Analysis of the performance of the PPP-B2b satellite clock and its effects on time transfer

Abstract BDS-3 is capable of providing precise point positioning (PPP) services via B2b signals for the Asia–Pacific region. The performance of the satellite clock plays a dominant role in the transmission interval of B2b clock correction and PPP time transfer. In this work, first, the coverage of B2b signals is analysed, and the performance of the satellite clock is evaluated (including orbit accuracy, clock stability, clock accuracy and prediction accuracy). Second, the results of time transfer based on BDS-3 PPP-B2b are investigated. The values show that the orbit error of BDS-3 recovered from PPP-B2b is better than that of the GPS recovered from PPP-B2b. The stability of BDS-3 recovered from the PPP-B2b clock is superior to that of the GPS PPP-B2b clock. The stability of the BDS-3 clock is approximately 1∼2 e-13, 5∼9 e-14, and 3∼5 e-14 at 100 s, 1000 s, and 10000 s, respectively. No obvious discrepancy exists in the BDS-3 clocks of different types. The mean prediction accuracy of BDS-3 is 0.03 ns when the prediction time is up to 120 s, and the prediction accuracy of the GPS is 0.28 ns when the prediction time is merely 30 s. This result shows that it is possible to decrease the transmission interval of BDS-3 B2b clock correction and save much space. The time transfer based on BDS-3 PPP-B2b can subsequently achieve a 0.50 ns level. The frequency stability of the time link is approximately 9.25E-14, 2.42E-14, and 9.34E-15 at 100 s, 1000 s, and 10000 s, respectively. We can conclude that the BDS-3 PPP-B2b solution is reliable for time transfer.