A Self-time-keeping Synchronization System Based on Timing Drift Fitting Algorithm

Time and frequency transfer is widely used in synchronization system, where the real-time transmission link is built between two synchronization sites. However, the real-time link is not allowed to use in some synchronization application. To solve this problem that transmission link is not always active, a self-time-keeping synchronization system is proposed in this paper. In our system, we design an algorithm to fit the time drift between GPS and a local rubidium clock over a period of time. Based on the fitting algorithm, we control the clock to achieve the time synchronization without GPS time signal. A 24-hour time synchronization experiment was carried out with the system, and the experimental result shows that the root-mean-square (RMS) time drift is lower than 5 ns in one day.