SPODS Software and Its Result of Precise Orbit Determination for GNSS Satellites

The Satellite Positioning and Orbit Determination System (SPODS) is a tool for data analysis of global navigation satellite systems such as GPS, BeiDou, GLONASS, and Galileo. It has being designed and developed at Xi'an Research Institute of Surveying and Mapping since 2011. A brief introduction of the main models and methods employed in SPODS was presented in this paper. Experiments of precise orbit determination for GPS and GLONASS as well as integrated orbit determination for multi-GNSS were carried out with observation data collected from IGS tracking network. Compared with IGS final orbit, the accuracy in RTN components are 0.008, 0.011 and 0.012 m for GPS orbits, and are 0.019, 0.047 and 0.054 m for GLONASS orbits. The rms of orbit arc boundary discontinuities in RTN components are 0.054, 0.135 and 0.204 m for Galileo satellites, and 0.203, 3.486 and 0.155 m for BeiDou GEO satellites, 0.093, 0.171 and 0.249 m for BeiDou IGSO satellites, 0.040,0.120 and 0.177 m for BeiDou MEO satellites. It's worth to notice that the accuracy of GPS orbit with SPODS is comparable with that of IGS Analysis Centers.