A passive infrared motion detector is a security system that works mainly on detecting body heat of human beings and animal whose radiation is strongest at a wavelength of 9.4 um. This is ideally used in houses that are left in an extended period. Say family is going out for a long vacation. It is an electronic gadget that measures infrared light energy radiating from objects within its field of view known as blackbody radiation. This can be detected by various designed electronic devices however invisible to human eye. It is called a passive detector since it does not emit an infrared beam, thus accepts incoming infrared signals.
How does a passive infrared motion detector works? When a person enters a monitored area, the intruder’s body heat is focused by a mirror segment or known As the Fresnel lens – a Plano Convex flat lens that retains optical capability and overlaps the zone of the chip that was previously looking at some lower temperature protected areas such as walls. This system can detect a motion as far as 6 feet away. As the person moves, the hot spot surface of the chip moves along the motion causing the electronics on chip to de-energize the relay sending signals to the control panel resulting alarm activation.
The passive infrared motion detector is very small that makes it easy to conceal. The size of this is just about an inch that is barely noticeable. It is recommended to place this motion detector on entrance and exit doors. However, since it detects body heat, this does not exempt the presence of dogs unless you take the dogs with you when you are out for a vacation or vacate dogs in areas that can’t be reached by the infrared receptors. Do not forget to keep possessions safe when you are away.
