Patent ID: 7420468

Claim:
A detector system for detecting an RFID tag having an RF antenna and being configured to transmit therefrom a signal containing a modulated carrier frequency impressed with an identification code, the detector system comprising: a presence detector having an interrogating antenna configured to transmit a carrier frequency; and wherein: the RF and interrogating antennae are coupleable to one another within a presence range; the RFID tag being configured to transmit a signal in response to the carrier frequency received from the interrogating antenna; the interrogating antenna being configured to receive a signal from at least one of the following: the signal transmitted by the RFID tag, signals transmitted by a combination of environmental noise and the RFID tag; the presence detector further including: a signal reader configured to receive the modulated carrier frequency from the RFID tag during a predetermined response time period for comparison to a reference level for determining the presence of the RFID tag within the presence range.