Realtime Identification and Mitigation of GPS SA Errors Using LORAN-C

Soo Y. Braasch

Abstract:	The hybrid use of Loran-C with the Global Positioning System (GPS) has been shown capable of providing a sole-means of enroute air radionavigation. By allowing pilots to fly direct to their destinations, use of this system is resulting in significant time savings and therefore fuel savings as well. However, a major error source limiting the accuracy of GPS is the intentional degradation of the GPS signal known as Selective Availability (SA). SA-induced position errors are highly correlated and far exceed all other error sources (horizontal position error: 100 meters, 95 96). Realtime mitigation and identification of SA errors from the position solution is highly desirable. This paper discusses how that can be achieved. The stability of Loran-C signals is exploited to identify SA errors and reduce their effects. A major advantage of this scheme is that a differential ground reference station is not required. Once the model for the SA has been identified, it can be used to predict SA during Loran outages. The theory behind this technique will be discussed and results using bench and flight data will be given.
Published in:	Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992) September 16 - 18, 1992 Albuquerque, NM
Pages:	1117 - 1123
Cite this article:	Braasch, Soo Y., "Realtime Identification and Mitigation of GPS SA Errors Using LORAN-C," Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992), Albuquerque, NM, September 1992, pp. 1117-1123.
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