PIR is the acronym for Passive Infra-Red. Which is a highly effective, low cost technology for detecting activity in the area you are watching by monitoring changes in infra-red heat patterns.
When an intruder enters a room the PIR will pick up the change in temperature and trigger an alarm or security recording. Passive infrared (PIR) detection system are like a memory bank that remember how much infrared energy typically gets focused on its surface when there is no activity in the area.
Passive infra-red’s are an excellent choice for security systems because of their low power use. Low power use means battery powered alarms and hidden cameras can run longer on a single battery. PIR systems use less power because they are “passive”. A surveillance camera with PIR motion detection is only sensing the infrared energy coming in to their sensors from the area being monitored. Passive systems do not beam out their own own infra-red lighting which uses more power and decreases battery life.
How PIR is used in a motion detector hidden camera.
The electronics of a PIR motion detection camera sit in a passive state and are connected to the input of a burglar alarm or motion detector hidden camera. If an intruder enters, he gives off infrared energy (heat) which cannot be seen by the human eye, but can be picked up by electronic sensors. The PIR sensor picks up the radiation change emitted by a burglar, compares the old state of infrared energy to the new state, calculates the change and then triggers the alarm or video recording.
Placement of PIR Motion Detection Cameras & Alarms
Alwasys install your PIR camera or alarm in an unobstructed position with a clear view of the entire security area you want monitored. Good choices include a ceiling or a large open wall. This is why manufacturers offer smoke detector hidden cameras or cameras built into emergency lights.
Placement of passive detection systems is very important. A PIR should not be placed near an HVAC vent that could blow hot or cold air onto the unit. While air does not emit much infrared energy, the air coming from a vent could change the temperature enough to confuse the electronic system.
Range of Motion Detection
Passive infrared (PIR) detection systems use a number of lenses or mirrors to give them an average range of about 25-30 feet. More expensive PIR’s feature single segment mirrors and can cover more than 100 feet. Some high end units detect changes up to 400 feet.
You can protect a particular area like the floor space surrounding a safe by purchasing a PIR with a very narrow coverage. Conversely, PIRs can also be designed for a broader angle of coverage.
Avoiding Motion Detection False Alarms
Typically a PIR sensor is placed on a circuit board that has the equipment to interpret signals from the sensor and then covered with a protective housing. This housing keeps out dust and insects which could obstruct the sensor. The plastic housing is also useful because the infrared energy of insects could generate false alarms.
If you are using an alarm with auto dialing false alarms cost local police money. Plus, if your neighbors get used to false alarms they may begin to ignore the alarm signals and become unlikely to act in the event of a real burglary alarm.
When infrared energy from a potential intruder reaches the passive infrared (PIR) detection device sensor array window, the infrared energy passes through the plastic housing covering the circuit board.
Is PIR Motion Detection Expensive?
You can get PIR motion detection equipment fairly inexpensively but you should consider is the lower cost units have all the features you require. Basic devices start at approximately $15 whereas a long-range detector sells for over $1,200.
