Accuracy Assessment of Broadcast Ephemerides for Quasi-Zenith Satellite System

In this paper, we presented a method for assessing the broadcast ephemerides accuracy of QZSS by comparing the measured broadcast ephemerides with precise orbit and clock products provided by MGEX. By using this method, we carried out assessment of broadcast ephemerides for QZS-1 satellite and also compared the results with that of GPS system during the same data collection duration. The results show that: the broadcast ephemerides of QZSS can achieve an orbit accuracy of 0.42, 1.33 and 0.89 m in the direction of radial, along-track and cross-track and a clock accuracy of 1.87 ns respectively; the SISRE-orb and SISRE-orb&clk can achieve accuracies of 0.48 and 0.55 m respectively; currently the accuracy of broadcast ephemerides of QZSS still lags behind that of GPS system. The results presented in this paper may provide some reference information for multi-GNSS application in the near future.