| 摘要 |
PROBLEM TO BE SOLVED: To provide an onboard machine capable of accurately deciding whether external equipment exists in the outside or inside of a vehicle compartment even when the external equipment is adversely affected by radio waves leaking out from an antenna disposed in a vehicle.SOLUTION: Among plural antennas disposed in a vehicle, one antenna is disposed so that radio waves propagate in a wider range in one of the outside or inside of a vehicle compartment than in the other one. An onboard machine transmits plural signals, which have different intensities, by selectively changing the plural antennas, and receives a receiving signal intensity, which is detected when the transmitted signal is received by the external equipment, from the external equipment. The onboard machine discriminates the location of the external equipment on the basis of a first receiving signal intensity and second receiving signal intensity. The first receiving signal intensity is a receiving signal intensity detected when the one antenna transmits a signal of a larger intensity than the other antennas do. The second receiving signal intensity is a receiving signal intensity detected when the other antennas transmit signals of larger intensities than the one antenna does. |
