Patent ID: 8749354

Claim:
An RFID system comprising: an antenna configured to send a transmission signal to an RFID tag in an RF environment and to receive a receiving signal transmitted from the RFID tag; an isolator configured to isolate the transmission signal and the receiving signal; a reader controller; a controller separate from the reader controller and configured to: output the transmission signal to be transmitted to the RFID tag when a transmission command signal is received from the reader controller; read the receiving signal transmitted from the RFID tag; and transmit tag information read from the receiving signal to the reader controller; a leakage signal canceller configured to receive the receiving signal including a transmission leakage signal and a portion of the transmission signal, wherein the leakage signal canceller comprises: a first leakage signal canceller configured to perform an adjustment task including generating a cancellation signal according to an adjustment value to cancel the transmission leakage signal from the receiving signal; and a second leakage signal canceller configured to perform the adjustment task and output the receiving signal without the transmission leakage signal to the reader controller after the adjustment task is performed; wherein the reader controller is configured to: determine whether there is a change in the RF environment using an intensity of the receiving signal directly received from the leakage signal canceller during a preset period; detect the adjustment value that results in the intensity of the receiving signal being less than a reference value; transmit the adjustment value to the leakage signal canceller when there is a change in the RF environment; cause the leakage signal canceller to cancel the transmission leakage signal from the receiving signal according to the change in the RF environment using the adjustment value; repeatedly determine whether the intensity of the receiving signal output by the second leakage signal canceller is equal to or greater than the reference value, redetect the adjustment value, and cause the second leakage signal canceller to perform the adjustment task with the redetected adjustment value until the intensity of the receiving signal is less than the reference value; cause the first leakage signal canceller to perform the adjustment task using the redetected adjustment value to generate the receiving signal without the transmission leakage signal, and transmit the receiving signal without the transmission leakage signal to a receiving amplifier; and cause the controller to read the receiving signal without the transmission leakage signal that is transmitted from the receiving amplifier.