USNO Alternate Master Clock Steering

Steven T. Hutsell, Paul A. Koppang

Abstract:	The primary mission of the U.S. Naval Observatory (USNO) Alternate Master Clock (AMC) facility, located at Schriever AFB, is to back up the critical functions of the USNO Time Service Department in Washington, D.C. The USNO AMC operates two Master Clocks, AMC #I and AMC #2. Each one of these [Alternate] Master Clocks is ready to function as the nation’s source for precise time, UTC(USNO), should the need arise. This paper summarizes the current status of, and strategies used for, the steering of these Alternate Master Clocks. The various USNO AMC steering strategies utilize clock comparisons from Two-Way Satellite Time Transfer (TWSTT), GPS Common View (CV), and USNO AMC Timescale data. All current Alternate Master Clock steering strategies employ a combination of Kalman filtering and second-order control, first introduced into USNO operations in 1995. The respective designs for these steering strategies are based on several factors, including goals for synchronization and stability, as well as the desire for robustness and simplicity of operation. This paper analyzes the performance of these respective designs.
Published in:	Proceedings of the 32th Annual Precise Time and Time Interval Systems and Applications Meeting November 28 - 30, 2000 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	289 - 300
Cite this article:	Hutsell, Steven T., Koppang, Paul A., "USNO Alternate Master Clock Steering," Proceedings of the 32th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, November 2000, pp. 289-300.
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