Accuracy Metrics for Judging Time Scale Algorithms

R.J. Douglas, J.S. Boulanger, C. Jacques

Abstract: Time scales have been constructed in different ways to meet the many demands placed upon them for time accuracy, frequency accuracy, long-term stability and robustness. Usually, no single time scale is optimum for all purposes. In the context of the impending availability of high-accuracy intermittently-operated cesium fountains, we reconsider the question of evaluating the accuracy of time scales which use an algorithm to span interruptions of the primary standard. We consider a broad class of calibration algorithms that can be evaluated and compared quantitatively for their accuracy in the presence of frequency drift and a full noise model (a mixture of white PM, flicker PM, white FM, flicker FM and random walk FM noise). We present the analytic techniques for computing the standard uncertainty for the full noise model and this class of calibration algorithms. The simplest algorithm is evaluated to find the average-frequency uncertainty arising from the noise of the cesium fountain's local oscillator and from the noise of a hydrogen maser transfer-standard. This algorithm and known noise sources are shown to permit interlaboratory frequency transfer with a standard uncertainty of less than 10^-15 for periods of 30-100 days.
Published in: Proceedings of the 25th Annual Precise Time and Time Interval Systems and Applications Meeting
November 29 - 2, 1993
Ritz-Carlton Hotel
Marina Del Rey, California
Pages: 249 - 266
Cite this article: Douglas, R.J., Boulanger, J.S., Jacques, C., "Accuracy Metrics for Judging Time Scale Algorithms," Proceedings of the 25th Annual Precise Time and Time Interval Systems and Applications Meeting, Marina Del Rey, California, November 1993, pp. 249-266.
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