Development and integrity evaluation of a real-time precise point positioning augmentation service based on characterization of phase residuals

In recent years, precise point positioning (PPP) technology has undergone rapid development. In particular, since the International GNSS Service (IGS) began providing multi-system real-time products, real-time PPP has been widely applied in areas such as displacement monitoring, atmospheric sounding, and geodetic surveying. Although real-time products generally demonstrate stable performance and meet application requirements under most conditions, anomalies in the real-time product are inevitable. These anomalies include low product availability, degraded accuracy, and even abnormal results. Currently, several IGS analysis centers provide real-time products; however, none of them include corresponding integrity information. In this study, we first developed a real-time PPP augmentation service, which utilizes globally distributed tracking stations to determine satellite orbits, clocks, and uncalibrated phase delays (UPDs). Furthermore, this study provides a detailed analysis of integrity information, such as quality indicators (QI) for each system based on characterization of phase residuals. Finally, validation of the real-time PPP augmentation system using 24 globally distributed stations demonstrates average positioning accuracies of 0.012 m, 0.014 m, and 0.031 m in the North, East, and Height components, respectively, with an average convergence time of 129 s and a wrong-fix rate of 2.225%. The results indicate that under nominal service conditions, integrity information has minimal impact on positioning accuracy, though it slightly reduces the probability of wrong-fix rate and the time-to-first-fix (TTFF). However, during satellite orbital maneuvers or periods of degraded accuracy and anomalies, QI significantly enhances both positioning precision and solution reliability.