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卫星双向时间频率传递(TWSTFT)是我国北斗卫星导航系统(BDS)中实现地面站之间时间频率传递的重要方法.不同于通常的站间时频传递系统,BDS的一些地面站之间通过两颗地球静止轨道卫星实现了双TWSTFT独立比对链路.基于此双链路特征,我们之前的研究表明,通过有效分离钟差阿伦方差与测量噪声阿伦方差,可降低测量噪声对站间钟差频率稳定度评估(阿伦方差表示)的影响.本文在假设测量噪声为相位白噪声,钟差噪声为频率白噪声的情况下,推导给出了BDS双TWSTFT链路分离测量噪声阿伦方差获得的站间钟差阿伦方差置信区间的计算方法.对BDS实测数据分析表明,平滑时间=1 s时,通过双TWSTFT链路可获得的站间钟差的阿伦偏差(阿伦方差的平方根)的置信区间上限为3.2481012(置信度0.95).相比之下,通过单TWSTFT链路直接获得的站间钟差的阿伦偏差仅为(8.59–8.91)×1011(=1 s).本文结果进一步表明,利用两条独立比对链路,可以将测量噪声阿伦方差与钟差阿伦方差进行有效分离,从而减少测量噪声对钟差频率稳定度评估结果的影响.
TWSTFT is an important method to realize the time-frequency transfer between ground stations in China’s BeiDou satellite navigation system (BDS) .Different from the common station time-frequency transfer system, some ground stations of BDS pass two Based on this dual-link feature, our previous studies show that by effectively separating the clock-spread Allen variance and the measurement-noise Allen-Variance, the measurement noise can be reduced for the inter-station Clock frequency difference stability (Allen’s variance representation) .In this paper, assuming that the measurement noise is phase white noise and clock noise is frequency white noise, we derive the BDS dual TWSTFT link separation measurement noise Aaron Variance obtained by the method of calculating the inter-station clock difference Allan variance confidence interval.Based on the BDS measured data analysis shows that when the smoothing time = 1s, through the dual TWSTFT link can be obtained from the clock error of the station Allan deviation ) Is 3.2481012 (confidence 0.95). In contrast, the Aaron deviation of the clock error between stations obtained through a single TWSTFT link is only (8.59-8.91) × 1011 (= 1 s) The result of this paper It is further shown that by using two independent alignment links, the measurement noise Allen variance and the clock difference Allan variance can be effectively separated, so as to reduce the influence of measurement noise on the evaluation result of the clock frequency stability.