Detectors are important constituents of modern security systems because they provide necessary data to other devices for their proper functioning. A detector is a device that measures a physical quantity and transforms it into digital signals to be sent to other devices attached to it. Usually an alarm system requires some kind of detectors to sense the presence of a suspicious person or object within the area under its purview.
Security personnels use a special kind of detector to know if someone is carrying a metallic instrument for mass killing, such as a gun or a knife. Such detectors are known as metal detectors and are widely used in India and other parts of the world. They have become a common sight at places where security is of prime concern, such as airports, railways, government offices and some public places.
There are motion detectors to detect suspicious movement of strangers and people with bad intention within an area under surveillance. Most of these use infrared technology to produce reliable signals for an alerting device. Motion detectors with dual technology offer even more reliability as they get activated only where is a change in movement as well as temperature. An alarm system depends much on the effectiveness of detectors in sensing a movement made by a suspicious person or object. Smoke detectors and Fire detectors are other kinds of detectors commonly used India.
