Wang Wei, Yang Xuhai, Ding Shuo, Li Weichao, Su Hang, Wei Pei, Cao Fen, Chen Liang, Gong Jie, Li Zhi-Gang
IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Aug;65(8):1475-1486. doi: 10.1109/TUFFC.2018.2842094. Epub 2018 May 30.
Two-way satellite time and frequency transfer (TWSTFT) using satellites in inclined geo-synchronous orbit (IGSO) is fundamentally more difficult than using satellites in geostationary orbit (GEO), due to the fact that IGSO satellites are constantly moving relative to a ground station, which brings in large residual effects. In this paper, we designed a protocol and an algorithm to correct several factors that affect the precision of TWSTFT using IGSO satellites. We used two ground stations, each equipped with sending and receiving channels, to conduct real-time measurements of the distance and the speed of an IGSO satellite, and data collected were used to make appropriate corrections. We tested this concept by conducting TWSTFT experiments using an IGSO satellite (BEIDOU I1-S), and compared the results with that obtained using a GEO satellite (CHINASAT 12). Indeed, the individual components that contribute to the residual effects of TWSTFT measurements using the IGSO satellite were several orders of magnitude greater than that of the GEO satellite. By using our modified protocol, TWSTFT results with an IGSO satellite were well accorded with that of using a GEO satellite; the standard deviation of residuals was less than 0.4 ns, well within the limit for the measurement uncertainty of TWSTFT. Therefore, we have expanded the use of IGSO satellites for TWSTFT. In principle, it should also be applicable to medium earth orbit and other satellites.
使用倾斜地球同步轨道（IGSO）卫星进行双向卫星时间频率传递（TWSTFT），从根本上来说比使用地球静止轨道（GEO）卫星更具难度，这是因为IGSO卫星相对于地面站在持续移动，会带来较大的残余效应。在本文中，我们设计了一种协议和算法，以校正影响使用IGSO卫星进行TWSTFT精度的若干因素。我们使用了两个地面站，每个地面站都配备了发送和接收信道，对一颗IGSO卫星的距离和速度进行实时测量，并利用收集到的数据进行适当校正。我们通过使用一颗IGSO卫星（北斗I1-S）进行TWSTFT实验来测试这一概念，并将结果与使用一颗GEO卫星（中星12号）所获得的结果进行比较。实际上，使用IGSO卫星进行TWSTFT测量的残余效应中的各个分量比使用GEO卫星的情况大几个数量级。通过使用我们改进后的协议，使用IGSO卫星的TWSTFT结果与使用GEO卫星的结果吻合良好；残余的标准偏差小于0.4纳秒，完全在TWSTFT测量不确定度的限值范围内。因此，我们拓展了IGSO卫星在TWSTFT中的应用。原则上，它也应适用于中地球轨道卫星和其他卫星。
