A Globally Efficient Means of Distributing UTC Time & Frequency Through GPS

John A. Kusters, Robin P. Giffard, Leonard S. Cutler, David W. Allan, Mihran Miranian

Abstract:	Time and frequency outputs comparable in quality to the best laboratories have been demonstrated on an integrated system suitable for field application on a global basis. The system measures the time difference between I pulse-per-second (pps) signals derived from local primary frequency standards and from a multi-channel GPS CIA receiver. The measured data is processed through optimal SA Filter algorithms that enhance both the stability and accuracy of GPS timing signals. Experiments were run simultaneously at four different sites. Even with large distances between sites, the overall results show a high degree of cross-correlation of the SA noise. With sufficiently long simultaneous measurement sequences, the data shows that determination of the difference in local frequency from an accepted remote standard to better than 1 x is possible. This method yields frequency accuracy, stability, and timing stability comparable to that obtained with more conventional common-view experiments. In addition, this approach provides UTC(USNO MC) in real time to an accuracy better than 20 ns without the problems normally associated with conventional common-view techniques. An experimental tracking loop was also set up to demonstrate the use of enhanced GPS for dissemination of UTC(USNO MC) over a wide geographic area. Properly disciplining a cesium standard with a multi-channel GPS receiver, with additional input from USNO, has been found to permit maintaining a timing precision of better than 10 ns between Palo Alto, CA and Washington, DC.
Published in:	Proceedings of the 26th Annual Precise Time and Time Interval Systems and Applications Meeting December 6 - 8, 1994 Hyatt Regency Reston Town Center Reston, Virginia
Pages:	235 - 254
Cite this article:	Kusters, John A., Giffard, Robin P., Cutler, Leonard S., Allan, David W., Miranian, Mihran, "A Globally Efficient Means of Distributing UTC Time & Frequency Through GPS," Proceedings of the 26th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, December 1994, pp. 235-254.
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