PPP Range Error Integrity Using a Network of Ground Monitors

Autonomous vehicles would greatly benefit from a Precise Point Positioning (PPP) service that could support safety critical applications. This paper introduces an integrity monitor system that can provide the (pseudo)range error statistics, range error bias and standard deviation, from a centralized fault-tolerant PPP filter that based on Extended Kalman Filter (EKF). It can process measurements from multiple receivers at different locations.We consider the possibility of receiver faults for the integrity monitor, and form subsets of statistics using Solution Separation (SS) technique similar to Advanced Receiver Autonomous Integrity Monitoring (ARAIM). A robust error characterization is obtained from the subset solutions. As an application of this algorithm, we show that it is possible for geometric error to mask geometric-free error if a clock fault and an ephemeris fault occur at the same time, and how the test statistics from the central filter can successfully resolve this issue.. Finally, we used the fault-tolerant central filter to evaluate GPS fault on PRN-1 (SVN-63) on July 10th, 2023, and compute the robust range error statistics.