Patent ID: 8959381
Filing Date: 2015-02-17
Classification: G06F,H04J,H04L

Abstract:
1. A method of estimating the offset and skew of a local clock in a time client compared with a remote master clock in a time server, the method including the steps of: transmitting Sync and Delay Req messages under the IEEE 1588 PTP, carrying timestamps from the time server; receiving said messages at the time client and recording the time of receipt according to the local clock and extracting said timestamps; and performing a recursive estimation using a Kalman filter process based on the extracted timestamps and the output of the local clock to estimate the offset and skew of the local clock compared to the master clock, wherein the Kalman filter is applied to: the measurement equation: wherein: θ T T T T v and to the two-state dynamic model defined by: wherein: T w