The Research On Integrity Of Wide Area Differential GPS System

Integrity performance is the key to assure the stringent safety requirements of flight, and to take GPS as the sole-means of civil aviation navigation. This paper focuses on the GPS integrity monitoring techniques, including Reciever Autonomous Integrity Monitoring (RAIM), Wide Area Augmentation System (WAAS) Integrity Monitoring. The problem relating to these techniques, such as system designation, theory, algorithms and so on, are studied systematically.The princinple of the integrity monitoring structure for WAAS is introduced. The core is focusd on the algorithms for User Differential Range Error (UDRE) and Grid Ionosphere Vertical Error (GIVE). UDRE is related to the status of satellites, including clock errors of satellites and ephemeris errors.And GIVE is mainly about ionospheric errors. Then the algorithm is tested by data of one day. For the lack of WAAS data, the algorithm is just studied to some extent.The extensive used RAIM algorithm is analysed in detail. There are two methods: least-square residual errors RAIM and parity vector RAIM. The corresponding failure-detecting and failure- excluding models are deduced. These two methods are testified to be equivalent in theory. Also, both methods are checked by actual data.In the end of this paper, Galileo integrity monitoring model and the theory of satellite automatic integrity monitoring are introduced. They are very different with current monitoring algorithms and are the goal of the new development.