TIME SCALE ALGORITHM: DEFINITION OF ENSEMBLE TIME AND POSSIBLE USES OF THE KALMAN FILTER

Patrizia Tavella, Claudine Thoinas

Abstract:	The work reported in this paper takes place in a general theoretical overview concerning the generation of an ensemble time scale. Different algorithms can be designed to match the particular needs of users and the available sets of clocks and time measurements. In all cases however, the statistical treatment of clock data requires at least: • the definition of an average time scale, • the specification of a procedure to optimize the contribution of each clock, • the implementation of a filter on each cock frequency to provide a means of prediction. Here, the comparative study of two time scale algorithms, devised to satisfy different but related requirements, is presented. They are ALGOS (BIPM), producing the international reference TAI at the Bureau International des Poids et Mesures, and ATI (NIST), generating the real-time time scale ATI at the National Institute of Standards and Technology. In such case, the time scale is a weighted average of clock readings, but the weight determination and the frequency prediction are different because they are adapted to different purposes. The possibility of using a mathematical tool, such as the Kalman filter, together with the definition of the time scale as a weighted average, is also analysed. Results obtained by simulation are presented.
Published in:	Proceedings of the 22th Annual Precise Time and Time Interval Systems and Applications Meeting December 4 - 6, 1990 Sheraton Premiere Hotel Vienna, Virginia
Pages:	157 - 170
Cite this article:	Tavella, Patrizia, Thoinas, Claudine, "TIME SCALE ALGORITHM: DEFINITION OF ENSEMBLE TIME AND POSSIBLE USES OF THE KALMAN FILTER," Proceedings of the 22th Annual Precise Time and Time Interval Systems and Applications Meeting, Vienna, Virginia, December 1990, pp. 157-170.
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