Research On Primary And Backup Clock Synchronization Technology

With the development of China’s national economy and national defense construction andspace technology, the ever-increasing demands on accuracy, stability, reliability and continuityof the High-precision Time-frequency signal. Time-frequency signal is generated by the atomicclock. In order to ensure the reliability and continuity of the time-frequency signal, thetime-frequency systems are usually equipped with primary clock and backup clock. In normalcircumstances, time-frequency signal provided by the primary clock., when the primary clock isabnormal, the output signal replaced by the backup clock.In order to ensure the continuity andstability of output signal, primary clock and backup clock need to keep high-precisionsynchronization in the time-frequency system.This paper combines the needs of "XXX frequency subsystem to establish " project,researches the method how to keep high-precision synchronization between primary clock andbackup clock, builds the experimental platform and analysis the error, develops a software forphase consistency maintenance between primary clock and backup clock, and tests the accuracyand frequency stability of the output signal. The results show that: the system can reach targetsthat phase synchronization accuracy in real-time is less than1ns between two atomic clocks,and improve the long-term frequency stability of the output signal of the backup clock. Thesystem is also able to run stably for a long time. The main content of this paper include:(1) According to the principle of the system, build the experimental platform; design theprogress of the system.(2) By the error analysis of the system, method to reduce the error in the measurement isproposed, and accuracy of the time error in the measurement is improved.(3) According to the needs of the system, software to control frequency of the atomic clockis achieved, and frequency of the backup clock is controlled in cycle and automatic.(4) According to the needs of phase synchronization for primary and backup clock, methodbase on the state interval of atomic clock to control the frequency is proposed, and the methodis tested in different cycle. Test result show that: when to take the cycle to150seconds,7dayslater, real-time synchronization accuracy of the phase between primary and backup clock canreach requirements of±0.8ns, and the long-term frequency stability of the backup clock’soutput signal is improved effectively.