Ph.D. Defense: Global Integrity Monitoring for Precise Satellite Navigation

Zoom Link: https://stanford.zoom.us/j/94875225861?pwd=aLU9u7DZW60qBbWWbDTr7Yh5rjUPzy.1

Meeting ID: 948 7522 5861 Passcode: 250988

Abstract: The Global Navigation Satellite System (GNSS) provides absolute positioning services to users based on radio signals transmitted by GNSS satellites. The most prominent and the pioneering GNSS service is the Global Positioning System (GPS) owned and operated by the United States government. While the typical GNSS service can provide meter level positioning accuracy, Precise Point Positioning (PPP) derived from utilizing corrections to these same measurements can achieve centimeter level accuracy for static receivers, and decimeter level accuracy for kinematic receivers. For any applications of PPP with safety-critical requirements, the integrity of the positioning result is crucial and thus needs to be also delivered for PPP to be trusted. This dissertation develops a ground-based integrity monitor for precise GNSS services such as PPP. It can monitor two of the most common and relevant satellite faults observed over the operation history of GPS. I demonstrate that the integrity monitor can track any type and any number of satellite clock and ephemeris faults in real-time while maintaining decimeter level accuracy and protecting the users anywhere on Earth. The monitoring results for several real satellite fault events are evaluated and shown to be bounded by the computed confidence bounds. The design, placement and selection of the receivers for the integrity monitor are formulated as a convex optimization problem that can optimally determine the best network design for a given number of monitoring receivers. In particular, I address the questions about where to place the receivers and how many of the receivers are required to obtain the desired level performance. Together, these results describe the first complete global high-integrity ground-based monitoring system to protect users against satellite clock and ephemeris faults while providing decimeter level accuracy and meter level confidence bounds. This is an order magnitude lower than similar system such as Wide Area Augmentation System (WAAS) can provide.