基于抗差估计的多GNSS共视基准站数据融合

Data fusion of GNSS common-view multi-reference stations based on robust estimation

为了满足远程时间用户对标准时间UTC(NTSC)纳秒级配送的需求,建立了一套标准时间远程复现系统。该系统目前使用的单基准终端服务模式,存在一定的风险,若单个接收机出现故障,会影响得到的本地时间和卫星钟之间偏差(即星站钟差)的准确性。为了解决上述问题,本文提出了一种基于抗差估计的多GNSS共视基准站融合星站钟差的方法。该方法利用中位数绝对值偏差(MAD)对星站钟差数据进行异常值检测,采用IGGⅢ等价权函数的抗差估计方法对多站的星站钟差数据进行融合,输出一组稳定的基准站参考值。通过Matlab仿真,对比MAD法和3-Sigma法的异常值检测性能,对于基准站星站钟差数据,MAD法更加适用。同时,将基于抗差估计的融合法与等权融合法进行对比,前者融合数据的标准差比后者下降0.11~6.65 ns,提高了系统的稳定性。

In order to meet the needs of remote time users for standard time UTC(NTSC)nanosecond distribution,a standard time remote reproduction system has been established.The single-reference terminal service model currently used in the system has certain risks.If the single receiver fails,it will affect the accuracy of the resulting deviation between local time and satellite clock(i.e.,the time difference between satellite time and local time).To solve the above problems,this paper proposes a method based on robust estimation for GNSS common-view multi-reference stations to fuse the time difference between satellite time and local time.In this method,the median absolute deviation(MAD)is used to detect the outliers of the time difference between satellite time and local time data,and the robust estimation method of IGG III.equivalent weight function is used to fuse the above data of multiple stations,to output a set of stable reference station reference values.Comparing the outlier detection performance of the MAD method and the 3-Sigma method through the Matlab simulation,the MAD method is more applicable for the time difference between satellite time and local time data of the reference stations.At the same time,the fusion method based on robust estimation is compared with the equal-weight fusion method,the standard deviation of the fusion data of the former is 0.11~6.65 ns lower than that of the latter,which improves the stability of the system.