Abstract: BDS-3 is a global satellite navigation system independently built by China. Its performance level and performance comparison with other satellite navigation systems have an important impact on the follow-up promotion and application. In this paper, the signal in space range error (SISRE) is used as a key performance index of the system. Taking the multi-system precise orbit and clock offset provided by GFZ as the standard, the comparison and evaluation method of satellite orbit, satellite clock offset and SISRE is given. Based on the measured data of three months from January to March 2020, the accuracy improvement of BDS-3 relative to BDS-2 is verified, and the performance comparison between BDS-3, GPS, Galileo and GLONASS is analyzed emphatically. The results show that the accuracy level of BDS-3 is significantly higher than that of BDS-2 both in satellite orbit and in satellite clock offset. The orbit accuracy of BDS-3 in the R, T and N direction is 0.07 m, 0.30 m and 0.26 m respectively, which is at the optimal level among the four global systems. The satellite clock offset accuracy is 1.83 ns, which is basically the same as that of GPS, superior to GLONASS, but slightly worse than Galileo. In terms of the signal in space range error, if only orbit error is considered, BDS-3 SISRE(orb) is averagely 0.08 m. Next, Galileo SISRE(orb) is 0.26 m, GPS SISRE(orb) is 0.57 m, and GLONASS SISRE(orb) is 0.98 m. If the orbit and clock error are considered comprehensively, the average SISRE of BDS-3 is 0.50 m, which is slightly lower than 0.38 m of Galileo, better than 0.58 m of GPS, and significantly better than 2.35 m of GLONASS.

Key words: BDS-3, broadcast ephemeris, signal-in-space range error, satellite clock offset, accuracy evaluation