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A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors . PIR sensors are commonly used in security alarms and automatic lighting applications.
Remote alarm systems are used to connect the control unit to a predetermined monitor of some sort, and they are available in many different configurations. Advanced systems connect to a central station or first responder (e.g. police/fire/medical) via a direct phone wire, a cellular network, a radio network, or an IP path.
Most of these were connected to the set being controlled by wires, but the Philco Mystery Control (1939) was a battery-operated low-frequency radio transmitter, [14] thus making it the first wireless remote control for a consumer electronics device. Using pulse-count modulation, this also was the first digital wireless remote control.
A passive infrared detector mounted on circuit board (right), along with photoresistive detector for visible light (left). This is the type most commonly encountered in household motion sensing devices and is designed to turn on a light only when motion is detected and when the surrounding environment is sufficiently dark.
The key contains a power supply device, usually a rechargeable battery or a replaceable battery in the key, used to drive the system to work; it also includes an electronic storage and control device for storing the identification code of the lock. The software is used to set and modify the data of each key and lock. [2]
Remote photoelectric sensors used for remote sensing contain only the optical components of a sensor. The circuitry for power input, amplification, and output switching is located elsewhere, typically in a control panel. This allows the sensor, itself, to be very small. Also, the controls for the sensor are more accessible, since they may be ...
An infrared detector is a detector that reacts to infrared (IR) radiation. The two main types of detectors are thermal and photonic (photodetectors). The thermal effects of the incident IR radiation can be followed through many temperature dependent phenomena. [2] Bolometers and microbolometers are based on changes in resistance.
Occupancy sensor types include: PIR sensors, which work on heat difference detection, measuring infrared radiation.Inside the device is a pyroelectric sensor which can detect the sudden presence of objects (such as humans) who radiate a temperature different from the temperature of the background, such as the room temperature of a wall.