| 摘要 |
A method of passive response communication, especially for an access control system, in which a first transponder ( 2 ) transmits an interrogation signal to a remote second transponder ( 3 ), which responds by transmitting data back to the first transponder ( 2 ), the two transponders each comprising a transmitter and a receiver, and a communication signal exchanged between said transponders ( 2, 3 ) in at least one direction including a plurality of anti-relay-attack pulses ( 13, 14 ). At least one distinguishing pulse ( 14 ) selected among the anti-relay-attack pulses has a distinctive shape and the receiver of said communication signal is selectively responsive to the shapes of said plurality of pulses ( 13, 14 ). Interception of the transmitted signal in a relay attack using digital transceivers will not relay the distinctive shape and the response of the second transponder is inhibited.
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