多站联合星地时间同步及预报性能分析

Performance analysis of multi-station combined satellites and ground time synchronization and prediction

无线电双向法通过上行与下行观测量比对实现星载钟与地面站时间同步,比对过程中消除或削弱了绝大多数的公共误差项,因此时间比对精度高。卫星不可视时该方法不能实施,此时卫星钟预报精度只能依赖卫星钟自身的物理性能,不可视弧长越长卫星钟预报精度衰减越快。为了削弱因卫星不可视带来的精度损失,多站联合星地时间同步是一种有效的解决方案。给出了多站联合星地时间同步的基本原理、推导了时间比对模型,并利用COMPASS实测数据分析了多站联合时间同步及预报性能,实验结果表明,多站联合观测有效延长了卫星的可视弧长,为提升卫星钟预报精度提供了数据基础。由于观测设备之间的系统性偏差,各站得到的星地钟差结果可能存在跳变,影响卫星钟预报精度。因此系统性偏差成为制约多站联合星地时间同步性能的关键性因素,系统性偏差的精确标定能确保多站联合星地时间同步及预报精度的大幅提升。

Two-way radio time synchronization can achieve high precise time comparison. The method doesn＇t work when the satellite is invisible. In order to weaken loss of precision due to satellites are not visible, time synchronization combined multiple stations is a good choice. This paper presents satellite time synchronization method combined multiple stations, its basic principle and the time comparison model are deduced, and the performance is analyzed with real observation data from COMPASS system. The experimental results show： the method can prolong the visible arc length effectively, which provides a data foundation for improving the prediction precision of the satellite onboard clock. As there are systematic deviations between observing devices, clock offset sequence may occur jump, which will affect the satellite clock prediction precision. Therefore, the systematic deviation becomes the key factor to effect synchronous performance for multi-station combined time synchronization, and the accurate calibration of systematic deviation can ensure a substantial increase for time synchronization and onboard clock prediction precision for multi-station combined time synchronization.