PIR Basics – Tech Talk #7

A very important part of each Videofied camera is the PIR (Passive Infrared Motion) detector. It is this detector that triggers the camera to record the 10 second video so let’s talk about PIR characteristics that we can take advantage of and also avoid when placing each camera.

PIR’s are most sensitive to detecting a human moving across the field of view and far less sensitive to detecting a person if they are moving directly toward or away from the PIR. You can test this yourself from the Maintenance Menu by selecting Functional Test Devices which turns on the “walk test” mode. Try walking directly toward the MotionViewer camera starting 50 feet away. You will see that you can cover a lot of ground, maybe 25 to 30 feet before the PIR red LED will finally illuminate indicating an alarm. Then do the same thing but this time walking across the detection area so the camera is on your right or on your left. You will see the red LED illuminate after only a few steps! Knowing these characteristics you will want to place the cameras so a would-be intruder is most likely to cross the detection area rather than approach directly at or away from the camera.