Patent ID: 7751957

Claim:
A method of determining a position of a portable device in a keyless entry system apparatus comprising a vehicle device including a vehicle transmitter having a plurality of transmitting antennas that is provided in a vehicle and transmits a request signal; a vehicle receiver that receives an answer signal; a portable device having a portable receiver that receives the request signal; and a portable transmitter that transmits the answer signal, wherein the vehicle device has a vehicle controller that performs a predetermined control when the answer signal from the portable device is verified, and the portable device detects the intensity of each signal transmitted from the plurality of transmitting antennas of the vehicle device of the vehicle, and has a portable controller which transmits information on the detected intensity to the portable transmitter of the portable device, and wherein the vehicle controller has a memory, the method comprising the steps of: storing, in the memory in advance, an inside data group having information on the intensity of signals transmitted from the plurality of transmitting antennas of the vehicle when the portable device is positioned along the inside of the vehicle, and an outside data group having information on the intensity of signals transmitted from the plurality of transmitting antennas of the vehicle when the portable device is positioned along the outside of the vehicle, and determining whether the information on the intensity of signals received by the portable device is closer to the inside data group or the outside data group stored in the memory by the vehicle controller, the signals being transmitted from the vehicle.