Conspiring Biases in the Local Area Augmentation System

Frank van Graas, Vignesh Krishnan, Rajesh Suddapalli and Trent Skidmore

Abstract:	This paper provides a theoretical analysis of the effect of conspiring pseudorange biases on aircraft position error. Biases conspire when they combine in such a way as to maximize their impact on the position error. The emphasis of the analysis is on the determination of the maximum allowable magnitude of conspiring biases that can be accommodated in the differential corrections broadcast by the Local Area Augmentation System (LAAS). In the paper, deterministic and random errors are treated separately to find a balance between their effects on the horizontal and vertical aircraft position errors. Closed-form expressions are provided for an unweighted least-squares position solution. A weighted position solution is analyzed using a computer simulation. The sensitivity of the aircraft position solution to conspiring biases is evaluated with respect to the number of satellites used in the solution, and constraints on the manner in which biases conspire. These constraints include biases on one or more satellites. The results presented in this paper provide a framework for the treatment of conspiring biases in high-integrity aircraft precision approach and landing systems.
Published in:	Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004) June 7 - 9, 2004 Dayton Marriott Hotel Dayton, OH
Pages:	300 - 307
Cite this article:	van Graas, Frank, Krishnan, Vignesh, Suddapalli, Rajesh, Skidmore, Trent, "Conspiring Biases in the Local Area Augmentation System," Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004), Dayton, OH, June 2004, pp. 300-307.
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