| Popis: |
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. |
