| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a communication device for an automobile for discriminating whether a portable transceiver exists in the automobile or outside the automobile by exchanging a signal between the portable transceiver and a transmitting-receiving unit. SOLUTION: This communication device is composed of a portable transceiver 15 and a transmitting-receiving unit 10 having a first transmitting-receiving part 1, a second transmitting-receiving part 2, a control part 3 and a received signal judging part 4. The first transmitting-receiving part 1 is arranged in an outside part of an automobile. The other part including the second transmitting-receiving part 2 is arranged in a cabin of the automobile. The first transmitting-receiving part 1 and the second transmitting-receiving part 2 repeatedly transmit request signals different in time in a specific period. The portable transceiver 2 transmits an answer signal in response to reception of the request signals. The received signal judging part 4 discriminates the location of the portable transceiver 15 by judging the transmitting- receiving part receiving a high intensity answer signal when receiving the answer signal by the first transmitting-receiving part 1 and the second transmitting receiving part 2 to select a transmission carrier wave frequency of the request signal and the answer signal as a frequency lower than a cutoff frequency of a door window of the automobile.</p> |
