IONOSPHERIC THREAT MODEL METHODOLOGY FOR WAAS

JUAN BLANCH, TODD WALTER, and PER ENGE

Peer Reviewed

Abstract: The ionosphere is the largest remaining error source affecting GPS. It also has some of the least predictable spatial and temporal variations. Consequently, the ionosphere becomes the determining factor in system performance for the Wide Area Augmentation System (WAAS). Because the ionosphere cannot be observed at all places simultaneously, the confidence bound, termed the grid ionospheric vertical error (GIVE), can be determined only with the aid of a threat model. The threat model is used to restrict the expected ionospheric behavior. A method is needed for accurately describing the limits of the threat model without being overly pessimistic. This paper describes a methodology for using real data to generate worst-case scenarios from which an appropriate threat model can be determined. This threat model must be coupled with a set of metrics that can distinguish wellobserved ionospheric regions.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 49, Number 2
Pages: 103 - 108
Cite this article: BLANCH, JUAN, WALTER, TODD, ENGE, PER, "IONOSPHERIC THREAT MODEL METHODOLOGY FOR WAAS", NAVIGATION, Journal of The Institute of Navigation, Vol. 49, No. 2, Summer 2002, pp. 103-108.
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