Galileo系统服务中断前后广播星历精度对比分析

Comparison and analysis of broadcast ephemeris accuracy before and after Galileo system service interruption

2019年7月中旬发生的Galileo服务中断事件,在整个卫星导航发展史上都是较为罕见的重大事故。本文选取Galileo服务中断前后的广播星历,从纵向(利用中断前后29 d的数据)和横向(与其他主要系统进行对比)两个维度,通过卫星位置、速度、钟差、空间信号测距误差4个方面,对中断事件前后广播星历计算精度进行了较为全面的分析。结果表明:从纵向维度来看,服务中断前,Galileo健康卫星数发生剧烈变化,卫星钟差精度普遍发散,卫星位置、速度精度未发生明显异常,服务恢复后各项指标随之恢复正常。从横向维度来看,与GPS相比,Galileo系统目前在卫星位置速度精度、卫星钟差精度方面已表现出优于GPS的性能,在空间信号测距误差(SISRE)方面,Galileo轨道精度具有明显优势,平均SISRE达到0.27 m。GPS与BDS相当,GPS平均SISRE达到0.61 m,BDS的3类卫星MEO、IGSO和GEO分别达到0.76、0.58和0.68 m;QZSS的IGSO和GEO卫星平均SISRE分别达到0.85和0.99 m。GLONASS轨道精度稍差,平均SISRE为1.05 m。

The Galileo service interruption event in mid July 2019 is a relatively rare major accident in the whole history of satellite navigation development. This paper selects the broadcast ephemeris before and after Galileo service interruption,from two dimensions of vertical( using the data of 29 days before and after interruption) and horizontal( comparing with other major systems),through the four aspects of satellite position,speed,clock difference and SISRE( signal-in-space range error),analyzes the calculation accuracy of broadcast ephemeris before and after interruption. The results show that: from the vertical dimension,before the service interruption,the number of Galileo healthy satellites changes dramatically,the accuracy of satellite clock difference is widely divergent,and the accuracy of satellite position and speed is not significantly abnormal. After the service is restored,all indicators return to normal. From the horizontal dimension,compared with GPS,Galileo system has shown better performance in the accuracy of satellite position,speed and clock. In the field of SISRE,Galileo has obvious advantage with an average SISRE of 0.27 m. GPS and BDS have the comparable orbit accuracy. The average SISRE of GPS is about 0.61 m,and that of BDS MEO,IGSO and GEO is respectively 0.76,0.58,and 0.68 m. The average SISRE of QZSS( IGSO) and QZSS( GEO) is respectively 0. 85 and 0. 99 m. GLONASS has slightly poor orbit accuracy,with an average SISRE of 1.05 m.