Modeling and Assessment of BDS/GPS Triple-Frequency Precise Point Positioning

Beidou Navigation Satellite System (BDS), the first satellite navigation system with the capability of providing B1, B2 and B3 triple-frequency civil signals, can provide the services of positioning, navigation, and timing in the whole Asian-Pacific region and most of the world under current satellite constellation. With the modernization and upgrading of GPS, the number of GPS satellites with triple-frequency signals L1, L2, and L5 is also increasing. Currently, the precise point positioning (PPP) based on BDS and/or GPS is mainly adopting the B1/B2 and/or L1/L2 dual-frequency observations. To make full use of triple-frequency observations, this paper introduces a triple-frequency PPP model by using the raw observations of BDS/GPS. In this paper, three IGS (International GNSS Service center) stations’ data are adopted, and the data are processed with six modes: GPS dual-frequency PPP, GPS triple-frequency PPP, BDS dual-frequency PPP, BDS triple-frequency PPP, GPS + BDS dual-frequency PPP, and GPS + BDS triple-frequency PPP. Results illustrate that GPS + BDS dual-frequency PPP provides the shortest convergence time and the highest positioning accuracy compared to the other PPP modes. GPS + BDS triple-frequency PPP has a relatively longer convergence, and the positioning accuracy is slightly lower than GPS + BDS dual-frequency PPP. The main reason is that the satellite number of providing triple-frequency observations is much less than that of dual-frequency observations. The performance of BDS dual-frequency PPP is worse than that of GPS due to the lower accuracy of orbit and clock of BDS satellites. However, due to the less available number of GPS even cannot provide solutions when using triple-frequency observations, while BDS can offer centimeter-level positioning solutions.