Tracking and data quality analysis of BDS-3 satellites from the global network

In view of the large differences and changes in the number of tracking satellites used by tracking stations for Beidou-3 Global Navigation Satellite System and the uneven quality of the observation data, the global network observation data is based on three major open datasets, namely, the International GNSS Service (IGS) Tracking Network, the European Reference Framework (EUREF) Tracking Network and the Australian Geological Sciences Agency (GA) Continuous Operations Tracking Network. The number of satellites receiving different BDS-3 signals and the change of maximum PRN number for each tracking station during the year since BDS-3 was officially opened are analyzed. The quality of one month’s observation data of 473 tracking stations is evaluated based on four indicators: data integrity rate, cycle skip ratio, code pseudo-range multipath error and number of visible satellites. The results showed that as of 31 July 2021, 223, 516 and 142 tracking stations can receive B1C/B2a, B1I/B3I dual-frequency and B2b observations in the above-mentioned global network, of which 97.8%, 70.2% and 99.3% can receive at least 18 BDS-3 satellites, respectively. Receiver and firmware versions capable of receiving all BDS-3 satellites mainly include JAVAD TRE_3/3.7.10, TRIMBLE ALLOY/5.44/5.45, SEPT ASTERX4/4.8.2, SEPT POLARX5/5.4.0, LEICA GR30/4.50/7.710, LEICA GR50/4.50.274, STONEX SC2200/2.12-210201, CHC P5E/1.2.5RUS. Among the 473 tracking stations, 71% have 100% data integrity, 64.1% have no more than 1 cycle-slip ratio (CSR), and 90.7% have 0.2-0.6 m pseudo-range multipath error. 208 tracking stations capable of receiving B1I/B3I dual-frequency signals and 134 tracking stations capable of receiving B1C/B2a dual-frequency signals were selected with better data quality. The results can serve as references for BDS-based navigation, positioning and timing (PNT) service.