Detection and Mitigation of Reference Receiver Faults in Differential Carrier Phase Navigation Systems

In this paper, a methodology is developed to evaluate differential carrier phase navigation architectures subject to reference receiver faults. Carrier phase measurements can be used to provide high accuracy estimates of a user´s position. But in applications that involve safety-of-life, such as in precision approach for autonomous shipboard landing, integrity also plays a critical role. One source of integrity risk is the potential for GPS reference receiver failure. Integrity risk in these situations is typically mitigated by equipping the reference station with redundant receivers. However, various approaches to utilize redundant carrier phase measurements from multiple reference receivers are possible. In this paper, we describe two new methods: an averaging approach where different position solutions are averaged in the position domain, and a coupled estimation approach where the measurements from all reference receivers are coupled in the range domain and used to estimate a unified position solution. Furthermore, we investigate the impact of using these methods on accuracy and integrity from several perspectives, including availability performance, cycle resolution capabilities, implementation complexity, and computational efficiency.