Patent ID: 7068746

Claim:
A method of performing time synchronization between a clock master having a first clock and a clock slave having a second dock, said method comprising the steps of: (a) sending a first message to the clock master, the first message comprising information indicating a transmission time (“first transmission time”) of the first message; (b) receiving a second message from the clock master, the second message comprising information indicating a reception time (“first reception time”) of the first message and a transmission time (“second transmission time”) of the second message; (c) obtaining at the clock slave a reception time (“second reception time”) of the second message; (d) calculating a transmission delay between the clock slave and clock master from the first and second reception times and the first and second transmission times; (e) determining if the calculated transmission delay is within a time window; and (f) updating an accumulated delay with the calculated transmission delay if the calculated transmission delay is within the time window; wherein said window has a first and a second threshold, said thresholds are adjustable such that the window is a sliding window, the first threshold represents a best delay, the second threshold represents a maximum allowable difference from the best delay, and the best delay is a minimum calculated transmission delay; and wherein said step of determining if the calculated transmission delay is within the window comprises: determining if the calculated transmission delay is less than the best delay; and if the calculated transmission delay is less than the best delay; storing the calculated transmission delay as the undated best delay, discarding the calculated transmission delay, resetting the accumulated delay, and repeating steps (a)–(e) at least one further time.