BDS-2卫星钟设计年限末期阶段性能评估与分析

Performance Evaluation and Analysis of the Final Stage of BDS-2 Satellite Clock Design Period

为探究BDS-2卫星钟在当前阶段的运行状态及性能情况,采用国际GNSS监测评估系统(iGMAS)2018年共365 d的精密钟差数据,将Score检验量引入钟差异常探测,并结合中位数法进行数据质量控制,弥补了中位数法部分粗差漏探的缺陷;再从频率准确度、频率漂移率、频率稳定度、模型拟合残差、周期特性、噪声类型等6个方面对BDS-2卫星钟的相关性能进行全面评估。结果表明,现阶段BDS-2在轨卫星钟的运行状态良好,各项性能指标均正常,可继续提供相应的系统服务。其中,BDS-2卫星钟的频率准确度为3.15×10^-11,日漂移率为1.59×10^-13,万秒稳为5.72×10^-14,模型拟合残差平均精度为0.596 ns;GEO、IGSO和MEO三类卫星的钟差序列周期特性显著,第1、2主周期与其各自卫星轨道周期相关,分别为其轨道周期的0.5倍或1倍左右;不同平滑时间下的BDS-2卫星钟主要受调频白噪声(WFM)、调频闪烁噪声(FFM)和调频随机游走噪声(RWFM)的影响。

In order to explore the operating status and performance of the BDS-2 satellite clock at this stage,based on the 365 days of precision clock offset data from the international GNSS monitoring and assessment system(iGMAS)in 2018,this paper introduces the Score test into the clock offset detection and combines the median method to control the data quality,making up for the gross error defect of the median method.Then,from the six aspects of frequency accuracy,frequency drift rate,frequency stability,model fitting residual,period characteristics and noise type,we comprehensively evaluate the relevant performance of BDS-2 satellite clock.The results show that:at this stage,the BDS-2 on-orbit satellite clock is in good operating condition,all performance indicators are normal,and the corresponding system services can continue to be provided.Among them,the frequency accuracy of the BDS-2 satellite clock is 3.15×10^-11;the daily drift rate is 1.59×10^-13;the frequency tens of seconds stability is 5.72×10^-14;the average accuracy of the model fitting residual is 0.593 ns;the GEO,IGSO,and MEO three types of satellite clock data have significant periodic characteristics,and the first and second main periods are related to their respective satellite orbit periods,which are about 0.5 times or 1 times their orbital periods respectively;the BDS satellite clock noise types are basically the same under different smoothing times,and are affected by WFM,FFM and RWFM.