Motion Sensors

Motion Sensors detect movement by measuring optical changes or acoustical changes in its field of view.  Most detectors has a detection range up to 15 meters.  There are three types of motion sensors:

• Passive Infra Red Sensors (PIR) which detect movement by looking for body heat

• Ultrasonic Sensors that sends out pulses and measures reflection off a moving object

• Microwave Sensors that send out microwave pulses and measures reflection off a moving object 

To reduce false alarm, some sensors may use a combination of different technologies.  Most dual-technology detectors incorporate the PIR technology with Ultrasonic or Microwave technology.  They are designed such that Ultrasonic or Microwave pulses are sent only when the PIR sensor is tripped.

The key to reducing false alarm lies on the selection of detectors and their strategic, correct placement.  For example, PIR Motion Sensors should not face open windows as it may pick up heat changes caused by the headlights of a passing car.  And for homes with pets, Pet Immunity Motion Sensors should be use to reduce false alarm caused by pets running about the premises.