Patent ID: 8289129

Claim:
A method for locating Radio Frequency Identification (RFID) tags, said method comprising: a passive RFID tag A receiving a polling command previously transmitted from a RFID reader and addressed to another passive RFID tag B; said RFID tag A determining that the polling command is not addressed to the RFID tag A; in response to the RFID tag A determining that the polling command is not addressed to the RFID tag A, at a time t 1 said RFID tag A setting the RFID tag A to a catching mode configured to catch echos from other tags; said RFID tag A receiving at a time t 3 an echo of a message sent by the RFID tag B to the RFID reader in response to the polling command received by the RFID tag B at a time t 2 , wherein the echo comprises an identification of the RFID tag B, and wherein t 3 >t 2 >t 1 ; said RFID tag A determining a distance (D.t 2 t ) between the RFID tag A and the RFID tag B based on a total timing (TT) equal to t 3 minus t 1 ; said RFID tag A ascertaining that the distance D.t 2 t does not exceed a specified radius limit; and responsive to said ascertaining, said RFID tag A storing the identification of the RFID tag B and the distance D.t 2 t in a database within the RFID tag A.