Patent ID: 6101375
Filing Date: 2000-08-08
Classification: H04W

Abstract:
A method of interrogating a portable RF transceiver, comprising the steps of:providing an interrogator RF transceiver;providing a portable RF transceiver that is substantially smaller and lighter than the interrogator RF transceiver;the portable RF transceiver detecting whether it receives an interrogation RF signal;in response to receiving an interrogation RF signal, the portable RF transceiver transmitting a Response RF signal;the interrogator RF transceiver transmitting a first interrogation RF signal at a first power level;after transmitting the first interrogation RF signal, the interrogator RF transceiver detecting whether it receives said Response RF signal;if the interrogator RF transceiver does not detect that it has received said Response RF signal within a period of time following the transmitting of the first interrogation RF signal, the interrogator RF transceiver transmitting a second interrogation RF signal at a second power level that is higher than the first power level; andif the interrogator RF transceiver receives said Response RF signal from the portable RF transceiver, the interrogator RF transceiver transmitting additional signals to the portable RF transceiver at a power level which exceeds by a predetermined amount the power level value of the interrogation signal in response to which the portable RF transceiver transmitted said Response RF signal.