Initial Assessment of Precise Orbit Determination for Combined BDS-2 and BDS-3 Satellites

By December 2019, twenty-four new-generation BeiDou (BDS-3) Medium Earth Orbit (MEO) satellites, three Inclined Geosynchronous Orbit (IGSO) satellites and one Geostationary Orbit (GEO) satellite have been launched, symbolizing its starting of global coverage.

The observations of a very limited number of 17 International GNSS (Global Navigation Satellite System) Monitoring and Assessment Service (iGMAS) stations and 80 IGS Multi-GNSS Experiment (MGEX) stations from October 2018 to October 2019 have been processed to determine the orbits of combined BDS-3 and BDS-2 satellites. All of the latest official BDS-2 and BDS-3 satellite phase center offsets (PCOs) and other satellite parameters were used in the data process. The internal consistency (daily boundary discontinuity) and satellite laser ranging (SLR) validations are conducted for the orbit validation. The average three-dimensional root-mean-square error (RMS-3D) of 24-hour overlapping arcs for BDS-2 and BDS-3 satellites is within 0.1m and 0.15m, respectively. Satellite laser ranging (SLR) validation reports that the orbit radial component for BDS-2 and BDS-3 satellites is within 0.1m. The orbit accuracy of BDS-3 is slightly lower than that of BDS-2 satellite presently.