| 摘要 |
An apparatus is proposed for monitoring a space exhibiting at least one window pane, especially an internal space. Its main components are at least two ultrasonic sensors (1, 1') for receiving signals produced when glass is breaking, at least one of which can be optionally operated as ultrasonic sensor (1). After a first ultrasonic sensor (1, 1') has been switched to transmitting mode, at least one other ultrasonic sensor (1, 1') is operated as receiver (1') for receiving ultrasonic signals emitted by the ultrasonic sensor (1) switched to transmitting mode. A sensor (1, 1') is switched from receiving to transmitting mode after at least one ultrasonic sensor (1, 1') has received a signal indicating breaking glass. <IMAGE> |
