A motion detector is an electronic device that detects the physical movement in a given area and transforms motion into an electric signal. The motion detector may be electrically connected to devices such as security, lighting, audio alarms, and the like. Motion sensors are used in a wide variety of applications and as a result many different types of motion sensors are available. Motion detectors are mainly used in for security systems. For example, motion detectors are typically positioned near exterior doorways or windows of a building for monitoring the area around the building. Upon detecting motion, they generate an electrical signal that is transmitted to a preselected audible alarm or lighting device which is then activated. A number of different technologies are used for motion detection. Motion detectors typically employ ultrasound, passive infrared (PIR), or radar detection techniques. Among the most used and most effective type of intrusion detection devices are the passive IR detectors which in recent years have replaced other types such as microwave or ultrasonic detectors.
TYPES OF SENSORS
Microwave sensors are used in large apartments since microwaves can penetrate through dielectric mediums. But they are generally not used because the unit consists of expensive super-high frequecy component whose radiations are not healthy for living organism Infrared sensors
Infrared (IR) detectors are widely known in the arts of intrusion detection and in fire/smoke detection. These detectors have basically two forms: active and passive.
Active IR detectors include a radiation source and an IR sensor which is sensitive to interruptions in the radiation sensed from the source. These detectors are used as intrusion detectors by providing a path of radiation from the source to the sensor in a place where the path is likely to be interrupted by an intruder.
A passive infrared motion detection system...
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