白燕, 卢晓春, 高天. 基于单点伪距归算的星间链路时间同步改进算法[J]. 武汉大学学报 ( 信息科学版), 2021, 46(7): 1044-1052. DOI: 10.13203/j.whugis20190256
引用本文: 白燕, 卢晓春, 高天. 基于单点伪距归算的星间链路时间同步改进算法[J]. 武汉大学学报 ( 信息科学版), 2021, 46(7): 1044-1052. DOI: 10.13203/j.whugis20190256
BAI Yan, LU Xiaochun, GAO Tian. An Improved Time Synchronization Algorithm on Inter-Satellite Link Based on Single-Point Pseudorange Epoch Conversion[J]. Geomatics and Information Science of Wuhan University, 2021, 46(7): 1044-1052. DOI: 10.13203/j.whugis20190256
Citation: BAI Yan, LU Xiaochun, GAO Tian. An Improved Time Synchronization Algorithm on Inter-Satellite Link Based on Single-Point Pseudorange Epoch Conversion[J]. Geomatics and Information Science of Wuhan University, 2021, 46(7): 1044-1052. DOI: 10.13203/j.whugis20190256

基于单点伪距归算的星间链路时间同步改进算法

An Improved Time Synchronization Algorithm on Inter-Satellite Link Based on Single-Point Pseudorange Epoch Conversion

  • 摘要: 北斗导航星间链路通过双向单程伪距测量,可以消除一部分信道误差,测量精度高,同时其Ka波段窄波束天线的灵活建链方式,使其在远距离高精度的时间同步以及其他空间航天器用户之间的时间同步方面具有很好的拓展应用价值。目前,导航星间链路时间同步方法主要依赖于卫星双方具备完整的星历信息,在具有较高运行速度且不能提供精确轨道信息的航天器等拓展用户的时间同步应用方面,导航星间链路常规算法受到一定的限制。提出了一种基于单点伪距归算的时间同步改进算法,给出了算法的基本原理和实现方式,分析了该算法对高速航天器位置精度的要求,通过仿真数据和实测试验数据分别对算法进行了验证,结果表明,基于单点伪距归算后的时间同步精度优于0.1 ns。该算法可拓展应用于低轨空间站以及深空探测器等高动态用户的时间传递。

     

    Abstract:
      Objectives  Inter-satellite link of BeiDou navigation constellation has better application value in remote time synchronization among space crafts because it can eliminate a part of channel error by dual-one way ranging method and it has a flexible link-building way. But current inter-satellite link system time synchronization method is highly depending on ephemeris parameters, and when one user has high orbital velocity and incomplete space position information, the conventional time synchronization algorithms are limited.
      Methods  This study is carried out mainly aiming at the application requirements of expanding users in navigation constellation inter-satellite link technique, and an improved dynamic delay correction method based on single-point pseudorange epoch conversion is proposed. The method only needs to synchronize the movement speed of one of the two sides and the position of both sides to correct the motion delay error. The advantage of this method is that the two-way time synchronization accuracy is not affected by one user's speed error with poor speed accuracy. In this paper, the basic theory and implementation method of the algorithm is given, and requirements to positional accuracy of spacecraft are analyzed. The algorithm is verified by simulation and test data.
      Results  From the simulation and test data analysis, this work could be classified some major clusters apparently: (1) By analyzing the requirement to the position accuracy of spacecraft in the course of time synchronization, the time synchronization accuracy between BeiDou-3 MEO (medium earth orbit) and spacecraft can arrive to 0.01 ns when the position error of spacecraft is less than 230 m, and the time synchronization accuracy between BeiDou-3 IGSO/GEO (inclined geosynchronous orbit/geostationary orbit) and spacecraft can arrive to 0.01 ns when the position error of spacecraft is less than 290 m. (2) By using single-point pseudorange epoch conversion method, the time synchronization accuracy between Beidou-3 M1 and spacecraft can arrive to 0.003 ns when the position error of spacecraft is 200 m and it has no velocity message. (3) By analyzing the inter-satellite link measuring data between BeiDou-3 M7 and Xi'an Ka ground station, the time synchronization accuracy between the satellite-ground is about 0.07 ns.
      Conclusions  This algorithm based on single-point pseudorange epoch conversion can solve the time synchronization with incomplete ephemeris parameters, and its time synchronization accuracy is better than 0.1 ns. This method also adapts to the precise time transferring among the low-orbit spaces and deep-space detectors.

     

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