Motion detectors can be an extra line of defence for any security system. Burglars have many ways to overcome trip lines and other elements of alarm systems, but overcoming motion detectors does add an extra level of difficulty. If you want a really robust alarm system, make sure that you go for one with motion detectors.

Motion detectors tend to work through line-interruption, just like most sensors. This means that they create a line, which is then monitored, and when the line is broken the alarm is triggered. Motion detectors tend to fit in this category as they create a line of infra-red light which is reflected back to the sensor. If this line of light is interrupted then the reflection won’t reach the sensor, and the alarm is triggered. There are alternative forms of motion detectors, but this is the primary and most readily available form of motion detection. You can also get ones which monitor the acoustic and microwave fields instead, although these tend to be rarely, and can be less effective in home security.