On-orbit estimation of antenna phase center offsets for BDS-3 satellites

Accurate satellite phase center offsets (PCOs) are critical for high-precision GNSS data processing. Their pre-launch calibration and on-orbit estimation have long been essential tasks. For the third-generation BeiDou Navigation Satellite System (BDS-3), however, recent studies often derive PCOs from precise orbit determination (POD) using GPS L1/L2 receiver antenna calibrations and adjustable box-wing models for solar radiation pressure (SRP) modeling. Due to differing processing strategies, estimated BDS-3 PCOs vary across studies. Leveraging BDS-3 satellite metadata and BDS-specific receiver antenna calibrations, this study estimates BDS-3 satellite PCOs using long-term data. Results indicate that the X-offset obtained with an empirical SRP model combined with BDS-3 metadata is the most stable. Further analysis shows that the Z-offset is highly sensitive to the type of receiver antenna calibration model used. The relationship can be approximated as follows: a network-averaged bias in the receiver antenna up-direction causes a change of approximately −22.7 times in the MEO Z-offset for BDS-3-only POD, and −28.6 times for combined BDS/GPS processing. This finding aligns with prior studies, despite methodological differences, underscoring the importance of precise receiver antenna calibration. Validation experiments comparing the manufacturer’s model with the newer model show an average improvement of nearly 3% in the RMS of overlapping orbit differences. Additionally, static precise point positioning (PPP) experiments demonstrate coordinate improvements of about 5% for B1I/B3I and 14% for B1C/B2a signals compared to results using the manufacturer’s model.