一种低轨航天器与北斗卫星高精度时间传递方法及其初步试验验证

A method for high-precision time transfer between low earth orbit spacecraft and Beidou satellite and its preliminary test verification

低轨卫星系统近年来在空间目标探测、手机移动通讯、卫星导航系统增强、载人航天等方面都得到了快速发展和应用.我国载人航天工程近几年取得重大突破,在空间站设计搭载的高精度时频科学实验系统,预计可以建立日稳定度和不确定度在10^(-17)量级的空间时间频率基准.利用空间站精密时间信号向北斗卫星进行高精度时间传递,可以进一步提升北斗时间系统性能及北斗卫星自主时间维持能力.另一方面,我国北斗三号卫星导航系统具备全球组网星间链路功能,能够实现全星座的高精度定轨和时间同步.本文基于空间站和北斗卫星现有可用资源,提出一种基于双向测量方式的低轨航天器与中高轨卫星高精度时间传递方法.根据低轨航天器运行速度快等特点,给出相对高速运动环境下双向测量链路的运动时延误差修正方法.通过进一步建立仿真模拟平台、搭建真实天地试验场景等方式,对双向时间传递性能进行验证.仿真和试验结果表明,基于双向测量方式的低轨空间站与北斗卫星时间同步精度优于0.3 ns.本文可为实现天基高精度时频传递、空间站精密原子钟授时服务、提升北斗系统自主运行能力等提供理论和工程技术参考.

Recently,low earth orbit(LEO)satellite systems have been developed rapidly and have been applied in space target detection,mobile phone communication,satellite navigation system enhancement,and manned spaceflight.The China Manned Space Program has made noticeable progress.Chinese space stations have employed a high-precision time frequency scientific experimental system to establish a space time frequency reference with stability and uncertainty of 10~(-17)@day.This reference can further enhance the performance of the Beidou satellite(BDS)time system and the capability of autonomously time maintaining by transferring a high-precision time signal from the space station to the BDS.Meanwhile,the global networking inter-satellite link function of China's Beidou-3 navigation satellite system can achieve autonomous orbit determination and operation for the entire constellation.Based on the available resources of the space station,the BDS,and the two-way measurement method,a high-precision time transfer method for LEO spacecraft and medium-/high-orbit satellites is proposed.Given the characteristics of the high-speed operation of LEO spacecraft,a method for correcting the motion time delay error of the two-way measurement in a relatively high-speed motion environment is proposed.The performance of the two-way time transfer is verified by establishing a simulation platform and setting up a real-world test scenario.The results of the simulation and test show that the two-way time synchronization accuracy between the LEO space station and the BDS is better than 0.3 ns.This research can provide theoretical and engineering technology reference for realizing a space-based high-precision time frequency transfer,the precise atomic clock timing service based on space station,and enhancing the autonomous operation capability of the BDS.