| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication system including an on-vehicle device and a portable machine, and capable of determining the position or the moving state of the portable machine within the transmission range of a request signal transmitted from the on-vehicle device.SOLUTION: A key 16 as a portable machine measures, when it receives a request signal transmitted from an on-vehicle device 2, the RSSI of the request signal, and transmits a responce signal including the RSSI to the on-vehicle device 2. The ECU 3 of the on-vehicle device 2 determines, when it obtains at least three RSSIs of request signals transmitted from different transmitters, the position of the key 16 within a position detectable area in which the transmission areas of at least three transmitters overlap based on the RSSIs. The ECU 3 determines whether the key 16 is moving or stopped within the position detectable area based on the presence of the time-depending change of the RSSI, and continues the periodic transmission of the request signal when moving, and stops the periodic transmission when stopped.SELECTED DRAWING: Figure 1 |
