DEVICE FOR DETECTING THE INTRUSION OF A BODY IN A PREDETERMINED SPACE

The device comprises a transmitter (7) transmitting ultrasound into a predetermined space (5), a sensor (8) which senses the echoes from the transmission by the transmitter into the space in order to deliver a signal representative of the echoes, and electronic device for processing the signal in order to diagnose the possible presence of a moving body in the space (5). It further comprises a) device (10) for scanning the space (5) with the ultrasound beam output by the transmitter (7) and (b) device (11) for simultaneously moving the echo sensor (8) so as to optimize the signal/noise ratio of the output of the sensor (8).