The 2 SOPS Ephemeris Enhancement Endeavor (EEE)

Jeffrey D. Crum, Steven T. Hutsell, Ronald T. Smetek, Jr.

Abstract:	Historically, one of the main goals of the 2d Space Operations Squadron (2 SOPS) in maintaining the GPS constellation has been to achieve the best possible system accuracy. The Master Control Station (MCS) Kalman filter plays a key role in meeting this goal. Through a process known as tuning, the database values that control the Kalman filter operation are optimized to provide the best possible estimation and prediction. Over the years, a series of in-house efforts have dramatically improved the accuracy, reliability, and integrity of the GPS signal. The latest iteration of these efforts is called the Ephemeris Enhancement Endeavor (EEE). Air Force and contractor personnel have concentrated on two main areas as part of the EEE: Kalman filter tuning and deterministic models. Results of this effort demonstrate a 20% reduction in ranging errors and a 17% reduction in time transfer errors. The authors will present descriptions of each area investigated, explain how the new tuning parameters were derived, and provide detailed results of their efforts to date.
Published in:	Proceedings of the 29th Annual Precise Time and Time Interval Systems and Applications Meeting December 2 - 4, 1997 Sheraton Long Beach Hotel Long Beach, California
Pages:	117 - 130
Cite this article:	Crum, Jeffrey D., Hutsell, Steven T., Smetek, Ronald T., Jr.,, "The 2 SOPS Ephemeris Enhancement Endeavor (EEE)," Proceedings of the 29th Annual Precise Time and Time Interval Systems and Applications Meeting, Long Beach, California, December 1997, pp. 117-130.
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