Acoustic glassbreak sensors use an omnidirectional microphone that hears the sound
of breaking glass. Some sensors even draw their electrical energy from the motion
of the breaking glass itself. They can also detect sudden shockwaves of a
breaking object such as glass or a door being kicked in. In this case, it is the
shockwave of the breaking glass, not the sound itself that is being detected.
Dual
technology sensors combine PIR and microwave infrared technology
to improve security effectiveness and to avoid false alarms. False alarms can
occur when normal occupants of a room drop a glass or drop something on the floor,
which could set off glassbreak alarms. Jingling keys or radio broadcasts
mimicking breaking glass may set them off as well. New glassbreak sensors are incorporating
additional infrared sensors which helps minimize the occurrence of
false alarms. |
