北斗广域高精度时间服务原型系统

基于精密单点定位(precise point positioning,PPP)的时间传递技术以其精度高、覆盖范围广的优点成为性能最优的GNSS时间传递方法之一。随着广域差分产品时效性的提高,实时PPP时间传递开始应用于精密授时的研究。本文在PPP时间传递技术的基础上,结合实时卫星钟差估计、接收机时钟调控及硬件延迟标校技术,建立了基于北斗卫星导航系统(BeiDou navigation satellite system,BDS)的广域高精度时间服务(wide-area precise timing,WPT)系统,可为用户实时提供准确、稳定、可溯源的时间。WPT系统分为时间服务平台和用户终端两个部分。时间服务平台引入高精度的时间作为系统的参考时间基准,并提供广域实时差分改正数;用户终端基于实时PPP时间传递算法获取本地钟与系统时间基准的差异,并采用精密调钟技术实现终端与系统的同步。为了验证系统的实时授时性能,本文进行了零基线、短基线及广域环境下的性能测试和评估。试验结果表明,该系统零基线、短基线时间同步精度优于0.5 ns,广域条件下单天的授时精度均优于1 ns,为基于北斗系统的精密授时技术发展提供了参考。

BeiDou wide-area precise timing prototype system

In recent years, the time transfer method based on precise point positioning (PPP) shows a superior performance in terms of accuracy and coverage, which has made it become one of the most popular GNSS time transfer methods. As the timeliness of wide-area differential products improves, real-time PPP time transfer has been applied to the study of precise timing. On the basis of PPP time transfer, this paper introduces a wide-area precise timing(WPT) system based on BeiDou satellite navigation system (BDS). We applied real-time PPP time transfer, time-frequency control and hardware delay calibration technology in this system, which could ensure that users can obtain accurate, stable and traceable time in real time.The WPT system consisted of time service platform and terminal. The platform introduced high-accuracy time as the reference time of the system. At the same time, it provided real-time wide-area differential correction data. The terminal obtained the difference between the local clock and the system time based on PPP method. Then steering clock technology was used to realize time synchronization between terminal and system. In order to verify the real-time timing performance of the system, this paper conducted performance testing and evaluation in zero baseline, short baseline and wide-area environments. The experimental results show that the accuracy of time synchronization in the condition of zero baseline and short baseline is better than 0.5 ns. And timing accuracy in a single day is better than 1 ns in a single day, which provide a reference for the development of precision timing technology based on BeiDou system.