Synchronizing computer clocks using Kalman filters

Abstract

I have used the Kalman Filter algorithm to improve the link between the Internet Time Servers operated by the National Institute of Standards and Technology (NIST) and the primary atomic clock ensemble in Boulder, which realizes UTC(NIST) and which is used as the reference for the time servers. The Kalman algorithm is better able to separate the contributions of multiple noise sources such as the fluctuations in the asymmetry of the channel delay and the statistical fluctuations in the clock used as the internal reference for the time server. This improved separation has made it possible to compensate to some extent for the lower-quality telephone circuits that are often used as the links for synchronizing the time servers to the atomic clock ensemble.