Evaluation of carrier-phase precise time and frequency transfer using different analysis centre products for GNSSs

Abstract

The carrier-phase (CP) technique, based on the global navigation satellite system (GNSS), has proved to be a useful spatial tool for remote and precise time transfer. In this study, we analysed the performance of CP time and frequency transfer with different GNSSs, using a satellite orbit and clock products collected from three analysis centres (ACs): CODE, WHU, and GFZ. From the time and frequency transfer experiments with six international time links, we concluded that the CP technique, based on different GNSSs, can all achieve a sub-nanosecond level accuracy for time and frequency transfer. Statistical analysis of the experiments shows that the global positioning system (GPS) solution can obtain the mean root mean square (RMS) of the six time links: 0.321 ns for cod (satellite products of CODE), 0.347 ns for whn (satellite products of WHU), and 0.288 ns for gbm (satellite products of GFZ). For Russian global navigation satellite system (GLONASS) solutions, the mean RMS is 0.306 ns for cod, 0.371 ns for whn, and 0.298 ns for gbm. In terms of emerging GNSSs, the Galileo can achieve a mean RMS of 0.293 ns for cod, 0.356 ns for whn, 0.295 ns for gbm, and the BeiDou navigation satellite system (BDS) can achieve a mean RMS of 0.294 ns for cod, 0.333 ns for whn, and 0.303 ns for gbm. The mean RMS is 0.288 ns for GPS, 0.298 ns for GLONASS, 0.295 ns for Galileo, and 0.303 ns for BDS. Regarding the three ACs, cod and gbm solutions show better performance than whn solutions. With respect to the frequency stability of CP technique by different GNSSs, Galileo and BDS are comparable to GPS at different averaging time intervals, while GLONASS is significantly worse than GPS.