US Patent 8004400 Communication method for locating a parked vehicle

A method of locating a parked vehicle that is equipped with a RKE system including a vehicle-installed RF communication module and a driver-borne wireless RF nomadic device such as a key fob involves installing a RFID tag in the nomadic device and a RFID interrogator in the vehicle. The driver depresses a button on the nomadic device to transmit a location request to the vehicle's communication module, and the RFID interrogator in turn emits a RF interrogation signal to identify the RFID tag and determine its location relative to the vehicle. The communication module then transmits a compass bearing to the nomadic device, and an indicator of the nomadic device is activated to provide the driver with a bearing for locating the vehicle.