Electronic motion detector
An
Electronic motion detector contains a motion sensor that transforms the detection of motion into an electric signal. This can be achieved by measuring optical or acoustical changes in the field of view. Most motion detectors can detect up to50-80 feet.
A motion detector may be connected to a burglar alarm that is used to alert the home owner or security service after it detects motion. Such a detector may also trigger a red light camera.
An occupancy sensor is a motion detector that is integrated with a timing device. It 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 like public toilets.
There are basically three types of sensors used in motion detectors spectrum:
1-Passive infrared sensors (PIR)Looks for body heat. No energy is emitted from the sensor.
2-Ultrasonic (active)Sensor sends out pulses and measures the reflection off a moving object.
3-Microwave (active)Sensor sends out microwave pulses and measures the reflection off a moving object. Similar to a police radar gun.
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 80 pounds. Placement of the sensors can be strategically mounted so as to lessen the chance of pets errantly activating alarms.
Often, PIR technology will be paired with another model to maximize accuracy and reduce energy usage. PIR draws less energy than microwave detection, and so many sensors are calibrated so that when the PIR sensor is tripped, it activates a microwave sensor. If the latter also picks up an intruder, then the alarm is sounded. As interior motion detectors do not ‘see’ through windows or walls, motion-sensitive outdoor lighting is often recommended to enhance comprehensive efforts to protect your property.
False alarms are those usually caused by technical errors such as electrical and mechanical failures. Nuisance alarms are system activations not commonly caused by attackers or inturders but rather from wind blown debris, animals, insects and foliage.
Sequencing alarm systems to trip the alert mechanism only when both alarm sensors have been activated will reduce nuisance alarms, but may also cause the probability of detection to decrease.
