Differential GPS Autonomous Failure Detection

Alison Brown, Janet King, Joseph Spalding

Abstract:	The U.S. Coast Guard is planning to use Differential GPS (DGPS) for buoy positioning. In the past, buoys have been positioned by the USCG through optical triangulation to visible landmarks. This procedure is time consuming and often results in significant delays when visibility is obscured by weather conditions. DGPS provides sufficient precision for locating buoys (10 meters 2dRMS) and will result in significant cost savings from more efficient use of USCG resources. Test results have demonstrated that DGPS can meet, and generally improve on, the accuracy requirement of 10 meters 2dRMS for buoy positioning. However, on occasion, transient errors are observed in the DGPS solution where, for short period of time, the positioning error exceeds the 10 meters requirement. Although these occurrences are infrequent in nature, the USCG requires a high level of confidence in the buoy location for safety requirements. DGPS errors can be caused by failures in the GPS satellites, transient errors in the DGPS Reference Station or errors introduced at the on-site receiver due to multipath or receiver failures. An algorithm is described in this paper which can be used to detect errors in the DGPS solution before they exceed the 10 meter threshold. The algorithm can be programmed into the remote DGPS Receiver and operates autonomously, using only data available in the DGPS navigation solution. The design of this DGPS Failure Detection algorithm is described in this paper and simulation results are presented to demonstrate its performance under different operating conditions.
Published in:	Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991) September 11 - 13, 1991 Albuquerque, NM
Pages:	521 - 536
Cite this article:	Brown, Alison, King, Janet, Spalding, Joseph, "Differential GPS Autonomous Failure Detection," Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991), Albuquerque, NM, September 1991, pp. 521-536.
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