An Evaluation of Various Space Clocks for GPS IIF

V. Nuth, W. A. Feess, C. Wu

Abstract:	This study projects the accuracy of GPS in the Accuracy Improvement Initiative (AII) environment given current satellite clocks and the future Block IIF cesium and rubidium clocks. AII is an upgrade to the GPS control segment that incorporates additional tracking stations and replaces the current partitioned filter with a fully correlated one. Real data, obtained during two weeks of October 1998, were modified when appropriate for simulated clocks. A simulation of the AII estimator is exercised on these data and its states used to predict user navigation messages, which are then compared to a truth reference. It is concluded that the IIF satellites, using either their cesium or rubidium clocks, would meet the AII accuracy spec@cation assuming one upload per satellite per 6 hours, but that the Block IIA satellites with their cesium clocks would not. An upload rate of once per day is possible only with the IIF Rb clock. Suggestions are made for improving estimator Performance.
Published in:	Proceedings of the 33th Annual Precise Time and Time Interval Systems and Applications Meeting November 27 - 27, 2001 Hyatt Regency Long Beach Long Beach, California
Pages:	55 - 62
Cite this article:	Nuth, V., Feess, W. A., Wu, C., "An Evaluation of Various Space Clocks for GPS IIF," Proceedings of the 33th Annual Precise Time and Time Interval Systems and Applications Meeting, Long Beach, California, November 2001, pp. 55-62.
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