Patent attributes
A keyless entry system includes a vehicle-side device and a portable device. The vehicle-side device includes a vehicle-side transmission unit connected to a plural transmission antenna and transmitting a request signal, and a vehicle-side reception unit receiving and transmitting an answer signal. The portable device includes a portable device-side control unit that detects the intensity of the signals transmitted from the plural transmission antennas. The vehicle-side control unit or the portable device-side control unit calculates distances between the portable device and the respective transmission antennas based on data of the intensity of the signals transmitted from the plural transmission antennas detected by the portable device-side control unit. When an added value of the distances calculated based on two of the intensity data is smaller than a predetermined threshold value, it is determined that the portable device is located inside the vehicle.
