| 摘要 |
<p>The device comprises a transmitter (7) of ultrasounds in a predetermined space (5), a sensor (8) sensitive to the echoes transmitted by the transmitter in said space for delivering a signal representing said echoes, and electronic means for treating said signal for detecting the possible presence of a moving body in said space (5). It further comprises a) means (10) for scanning the space (5) with an ultrasound beam coming from the transmitter (7) and b) means (11) for simultaneously displacing the echo sensor (8) so as to optimise the signal-to noise ratio of said sensor output. The invention is useful for protecting a motor vehicle against theft.</p> |
