Motion sensor is decide used for detect moving objects. Specially, it is used for metabolics. Normally, motion sensors are passive type Infrarred motion detectors. They activate only when the moving objects detected by the sensor. All the metabolic releases Infra-red rays. So that,In all security applications passive motion sensors are mostly used.
Theother one type is an active motion sensors. They radiates the ultrasonic waves, when it’s distruped by the object in the reflecting path ultrasonic sensor activates the signal.
Here we see functionality of PIR motion sensor module.
The sensor is made with pyroelectric material which is a small rectangular crystal that placed inside the round metal. The purpose of using motion sensor is to detect the changes. so, we need to eliminate the average sensor of the measuring Environment.