Alarm device for securing buildings and rooms

摘要

The device is used to secure building, closed rooms, etc. The device includes a central alarm control unit or alarm centre for receiving and processing electric alarm sensor signals and for controlling at least one alarm device. Also associated with the alarm centre (6) is an infrasound detector (18) responsive to the opening and closing of doors (20), windows (22) etc. of the building. This detector supplies electric output signals to be processed by the alarm centre (6). The detector (18) may be integrated into the construction of the alarm centre (6). It may have a mechanism for switching on and off independent of the other components of the alarm device. It may also have means for varying its sensitivity.