Patent ID: 8274374

Claim:
A synchronization method between a reader and a tag, wherein the reader comprises a reader clock, and wherein the tag comprises a tag clock, the method comprising: transmitting, by the reader, a first write command message to the tag at a first time of the reader clock; detecting, by the tag, the first write command message from the reader at a second time of the tag clock, and transmitting a first response message to the reader in response to the first write message; transmitting, by the reader, a second write command message including first time information of the first time to the tag; adjusting a time of the tag clock by a first value, wherein the first value equals the difference between the first time and the second time; transmitting, by the tag, a second response message in response to the second write command message at a seventh time of the tag clock; detecting, by the reader, the second response message from the tag at an eighth time of the reader clock and recording eighth time information of the eighth time in a memory region; transmitting, by the reader, a third write command message including the eighth time information to the tag at a ninth time of the reader clock; receiving, by the tag, the third write command message from the reader at a tenth time of the tag clock; and adjusting a time of the tag clock by a second value, wherein the second value equals one half of the difference between the seventh time and the eighth time.