Patent ID: 8406257

Claim:
A method comprising: sending a first message from a first device to a second device, the first message including a value ST 1 indicating a current device time of the first device when the first message is sent from the first device to the second device: storing at the second device a value RT 1 indicating a current device time of the second device when the first message is received by the second device; sending a second message from the second device to the first device, the second message including a value ST 2 indicating a current device time of the second device when the second message is sent from the second device to the first device, the second message also including the values ST 1 and RT 1 ; storing at the first device a value RT 2 indicating a current device time of the first device when the second message is received by the first device; calculating at the first device a first time domain differential DIFF 1 between a time domain of the first device and a time domain of the second device using the values ST 1 , RT 1 , ST 2 and RT 2 ; and repeating the foregoing steps to calculate a plurality of values of the first time domain differential DIFF 1 ; and calculating at the first device an average of the maximum value of the plurality of values of the first time domain differential DIFF 1 and the minimum value of the plurality of values of the first time domain differential DIFF 1 .