Performance Evaluation of Spaceborne Atomic Clock for BDS-3 Basic System

At present, China’s BDS-3 basic system has been completed and started to provide global services. However, the accuracy of satellite clock difference seriously restricts the service performance of BDS, and the performance of satellite atomic clock directly determines the accuracy of satellite clock difference. To solve this problem, this paper studies and evaluates the performance of BDS-3 spaceborne atomic clock in detail. Based on the precision satellite clock data of BDS from August to October 2019, using the median method, this paper pre-processed the BDS-2 and BDS-3 data, and obtained the fitting residuals of the spaceborne atomic clock by using the polynomial fitting method. In addition, in the frequency domain, this paper studied and compared the periodic characteristics of spaceborne atomic clock of BDS-3 and BDS-2. The experimental results show that all the clock difference of BDS show significant periodic characteristics, and the main period of BDS satellite clock difference is 12 h and 24 h respectively, corresponding to 0.5 times, 1 times and 2 times of each satellite orbit period. Compared with BDS-2, the main period term of BDS-3 is clearer, more accurate and more stable. In addition, the experiment also shows that the period of satellite clock difference is different in different orbits and in the same orbit the periodic term of satellite clock difference is also different. The period term of BDS-3 is consistent with that of other MEO satellites. Finally, the performance analysis of BDS atomic clock shows that the performance of BDS-3 hydrogen atomic clock is better than that of BDS-2 atomic clock.