Patent ID: 9665121
Date: 2017-05-30
CPC Classifications: G06F,H04L

Claim:
1. A method for estimating the skew and offset of a slave clock in a slave device in relation to a master clock in a master device, the slave device and the master device being connected by a network, the method including the steps of: sending timing messages from the master device to the slave device over the network, each timing message passing through at least one peer-to-peer transparent clock; recording timestamps which are the times of the sending and receiving said messages according to the respective clocks; in each transparent clock, estimating the residence time of each message passing through the transparent clock and the propagation delay between the sending of the message by the previous transparent clock, or the master device if there is no previous transparent clock, and the receipt of the message by the transparent clock; estimating the total transit delay experienced by each timing message, using the total of all the residence times experienced in the transparent clocks and all of the measured propagation delays determined by the transparent clocks; communicating said total transit delay to the slave device; estimating the skew and offset of the slave clock using the said timestamps and said total transit delay; and synchronizing the output of the slave clock to the master clock using said estimated offset and skew; and wherein the step of estimating the skew and offset estimates the skew α as wherein: T T d