北斗在轨卫星广播星历精度分析

Precision Analysis of Bei Dou Satellites Broadcast Ephemeris

为分析北斗广播星历的精度,采用激光测距资料和精密星历作为参考进行分析。由于没有提供BDS-3试验卫星精密星历,本文设计了3天弧段的DBS-3试验卫星精密定轨试验,解算的轨道精度约为50 cm,钟差精度约为2 ns。之后联合国际GNSS监测评估系统i GMAS发布的事后BDS-2精密星历,对BDS-3/BDS-2广播星历轨道、钟差精度进行分析。为准确评估广播星历轨道精度,还采用SLR观测数据作为外部检核手段分析北斗在轨卫星广播星历轨道精度。统计了广播星历轨道误差的1D RMS和钟差误差的STD,结果表明:多数钟差精度优于10 ns,轨道精度优于5 m。另外为分析广播星历卫星钟的时频性能,计算了在轨卫星钟差的频率稳定度、漂移率和准确度,试验结果表明:BDS-3试验卫星各项性能指标普遍优于BDS-2,频率准确度、频率漂移率和频率稳定性指标计算结果显示BDS-3卫星相对于BDS-2卫星分别提升了42.8%,22.5%,9.5%。

In order to analyze the accuracy of the BDS broadcast ephemeris,the laser ranging and precise ephemeris are used as the reference to do some analysis. Since there is no BDS-3 experimental satellite precise ephemeris,this paper designs the DBS-3 experimental satellite precise orbit determination experiment with a 3-day arc,and the results show that the orbit and clock offsets accuracies are about 50 cm and 2 ns respectively. Then combined with the BDS-2 post precision satellites ephemeris obtained from the international GNSS monitoring assessment system（ i GMAS）,to evaluate the accuracy of the BDS-3/BDS-2 ephemeris-clock and ephemeris-orbit, in order to evaluate the ephemeris-orbit more accurately,the SLR observation data is used as an external means to evaluate the BDS satellite ephemeris-orbit accuracy,the 1 d RMS of the ephemeris-orbit and the STD of ephemeris-clock are counted,and the results show that most clock accuracies are better than 10 ns,the orbit accuracy is better than 5 m. In addition,in order to analyze the time-frequency performance of the ephemeris-clock,the frequency stability,the drift rate and the accuracy of the satellite clock offset are calculated. The experimental results show that the performance of the BDS-3 test satellites is generally better than that of the BDS-2. The performance indicators of the frequency accuracy,frequency drift rate and frequency stability calculated show that the BDS-3 satellite increases by 42. 8%,22. 5% and 9. 5% compared with the BDS-2.