Performance Analysis of BDS-3 SAIM and Enhancement Research on Autonomous Satellite Ephemeris Monitoring

Integrity is one of the key indicators used to characterize performance global navigation satellite systems (GNSSs) and closely related user safety. In order realize real-time integrity monitoring, BeiDou Global Navigation Satellite System (BDS-3) has realized “satellite autonomous monitoring” (SAIM) function in its satellites for first time. BDS-3 SAIM monitoring functions signal power, pseudo-range, clock frequency phase, but not broadcast ephemeris. this study, long-term stability distribution characteristics data were analyzed by using actual telemetry The results show that have good basically follow a normal distribution, which meets design expectations. Meanwhile, view fact does ability independently monitor ephemerides, may lead over-tolerance probability risk risks active space environment, enhancement ephemeris proposed, integrates three relatively independent methods, with extrapolated from previous cycle, generated orbit determination, inter-satellite link distance measurement as reference data, respectively. methods are verified. each advantages disadvantages terms accuracy resource dependence. integration can combine their complementary also provide valuable an important engineering applications.