VEHICLE-MOUNTED COMMUNICATION SYSTEM AND VEHICLE-MOUNTED DEVICE

摘要

Provided is a vehicle-mounted communication system capable of reducing the time required for information communication between a vehicle-mounted device and a portable device for detecting the position of the portable device. The vehicle-mounted communication system is provided with: a vehicle-mounted device (1) that transmits a detection signal for detecting the position of a portable device (3) from a plurality of LF transmission antennas (22) fitted to a vehicle (C); and a plurality of portable devices (3) that receive the detection signal transmitted from the vehicle-mounted device (1) and that transmit a response signal corresponding to the received detection signal, wherein the vehicle-mounted device (1) detects the position of the portable devices (3) by receiving the response signal. The vehicle-mounted device (1) transmits a process start signal to be commonly received by the portable devices (3) from the plurality of LF transmission antennas (22) to the plurality of portable devices (3) continuously. The vehicle-mounted device (1) then transmits, after the process start signal, a detection signal to be commonly received by the portable devices (3) from the plurality of LF transmission antennas (22) continuously. Any of the portable devices (3) that has received the detection signal transmits to the vehicle-mounted device (1) a response signal including information corresponding to the detection signal transmitted from the vehicle-mounted device (1).