| 摘要 |
There are disclosed a method and a device for detection of the breaking of a pane of glass for delivery of an alarm signal. By means of a broad band ultrasonic sensor ultrasonic waves are detected, said waves being generated when a pane of glass is broken, an alarm signal being delivered upon receipt of ultrasonic waves within the frequency range of 50 - 110 kHz having amplitudes exceeding a predetermined threshold level. |
