Motion detector
From Wikipedia, the free encyclopedia
A motion detector is a device connected to a burglar alarm that is used to detect motion. If it detects motion and the burglar alarm is set, it sets off the alarm.
An electronic motion detector is a device that transforms the detection of motion into an electric signal.
An occupancy sensor is a device that senses when motion has stopped for a specified time period in order to trigger a light extinguishing signal. These devices prevent illumination of unoccupied spaces.
[edit] Types
There are basically three types of motion detectors still in use today. The most common and reliable motion detector uses infrared technology. Technology used:
- Passive infrared sensors (PIR)
- Detects changes in the infrared spectrum. Looks for body heat.
- Ultrasonic
- Sends out an emitting ultrasonic pulses and measures the reflection of a moving object.
- Microwave
- Microwaves are bounced off an object. Similar to a police radar gun.
[edit] Dual-technology motion detectors
Many modern motion detectors use a combination of different technologies. These dual-technology detectors benefit with each type of sensor, and false alarms are reduced. All companies have the option to use PIR/Microwave Motion Detectors that have "Pet-Immune" functions which allow the detector to ignore pets that weigh up to 40 pounds (wireless models) or 80 pounds (hard-wired models).