What Is a Motion Sensor?

A motion sensor is a security sensor designed to recognize movement that occurs in the detection area. Motion detecting sensors are very frequently used with security systems in all environments. When a motion sensor detects movement, it will send a notification to the alarm panel.

An important job of a security system is to provide alerts when someone enters the property. One way that alarm systems do this is with motion detecting sensors. The devices respond to the movement of people and large objects within their detection range. In order for a motion sensor to work properly, it must be carefully mounted. Installing a motion sensor in a poor location can lead to false alarms. Motion sensors should not be facing any vents, ducts, moving ceiling fans, moving curtains, stairwells or windows that will allow heavy sunlight to enter the building.

The typical motion sensor uses passive infrared (PIR) technology to detect movement. The motion detector will look for changes in infrared (IR) energy that occur when a new person or object comes into the device's detection area. Every person and object emits a tiny amount of IR energy that is sensed by motion detectors. When a large enough change in IR energy occurs, then the motion sensor will alert the security system. Some motion sensors will allow you to adjust how large of a change in IR energy is needed to activate the device. This is done by increasing or decreasing the pulse count. Increasing the pulse count will require the sensor to detect a larger change in IR energy to activate. This will make the sensor less sensitive and less likely to cause false alarms. Likewise, decreasing the pulse count will have the opposite effect. A lower pulse count is only recommended for highly secure areas where there should be absolutely no movement that might cause false alarms. Most end users are fine with a lower device sensitive to avoid false alarms. Also be aware that some motion sensors may use microwave technology in addition to PIR detection. These are known as dual-tech motion detectors, and they can also be helpful for preventing false alarms.

End users have many options when it comes to choosing a motion sensor. A user will need to decide whether they want a PIR sensor or a dual-tech motion sensor. They will need to choose between an outdoor motion sensor and an indoor-only motion sensor. There is also the decision of hardwired or wireless. Most users will find that wireless motions are easier to install. Users who plan to use wireless motions must make sure that the devices communicate at a wireless frequency that is compatible with their systems. They should also consider the fact that they will need to replace the batteries for the device every few years. On the other hand, hardwired motion sensors are more difficult to install since wires must be run. Hardwired motion sensors are normally only used with hardwired systems. The upside is that wired motions don't require battery replacements.

Users with pets should strongly consider getting pet-immune motion sensors. These devices work by not detecting movement in the areas close to the ground where pets walk. However, they will still detector movement for humans walking upright. Please note that it is still very possible for small animals to activate pet-immune motion sensors. These devices are not perfect. If your pet climbs on top of something and gets in the sensor's field of view (FOV), then they can definitely activate it. You must make sure that your motion sensor is not facing any furniture or stairwells that your pet could use to get in the FOV. Also be aware that pets that jump around or move very quickly can still activate a motion sensors. End users should test their motion sensors with their pets to find out if this may be a problem. Most pet-immune motion sensors have a weight limit for pet immunity.