道(Medium Earth Orbit, MEO)卫星为0.39 ns。基于精密轨道和估计的实时钟差对6个IGS/MGEX测站进行定位实验,结果表明,GPS和BDS+GPS组合2种模式在定位收敛后达到cm级的定位精度,满足实时定位的要求。

Global navigation satellite system(GNSS) real-time precise point positioning(PPP) has the advantages of real-time and wide area positioning. At present, this technology is limited by the low precision of real-time clock estimation. This paper used square root information filtering(SRIF) to achieve real-time satellite clock filtering estimation. The data from 80 International GNSS Service(IGS) and Multi-GNSS Experiment(MGEX) stations was used to estimate the real-time satellite clock, comparing with the GeoForschungsZentrum(GFZ) final clock. The accuracy of real-time GPS clock was 0.27 ns, the accuracy of real-time BeiDou Navigation Satellite System(BDS) Geostationary Earth Orbit(GEO) clock, the Inclined Geosynchronous Orbit(IGSO), and the Medium Earth Orbit(MEO) was 1.37 ns, 0.47 ns, and 0.39 ns, respectively. The PPP solution of the six IGS/MGEX stations based on the precise orbit and real-time GPS and BDS satellite clock showed that the accuracy of position about GPS and BDS/GPS combination model after convergence could achieve centimeter level, which met the requirements of real-time positioning.