Putting a Number on GPS Integrity the IBM GPS Integrity Study for the DOD

Arthur G. Gower

Abstract:	The Global Positioning System (GPS) is coming of age, moving from a future utility to a present-day service. Although it has not yet been declared operational, the system is being used and is producing results exceeding expectations. If we look at the future role of GPS, one question emerges over and over again. Can we trust GPS and, if so, how much? Under direction from the Program Management Directive (PMD) dated 4 April 1990, the Department of Defense (DoD) tasked IBM to perform a study of GPS integrity. The study had two primary objectives. First, determine the level of integrity provided by the currently defined GPS, and second, determine the level of integrity provided by a proposed set of integrity enhancement systems (architectures). IBM has completed the GPS integrity study for the DoD and the results have been briefed to the General Officers Steering Committee (GOSC). This paper summarizes the significant aspects of the study. Areas discussed include: 1) The requirements and ground rules that were used. 2) The GPS Failure Modes and Effects Analysis (FMEA) that determined expected GPS failure rates and their effects on users. 3) The GPS integrity model that was developed to analyze the ability of a proposed architecture to provide a given level of integrity. 4) The existing and proposed integrity architectures that were analyzed in the study. 5) Results, conclusions and recommendations for enhancing the GPS.
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:	753 - 760
Cite this article:	Gower, Arthur G., "Putting a Number on GPS Integrity the IBM GPS Integrity Study for the DOD," Proceedings of the 4th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1991), Albuquerque, NM, September 1991, pp. 753-760.
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