BDS-3 Signal in Space Ranging Errors Performance and On-Orbit Status Monitoring and Evaluation Based on Historical Data from 2020 ~ 2022

Signal in Space (SIS) performance, particularly SIS Range Error (SISRE), is the core index for evaluating the navigation, positioning, and timing accuracy and integrity monitoring of the Global Navigation Satellite System (GNSS). In this research, the SISRE performance and on-orbit status of BDS-3 satellites are monitored and evaluated comprehensively based on the historical data composed of the broadcast ephemeris and observation data from IGS and iGMAS tracking stations from July 31, 2020, to May 31, 2022. The performance evaluation results show that the average accuracy of BDS-3 SISRE is 0.25 m, which is much better than the system design index. Based on the independent monitoring results, from the annual average of satellite on-orbit adjustment from 2020 to 2022, the overall operation of the system is good and tends to be stable. It is worth noting that the MEO satellite had two unplanned outages of satellite clocks whose health information was not updated or lagged in updating. Therefore, it is suggested that the system extensively use monitoring methods such as the inter-satellite link (ISL) and Satellite Autonomous Integrity Monitoring (SAIM) in the future to strengthen the worldwide monitoring of BDS-3 satellite on-orbit operation status.