Real-Time Carrier Phase Ambiguity Resolution for High-Dynamic Vehicles

To achieve real-time ambiguity resolution (AR) in a high-dynamic environment, an algorithm is needed that is robut to cycle-slips and requires the minimum possible number of consecutive measurements before correctly resolving the ambiguities. The problem with existing AR algorithms is that they require many consecutive measurements over a long period of time and/or a significantly changing satellite geometry. An innovative tehcnique is described which uses FDI equivalence and the optimal integer search space. The number of searches required to resolve ambiguities is significantly reduced over existing techniques. Furthermore, the technique of FDI equivalence is shown to be highly efficient in discarding false ambiguities. These two features of the proposed technique mean that when satellite visibility is good and measurement noise is low, the ambiguities can be resolved immediately after a single measurement from each channel. When visibility is reduced or noise is large, the technique can be enhanced to minimize the number of consecutive measurements required before the ambiguities are correctly resolved. The ambiguity resolution algorithm is designed to operate with an autonomous integrity algorithm developed by NAVSYS which produces a real-time check of the validity of GPS data. This algorithm is capable of performing real-time cycle-slip detection and repair. The performance of the ambiguity resolution algorithm will be enhanced and validated through simulation under the Phase I contract. Under Phase II a prototype system will be delivered for flight tests.