This allows the device to resist false indications of change in the event of being exposed to brief flashes of light or field-wide illumination. In such a configuration, the PIR measurements cancel each other so that the average temperature of the field of view is removed from the electrical signal an increase of IR energy across the entire sensor is self-cancelling and will not trigger the device. There are also PIRs designed with reversible orientation mirrors which allow either broad coverage (110° wide) or very narrow 'curtain' coverage, or with individually selectable segments to 'shape' the coverage.Differential detection Pairs of sensor elements may be wired as opposite inputs to a. Some larger PIRs are made with single segment mirrors and can sense changes in infrared energy over 30 meters (100 feet) from the PIR. Models with wider fields of view, including 360°, are available, typically designed to mount on a ceiling.

The most common models have numerous or mirror segments, an effective range of about 10 meters (30 feet), and a field of view less than 180°. Objects of similar temperature but different surface characteristics may also have a different infrared emission pattern, and thus moving them with respect to the background may trigger the detector as well.PIRs come in many configurations for a wide variety of applications. The sensor converts the resulting change in the incoming infrared radiation into a change in the output voltage, and this triggers the detection. When an object, such as a person, passes in front of the background, such as a wall, the temperature at that point in the sensor's field of view will rise from to, and then back again. They are commonly used in and automatically-activated systems.Operation A PIR sensor can detect changes in the amount of infrared radiation impinging upon it, which varies depending on the temperature and surface characteristics of the objects in front of the sensor.

An indoor light switch equipped with PIR-basedA PIR-based is used to sense movement of people, animals, or other objects.

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