PIR Motion Sensors

The PIR motion sensors or the Passive Infrared motion detectors make use of passive infrared technology which is the most advanced form of technology used in security and wireless video surveillance systems. These types of sensors usually need to be mounted on a wall or placed in the corner of a room.  The motion sensors work by emitting several layers of finger like invisible rays in a covered area.

The top layer among these rays has the capacity to travel the furthest and can cover as much as 60 feet in height as well as 35 feet on each side. In addition the middle and the bottom layers of the beams projected by the passive infrared motion wired detectors assist in sweeping the area closest to the sensor of the alarms. The beams produced by these motion sensors detect an intrusion or the presence of a foreign body by comparing the temperature difference of the individual beams with a surface or a foreign body that it strikes. So for instance if the beam from the PIR motion sensors strikes your couch, the motion sensor can identify its temperature.

So when you or anyone else walks by your couch while the sensor is activated, it will also be able to identify this new temperature. The PIR motion sensor will then compare both the temperatures and be able to tell you that there has been a violation. In addition the microchip present inside the passive motion detecting sensors can adjust to the slow changing temperature patterns in your room. Some of these motion detectors are designed in such a manner that they can provide a 360 viewing field downward. Thus it is very difficult to compromise the motion detectors of the Passive Infrared motion detectors.

But on the other hand, the PIR motion sensors have certain limitations or flaws. The motion sensors cannot see through the doors, windows or the walls in the rooms. Apart from that the beams or rays emitted by these motion sensors cannot bend around the corners. So if you have placed the Passive Infrared motion detector in an area that has an open door, the device will not be able to cover or provide protection when the door is shut. Another flaw is that you cannot use a single PIR motion sensor to provide protection for every square inch of space in your room. Instead you need to strategically place these sensors in areas that are more prone to intrusion or are more likely to be invaded by burglars and other unwanted intruders.

See the explanation about outdoor detector in our other articles.