Validation and evaluation on B1IB3I-based and B1CB2a-based BDS-3 precise orbits from iGMAS

Abstract

The quality analysis of precise orbit products are important for the BeiDou global navigation satellite system (BDS-3) to provide precise positioning, navigation and timing (PNT) services to users. The International GNSS Monitoring and Assessment System (iGMAS) is simultaneously been provided with B1IB3I-based and B1CB2a-based BDS-3 precise orbits since September 29, 2019. However, a comprehensive comparison and analysis of these two types of orbit products is still missing. In this contribution, we study the performance of these precise orbits by analyzing the day boundary discontinuity and Satellite Laser Ranging (SLR). Moreover, we compare these precise orbits with the BDS-3 orbit products from the multi-GNSS Experiment (MGEX) analysis center. The test period is more than two years from September 29, 2019 to October 21, 2021. We found that: First, compare them with the MGEX BDS-3 precise orbits provided by GFZ and WHU, the average root mean square (RMS) value of the position deviation in the 3D directions orbit component is 0.081 ∼ 0.154 m for MEO satellites and 0.202 ∼ 0.255 m for IGSO satellites. The ranks of different BDS-3 orbit consistency are MEO SECM > MEO CAST > IGSO and we observe that the orbit consistency in eclipse period is better than the ones in non-eclipse period expect for rare cases; Secondly, the RMS of SLR residuals is 5.0 ∼ 6.0 cm, and compared to the orbit in non-eclipse period, the decrease of orbit in eclipse period in percentage is 1.72%∼8.00%. In addition, the radial performance of B1IB3I-based precise orbits for MEO CAST satellites is better than that of B1CB2a-based precise orbits, but it is opposite for MEO SECM satellites; Thirdly, combine with the CODE’s new solar radiation pressure model, namely ECOM2, by using the day boundary discontinuity, the preliminary results illustrate that the average RMS value of the day boundary discontinuity for BDS-3 MEO satellites in the 3D directions orbit component is 0.546 ∼ 0.639 m, and it is 0.881 ∼ 0.897 m for BDS-3 IGSO satellites. The performance ranking of day boundary discontinuity of BDS-3 precise orbits in the 3D directions orbit component is B1IB3I-based MEO CAST > B1IB3I-based MEO SECM > B1CB2a-based MEO CAST > B1CB2a-based MEO SECM > B1CB2a-based IGSO > B1IB3I-based IGSO satellites.