| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a highly reliable inter-vehicle distance alarm system, by reducing influences of radio interference and of multi-path. SOLUTION: An actual inter-vehicle distance at a present point of time is computed as a distance an electromagnetic wave propagates in a period of time equating to a time difference between a time signal (in a signal processing part 30) by a clocking means possessed by an own vehicle and a time signal (received by a transreceiver 10) representing the same time and received from another vehicle, and an alarm is sent out when the actual inter-vehicle distance value is smaller than a predetermined safety inter-vehicle distance value. As for the frequency of the electromagnetic wave, a different frequency is allotted to every traffic lane by a frequency control signal produced by receiving and decoding a light signal received by a light receiver 20 and therefore radio interference is avoided. In order to prevent a time error from being produced between the two vehicles, a time reset signal is received by the light receiver and supplied to the signal processing part 30 and a time counter in the signal processing part 30 is reset with appropriate timing.</p> |
