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AvantGuard's Industry Glossary

Passive Infrared Motion Detector (Pir)

An alarm device that measures infrared (ir) light radiating from objects in its field of view to sense motion and activate an alarm. once the pir motion detector is installed, it settles into a normal state with a normal temperature. apparent motion is detected when an infrared source with another temperature, such as a human, passes in front of the pir detector and changes the normal temperature causing an alarm.