Time and Frequency Activities at the JHU Applied Physics Laboratory

Mihran Miranian, Gregory L. Weaver, Matthew J. Reinhart, and Richard A. Dragonette

Abstract:	The Time and Frequency Laboratory at the Johns Hopkins University Applied Physics Laboratory (JHL/APL) provides support to multiple current and upcoming NASA/APL missions that span our solar system from the study of the Sun’s coronal mass ejections to the examination of the outer planets and the Kuiper Belt objects. This support includes providing precise time and frequency to the integration and testing of new hardware, frequency reference for spacecraft ranging and communications via the APL satellite communications facility, and the time-stamping of ground-receipt telemetry packets from various spacecraft. The Lab’s ensemble of three high-performance cesium standards and three hydrogen masers are integrated to form the APL timescale, which is the basis for estimating UTC – UTC (APL) and for evaluating the performance of our clocks. Traceability to USNO, NIST, and UTC is maintained via GPS common-view and all-in-view time transfer. The Lab’s clocks are also incorporated into the computation of International Atomic Time (TAI).
Published in:	Proceedings of the 41st Annual Precise Time and Time Interval Systems and Applications Meeting November 16 - 19, 2009 Hyatt Regency Tamaya Resort Santa Ana Pueblo, New Mexico
Pages:	253 - 260
Cite this article:	Miranian, Mihran, Weaver, Gregory L., Reinhart, Matthew J., Dragonette, Richard A., "Time and Frequency Activities at the JHU Applied Physics Laboratory," Proceedings of the 41st Annual Precise Time and Time Interval Systems and Applications Meeting, Santa Ana Pueblo, New Mexico, November 2009, pp. 253-260.
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