| 摘要 |
<p>In a malfunction detection mode, a controller is configured to compare an output of a phase-detector obtained when controlling to input an oscillation signal to only the phase-detector, with an output of the phase-detector obtained when controlling to input the oscillation signal to both of a transmitter and the phase-detector. If a change (difference) of signal levels of the outputs is equal to or more than a prescribed threshold, the controller determines that there is no malfunction in the transmitter and a receiver. If the change of the signal levels is less than the prescribed threshold, the controller determines that there is a malfunction in the transmitter or the receiver. Therefore, unlike a conventional moving body detector, it is possible to detect presence or absence of malfunction occurrence with only one kind of the oscillation signal, and accordingly achieve addition of a malfunction detection function, while suppressing increase in the cost or the size.</p> |
