Signal Quality Analysis and Orbit Accuracy Verification of BDS-3

  Objectives  On July 31, 2020, China's BeiDou-3 satellite navigation system (BDS-3), which operates independently, has been fully completed and officially opened for service. The signal system of BDS-3 has been redesigned to provide public service signals of five frequencies: B1I, B3I, B1C, B2a and B2b.

  Methods  Based on the observations of international global navigation system monitoring and assessment service and multi-GNSS experiment (MGEX) tracking stations, this paper analyzes the characteristics of pseudoranges multipath error, signal to noise ratio, geometry-free ionosphere-free phase(GFIFP) combined observations of the new signal system, as well as the precise orbit determination (POD) performance evaluation of BDS-3 satellites.

  Results and Conclusions  The results show that the multipath noise level of BDS-3 satellites signal is better than that of BeiDou-2 navigation satellite system satellites, and there is no systematic deviation related to altitude angle, B1C is more significantly affected by multipath and noise. The GFIFP sequences of different signal combinations of BDS-3 satellites show periodic systematic error related to satellite, and the peak value is about 2 cm. For BDS-3 satellites, the one-step POD method is used. The two frequencies ionospheric free combination of B1I&B3I and B1C&B2a is adopted respectively. The orbit boundary discontinuity and satellite laser ranging carried out an orbit accuracy check, and the results show that when the number of available observations is less than B1I&B3I, the orbit accuracy of B1C&B2a is equivalent to that of B1I&B3I, and the radial internal coincidence accuracy is 6.1 cm and 6.6 cm respectively.