What is PIR?

What is PIR?

PIR stands for Passive Infra Red. A passive infrared sensor is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. PIR sensors are most often used in PIR-based motion detectors.

A PIR-based motion detector is used to sense movement of people, animals, or other objects. They are commonly used in burglar alarms and in automatically-activated lighting systems. They are commonly called simply “PIR”, or sometimes “PID”, for “passive infrared detector”.

Mobeye pir alarms

How do PIR sensors work?

A passive infra red sensor detects the infrared light radiated by a warm object.

All objects with a temperature above absolute zero emit heat energy in the form of radiation. Usually this radiation isn’t visible to the human eye because it radiates at infrared wavelengths, but it can be detected by electronic devices designed for such a purpose.

PIR motion sensor

Mobeye Argos pir motion alarm

A PIR sensor detects moving heat sources. The (Fresnel) lens consists of several parts; once the thermal image (infrared radiation) changes, the detector responds. People and large animals are noticed; small animals like insects and spiders are not.

The term passive in this instance refers to the fact that Passive Infra Red devices do not generate or radiate energy for detection purposes. They work entirely by detecting infrared radiation emitted by or reflected from objects. They do not detect or measure “heat”.

How to reduce false alarms

Mobeye Outdoor detection

As previously stated, any “moving heat source” may set off an alarm. This means that draughts, windy areas, and direct sunlight are all heat sources to avoid. Incorrect reports are also produced by glare as a reflection on black leather. If a false alarm occurs, the alarm system’s position or sensor sensitivity must be adjusted.

Many Mobeye products include a passive infra red sensor or can be used combined with a passive infra red sensor as accessory. Because it has a dual detector for verification, the Mobeye Outdoor Alarm detector, for example, filters out the majority of these sources. This works particularly well in windy conditions. The CMVXI-R is built on Optex’s market-leading external PIR, which is the world leader in PIR technology.

The unit has two detection patterns, both of which must be broken simultaneously in order to trigger the alarm. This results in the detector being highly immune to false alarms created by birds, cats, dogs etc. as these animals will not trigger both the top and bottom detectors at the same time.

Digital Double Layer Detection

The two internal PIR sensors independently analyze the detection so that a misleading coincidence of events can be filtered out. This technology virtually eliminates detections of smaller animals in the premises. The VXI-R model is equipped with a digitally enhanced signal recognition logic called SMDA. SMDA improves immunity against various noise factors such as climate changes and vegetation sways.

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