REPLICATING UTC(NIM) REMOTELY FOR TIME AND FREQUENCY TRACEABILITY

GPS time transfer is one popular method for remote comparison and calibration of time and frequency. In recent years, signals from new GNSS systems have become available. Through new GNSS systems, time and frequency transfer has been studied and implemented. Calibration uncertainties of the system for time and frequency have been evaluated as 6 ns and 2e-14 respectively averaging over one week. For the user who has no time scale or frequency standard, needs either or both of these and requires traceability to UTC(NIM), the Primary National Time and Frequency Standard of China, replicating UTC(NIM) could be a good way of meeting this requirement. We achieve this by providing a low-cost UTC(NIM) disciplined oscillator system with near real-time (16-minute latency) remote calibration through instant communication. We call this system NIMDO. Its performance have been verified and demonstrated referenced to UTC(NIM). NIMDO has been used at different sites and in several industries. The absolute values of the time and frequency differences from UTC(NIM) can be less than 1 ns and 5e-14 when averaged over one day, and the time and frequency stability can be better than 1 ns and 3e-14 respectively, averaged over one day.