The Effect of Selective Availability on Differential GPS Positioning

Brian W. Tolman, James R. Clynch, David S. Coca, Mark P. Leach

Abstract:	The effect of Selective Availability (SA) on differential positioning is considered, using an extensive two frequency P code data set which was collected during two periods: a publicly announced test of the GPS constellation in October. 1989. and after it was announced that SA had been implemented, in April 1990. The data were collected with the cooperation of several organizations, using TI 4100 receivers and atomic clocks at 6 sites, spanning baselines from 8 to 1350 kilometers, over a total of more than 25 days. A subset of this dataset shows strong characteristics which are probably due to SA. Differential positions which have been computed using this 'unhealthy' data are compared to truth positions, and to identically computed positions using apparently 'healthy' data from the same period. The results and their implications for the impact that SA could have on differential positioning are presented.
Published in:	Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990) September 19 - 21, 1990 The Broadmoor Hotel Colorado Spring, CO
Pages:	579 - 586
Cite this article:	Tolman, Brian W., Clynch, James R., Coca, David S., Leach, Mark P., "The Effect of Selective Availability on Differential GPS Positioning," Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990), Colorado Spring, CO, September 1990, pp. 579-586.
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