A combination method for correcting satellite-based precise point positioning services on the user side

Abstract In recent years, several Global Navigation Satellite Systems (GNSSs) have begun offering free satellite-based Precise Point Positioning (PPP) services, including Galileo’s High Accuracy Service (HAS), BDS’s PPP-B2b, and Japan’s Quasi–Zenith Satellite System (QZSS) multi-GNSS advanced orbit and clock augmentation (MADOCA). In real-time positioning correction methods, individual services are prone to interruptions and anomalies. This study proposes combining multiple correction services to enhance correction availability and continuity from the user side, thereby fully leveraging observational data from various satellite positioning services. After detecting outliers in clock corrections and standardizing reference frames across services, a Kalman filter is employed to estimate the combined clock corrections. Since GPS is currently the only GNSS supported by these services, this study incorporates GPS correction data from Galileo’s HAS, BDS’s PPP-B2b and Japan’s QZSS MADOCA in a one-week experiment. By combining satellite-based correction products from different services, users can fully utilize GNSS corrections from each. This study demonstrates that combing corrections from multiple services significantly improves their availability and continuity. The average correction availability increased from approximately 75% for a single service to 99% for combined corrections. Static and simulated kinematic experiments at Multi-GNSS Pilot Project stations show that the combination strategy improves positioning accuracy by approximately 52.7%, 10.6% and 59.1% compared to PPP-B2b, MADOCA and HAS, respectively, with convergence time reductions of 48.5%, 37.1% and 67.1%. Marine experiment results with an unmanned underwater vehicle demonstrate that the combination strategy improves horizontal positioning accuracy by 19.7%, 59.1% and 17.8%, and vertical positioning accuracy by 54.1%, 77.8% and 1.2% compared to PPP-B2b, HAS and MADOCA.