导航星座自主时间基准的相对论效应

Effects of Relativity in Autonomous Time Reference for Navigation Constellation

从相对论框架下导航星座自主时间基准定义及其生成原理出发,对其实现要素进行了相对论分析及改正,包括卫星原子钟和星间链路测量量相对论效应,并以GPS、BDS为例计算说明。得出以下结论:1)卫星钟相对论常值由地面频率调整实现预修正,周期累积钟差则根据卫星星历实现实时计算和改正;在此基础上,2)星间链路伪距测量相对论效应主要是星间信号传播相对论效应,对中高轨卫星其最大影响为cm量级;3)星间链路多普勒测量相对论效应则是由卫星钟周期项频率变化引起,对小偏心率中高轨卫星而言,其对星间径向相对速度最大影响量在1 cm/s左右。分析结果有助于提高导航星座自主时间基准的准确度,并对深空测量和天基时间基准研究具有一定参考意义。

Beginning with the definition of autonomous time reference and its generation principle, the relativistic effects on the essential factors including satellite clock relativity and crosslink measurements relativity are analyzed in this paper, and calculated by taking GPS and BDS constellations for examples. The following conclusions are reached： 1 ） the satellite clock relativity effect has a constant part and a periodic part, and the constant part is compensated by terrestrial frequency adjustment, while the periodic clock error is corrected in real time according to the ephemeris ; on the basis of the adjustment of the satellite clock, 2） the crosslink pseudo-range （PR） measurement relativity effect between satellites inview is mainly the relativity effect on the light time delay, and can reach cm-level for medium and high orbits satellite ; 3 ） the crosslink Doppler measurement relativity effect is due to the period part of clock frequency offset, and its effect on radial velocity is around lcm/s for medium and high orbits satellite with small eccentricity. The above-mentioned analyses can help to improve the accuracy of autonomous time reference, and provide certain reference significance for the research of deep-space measurement and space-based time reference establishment.