一种基于时间和频率传递的北斗导航卫星应用研究

Applications of Two-Way Satellite Time and Frequency Transfer in the Beidou Navigation Satellite System

双向卫星时间频率传递(TWSTFT)搭载在北斗卫星导航系统装置(BDS)上可以计算出卫星和地面主时钟之间的时钟误差。双向卫星时间频率传递(TWSTFT)是一种高精度的实时观测方法 ,因为大多数的系统误差,如轨道误差、位置误差、对流层和电离层延迟误差可以通过计算双向伪距差分消除。另一种方法 ,多卫星精密定轨(MPOD)方法 ,可以用于估计卫星时钟误差。本文通过MPOD时钟估计的比较,论述了基于时间和频率传递的北斗导航卫星应用,如卫星钟差预报、导航系统的实时监控,轨道卫星时钟的性能评价等。实验结果表明,对于卫星时钟的预测精度双向卫星时间频率传递(TWSTFT)要高于多卫星精密定轨(MPOD)。国际GNSS服务分析中心(IGS ACS)通过连续五周的比较,发现北斗时间(BDT)和全球定位系统时间(GPST)两者的参考时间差可以在几十纳秒级内实现。因为MPOD时钟预算精度不够高,TWSTFT时钟误差可以在104秒间隔内获得更精确的卫星时钟的性能评估。通过BDS与GPS卫星时钟的性能比较,我们发现在10~3秒的时间间隔内BDS时钟稳定性约10^(-12),其类似于GPS IIR。

A two-way satellite time and frequency transfer （TWSTFT） device equipped in the Beidou navigation satellite system （BDS） can calculate clock error between satellite and ground master clock. TWSTFT is a real-time method with high accuracy because most system errors such as orbital error, station position error, and tropospheric and ionospheric delay error can be eliminated by calculating the two-way pseudorange difference. Another method, the multi-satellite precision orbit determination （MPOD） method, can be applied to estimate satellite clock errors. By comparison with MPOD clock estimations, this paper discusses the applications of the BDS TWSTFT clock observations in satellite clock measurement, satellite clock prediction, navigation systemtime monitor, and satellite clock performance assessment in orbit. The results show that with TWSTFT clock observations, the accuracy of satellite clock prediction is higher than MPOD. Five continuous weeks of comparisons with International GNSS Service （IGS） analysis centers （ACs） show that the reference time difference between Beidou time （BDT） and global positoning system （GPS） time （GPST） realized IGS ACs is in the tens of nanoseconds. Applying the TWSTFT clock error observations may obtain more accurate satellite clock performance evaluation in the 104 s interval because the accuracy of the MPOD clock estimation is not sufficiently high. By comparing the BDS and GPS satellite clock performance, it is found that the BDS clock stability at the 103 s interval is approximately 10-12, it is similar to the GPS IIR.