The Impact of Operating GPS with More Rubidium Frequency Standards

David T. Crater, H. Shawn Mobbs

Abstract:	Over the history of the GPS program, Cesium frequency standards have carried most of the operational workload. On the Block II/IIA satellites, which carry two Cesium and two Rubidium frequency standards, the Air Force has activated 40 Cesium clocks, while only 15 Rubidiums have served as a satellite’s operational clock. There are sound reasons for this imbalance. However, as the Block II/IIA vehicles age, their Rubidium standards will by necessity begin to play a much larger role. Furthermore, the increasing number of Block IIR satellites, which contain only Rubidium clocks, will increase the impact of this dynamic. This paper focuses on the theoretical effects on GPS performance that will result from the activation of more Rubidium frequency standards. In particular, two strains of analysis are presented. The first is a study of the theoretical impact on satellite navigation accuracy. The second is an analysis of the impact to the GPS time-transfer mission, and by extension, to the GPS composite time scale.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	1713 - 1720
Cite this article:	Crater, David T., Mobbs, H. Shawn, "The Impact of Operating GPS with More Rubidium Frequency Standards," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1713-1720.
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