北斗三号B2b信号改正广播星历精度评估及PPP应用

Accuracy evaluation of BeiDou-3 PPP-B2b signal

北斗三号全球卫星导航系统(BDS-3) B2b信号是由3颗地球同步轨道(GEO)卫星播发改正信号组成,可为用户提供公开、免费的高精度服务,对北斗卫星导航系统(BDS)在国土测绘、海洋测绘以及桥梁建筑物健康监测等领域的高精度应用具有重要意义. BDS-3 B2b信号的精度评估是实现其高精度应用的重要环节.首先利用BDS-3 B2b信号改正广播星历产品,并获得改正后的精密轨道和钟差产品.然后,以武汉大学国际GNSS服务(IGS)分析中心提供的事后精密产品(WUM)为参考,评估了由B2b信号改正后的精密轨道和钟差产品的精度.结果表明:改正后北斗卫星轨道的径向(R)、切向(A)、法向(C)误差的均方根(RMS)分别为6.26 cm、24.21 cm、21.79 cm,钟差差值的标准差(STD)均值为0.33 ns.最后,利用改正后的精密轨道和钟差产品进行精密单点定位(PPP)验证,结果表明:PPP定位东(E)、北(N)、天顶(U)方向精度分别为0.06 m、0.05 m、0.13 m.说明广播星历通过B2b改正后的精密轨道和钟差产品与IGS事后精密产品精度相当,可满足单站实时高精度定位与导航的应用需求.

The BeiDou-3 Navigation Satellite System(BDS-3)B2b signal is a signal broadcast by three geosynchronous orbit satellites of BDS-3, which can provide users with open and free high-precision services, and is of great significance on high-precision applications in several fields such as land surveying,marine surveying and health monitoring of bridges and buildings. The accuracy evaluation of precision single point positioning(PPP)-B2b signals is a key link to realize its high-precision applications. To evaluate the accuracy of PPP-B2b products, by correcting the broadcast ephemeris with PPP-B2b signals using selfcompiled program, the precise orbit and clock products corrected by the PPP-B2b products were obtained.Taking the after-event precision products(WUM)provided by the IGS Data Center of Wuhan University as a reference, the precision of the precision products corrected by PPP-B2b is evaluated. The results show that the root-mean-square(RMS)value of the radial direction(R), tangential direction(A)and normal direction(C)of the BeiDou satellite orbit after correction is 6.26 cm, 24.21 cm, and 21.79 cm respectively, and the average value of the standard deviation(STD)of the clock difference is 0.33 ns. Finally, the results of the PPP using the corrected precise orbit and clock products show that the accuracy of PPP positioning in the east(E), north(N)and zenith(U)directions is 0.07 m, 0.07 m and 0.15 m respectively. The precise orbit and clock error products of broadcast ephemeris corrected by BDS-3 B2b are as accurate as IGS post-event precision products, which can meet the application requirements of single-station real-time high-precision positioning and navigation.