Body vibration detector for alarms - has inbuilt suppressor for environmental disturbance effects and permits abnormal sounds to pass through

摘要

A body vibration pick-up is used as the basis of an alarm system that is effective against burglary. The system is designed to provide capability for suppression of environmental disturbances. The signals from a pick-up (1) are amplified (3) and processed through a high pass fitter (4) (greater than 7 kH2). Signals are delayed (5) and used to trigger a threshold stage (6). The delay and threshold stages ensure elimination of environmental disturbances while allowing transients caused by explosion to have effect.