Global Positioning System (GPS) Advances in Autonomous User System (Norway Demonstration)

M. P. Ananda, H. Bernstein, W. A. Feess, R. C. Kells, J. H. Wortham, T. C. Paugstat

Abstract:	A GPS autonomous navigation system will be operational with the GPS Block IIR satellites in the first decade of the twenty-first century. This system will provide the user with full navigation accuracy for 180 days even if the GPS Operational Control Segment (OCS) is inoperable. Until such a system is operational, GPS navigation accuracy depends on a functioning OCS. If the OCS fails, the navigation accuracy degrades rapidly. To provide interim full-system accuracy in the event of loss of the OCS, an Autonomous User (AU) System, requiring user segment modification only, has been designed, implemented, and field tested. A previous paper presented system concepts and field test results in Yuma, Arizona, Washington, D.C., and Australia. In this paper, the results of using a new AU algorithm extended the AU System concept by allowing use of a crystal frequency reference instead of an atomic reference. Results with both crystal and atomic frequency references are presented. A system demonstration was accomplished in Tromso, Norway during the Summer of 1988. The results obtained indicate that in the 180 day period, the autonomous user with a crystal reference can achieve a navigation accuracy of the same order of magnitude as when the OCS is functioning. The AU System concepts are also applicable to other navigation systems.
Published in:	Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989) September 27 - 29, 1989 The Broadmoor Hotel Colorado Spring, CO
Pages:	425 - 437
Cite this article:	Ananda, M. P., Bernstein, H., Feess, W. A., Kells, R. C., Wortham, J. H., Paugstat, T. C., "Global Positioning System (GPS) Advances in Autonomous User System (Norway Demonstration)," Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989), Colorado Spring, CO, September 1989, pp. 425-437.
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