A study of the NBS time scale algorithm
Open Access
- 1 April 1989
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Instrumentation and Measurement
- Vol. 38 (2) , 631-635
- https://doi.org/10.1109/19.192364
Abstract
A study is made of the various aspects of the algorithm theoretically, comparing the NBS (US National Bureau of Standards) algorithm with a Kalman filter to discuss questions of optimality. It is shown that since the time of a clock is not measured, but only the time difference between clocks, a time scale should not attempt to optimize time accuracy, since that has no meaning. However, time uniformity and frequency stability can be optimized. The authors further study the practice of monitoring the clocks in a time scale for frequency steps, and removing a clock from the scale when a step has been detected until the new frequency is learned. The authors show that the effect of this practice on the algorithm is to translate random walk behavior in the individual clocks, due to the frequency steps of the clocks, to flicker noise for the ensemble. The implication is that careful monitoring of the scale can significantly improve its long-term performance.<>Keywords
This publication has 3 references indexed in Scilit:
- The effect of humidity on commercial cesium beam atomic clocksPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2003
- An NBS calibration procedure for providing time and frequency at a remote site by weighting and smoothing of GPS common view dataIEEE Transactions on Instrumentation and Measurement, 1987
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