Monitoring the Remote Primary Clock by Using GPS Carrier Phase; Conference paper

摘要

TL has developed the new system for remote frequency calibrations by using the GPS carrier-phase observation. Remote sites can obtain the stability and accuracy of their frequency bases and the traceability to the TL frequency standard through the system. Since the GPS carrier-phase observation is more precise than the pseudorange measurement, we use it to estimate the frequency performance of a remote frequency source with respect to the TL frequency standard. Our system contains the master site installed at TL and the remote site installed at the customer. In the remote site, the signal from the remote frequency base is fed into the GPS receiver to replace its internal frequency. Hence, the frequency offset with respect to the GPS satellite clock can be obtained by performing the time difference (differences between two epochs) on carrier-phase observations. Under this circumstance, our system is able to monitor frequency performance at the real-time processing. At the master site, we set up the same GPS receiver at TL and performed the carrier-phase single difference (differences between two receivers at TL and the remote site) and time difference at the post processing. This extra system option can provide the traceability to TL and better system uncertainty. The data of remote sites can be sent to TL through the PSTN (Public Switched Telephone Network) or the Internet. We did some tests to verify the calibration system and the distance is about 270 km between the remote site and TL. In fact, the whole system is good to calibrate and monitor the frequency of the remote oscillator. The system stability is about 2 x 10(exp 11) per second and 6 x 10(exp -14) per day. Now, we have already installed the calibration system at the customers' sites, and provided calibration reports to them.