HY2D Satellite Onboard BDS-3 Data Quality Evaluation and Post-precise Orbit Determination Accuracy Analysis

Haiyang-2D (HY2D) satellite orbits with different arc lengths are determined based on BDS-3 (BeiDou-3) data collected from the onboard GNSS (Global Navigation Satellite System) receivers between July 7th and 16th, 2021 (day of year 188--197). The data quality of space-borne BDS-3 for HY2D satellites is analyzed from the aspects of satellite visibility, DOP (Dilution Of Precision) value, multipath effects. Meanwhile, the post-precise orbit accuracy is assessed using a number of tests, which include analysis of observation residuals, arc overlaps, orbit external-comparisons, and satellite laser ranging (SLR) residuals. The results indicate that: (1) Over 86.66% epochs with 4 BDS-3 satellites available. The multipath error RMS (Root Mean Square) for B1C frequency is about 0.37 m, and for B2a frequency, it is around 0.18 m. (2) Carrier phase fitting residuals range from 6 to 8 mm. The POD (Precise Orbit Determination) precision with only BDS-3 data is evaluated by overlap comparison, showing good orbit consistency at 2 cm level (3D RMS). As for external orbit validation, the radial RMS compared with the CNES (Centre National d'Etudes Spatiales) DORIS (Doppler Orbitography and Radio-positioning Integrated by Satellite) orbit is better than 1.9 cm. (3) The mean of SLR validation residual RMS is 3.24 cm. These results demonstrate that domestically-produced dual-frequency BDS receivers can meet the satellite's centimeter-level radial orbit determination requirements for altimetry satellites.