What is a Motion Detector Alarm?

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  • Written By: Jacob Queen
  • Edited By: Lauren Fritsky
  • Last Modified Date: 24 February 2018
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A motion detector alarm is a system designed to sound a warning when a person moves into a certain area of detection. Different motion detector alarm systems are made using different technologies, and they may do different things when someone breaks the zone of protection. Some of them turn on lights for example, while others may even automatically contact authorities. These are mainly for security, but they also have other potential uses.

Many motion detector alarm systems have different sensitivity settings to avoid false positives. If the sensitivity is set too high, it is possible for a motion detector alarm to go off from a dog walking past it or even a smaller animal like a squirrel. In cases like these, people will have constant problems with the alarms sounding unnecessarily, and they can become annoying. Depending on the technology used to create the motion detector alarm, the method of changing sensitivity can vary.


Some motion detector alarm systems are created using laser technology. A laser is generally set up on a poll or attached to something on someone’s lawn, like a tree. The laser will be pointing to a sensor that is set up some distance away. If the laser light going to the sensor is ever interrupted, the device will sound an alarm. To set up the sensitivity on these, an individual can set the laser up high enough so that only a person would be likely to break it. Homeowners can also often change the length of time the laser has to be broken before alarming.

Another kind of motion detector is designed using infrared technology. These work by detecting heat given off by living things. Setting up the sensitivity on an infrared system involves adjusting the size of the heat signature they will tolerate. These are generally set up so that only a person or something larger like a bear or a car could cause a problem.

Beyond the obvious security benefits of a motion detector alarm, they can also provide a certain level of convenience. If you set them up in the right place, they can alarm anytime a car enters a person’s driveway. This could be used to alert someone that guests have arrived. They can also be set up to turn on lights in a person’s house so that someone arriving home from work in the evening can walk into a lit house without having to do anything.



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