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motion detector

Motion detectors are sensors that detect the movement of people and objects above a certain size and at a certain distance and generate an electrical signal.

Motion detectors are divided into those that work passively and those that work actively. Passive motion detectors include infrared sensors such as the passive infrared motion detector( PIR), which can detect the thermal radiation of people and animals. They do not emit their own signal and detect the infrared radiation.

It is different with the active motion detectors. They emit their own signal with which the detection area is radiated. It can be a continuously transmitted signal or an ultrasonic or RF burst transmitted at intervals. In the first case, the receiving device detects the received signal and compares it with the usual signal image. In the second case, the Doppler effect is used and changes in propagation timeare detected. Active motion detectors include the ultrasonic motion detector as well as RF motion detectors and radar motion detectors.

Passive infrared motion detector from Steinel, photo:

Passive infrared motion detector from Steinel, photo:

Motion detectors are used in security systems and alarm systems to protect buildings and rooms. If motion is detected, then the generated signal triggers an alarm.

Another application of motion detectors is in lighting technology. In this application, the signal is used to activate the lighting. This technology is used in room and house lighting. Furthermore, motion detectors are used in building technology for opening doors or in traffic technology for traffic counting, switching traffic lights or other traffic signals.

Englisch: motion detector
Updated at: 21.04.2016
#Words: 253
Links: signal, infrared (IR), passive infrared (PIR), detector, passive infrared (PIR)
Translations: DE

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