Home Security Systems

Written By: Laure Justice

Outdoor motion detectors are similar to indoor ones, but are more robust. They use various technologies such as infrared, ultrasonic, microwave, tomographic and combination devices and if triggered can set off an alarm or contact a security company.

Types of outdoor motion detectors

All motion detectors used outdoors are not ideal for security because there can be a lot of false positives caused by animals and callers while you are out. An exception to this is if you have a property with locked gates – in this case you could use motion detectors to secure the outside of the building, but you still may get false positives due to animals.

Motion detectors used outdoors often serve to automatically turn on lights instead of providing direct security. This is useful if you are coming home in the dark for finding keys or navigating along a dark path.

• Infrared outdoor motion sensors measure body-heat and other heat. They are not typically used because the weather can affect temperature quite easily causing false alarms. If they are used, then it is usually in a combination device that rules out false positives.


• Ultrasound motion detectors can be used outdoors by using sound waves to detect if there is a change in position of objects.


• Microwave devices use similar reflective technologies and work like a police radar gun.


• Tomographic detectors reflect radio waves.

How they can protect you and functions

Motion detectors placed outside can be hooked up to your security system and can work in tandem with other security features. For instance, if the motion detector is triggered then surveillance video can begin recording, or a doorbell can ring. If the area is supposed to be highly secure then they can also be set to trigger alarms and even call a security company to investigate the disturbance.

Differences between indoor and outdoor detectors

Outdoor motion detectors are best for areas which are supposed to be secure and free of intrusions. Another good place to use the devices is near a pool – these can be turned on when the pool is not supposed to be used so you have a warning if young children manage to get through the security gate around the pool.

They are usually more weatherproof (waterproof and dust-proof; look for models that are IP54 compliant) than indoor detectors and their usable temperature range is also much greater (-4ºF to 122ºF; -20ºC to 50ºC).

Because they are outside, they can also be placed in locations where people would not normally look and try to disarm them, such as under gutters, on roofs, in trees or even mounted on high poles.

Many outdoor motion detectors solve the problems posed by animals by being able to discriminate between the motion of an animal or a human. This is done in infrared and microwave devices by using two beams as opposed to one, that trigger if they are both crossed. Animals likely to be around a property are not usually bigger than cats or dogs so this effectively rules out false alarms caused by pets.

Outdoor devices also usually have more precise range settings, letting you tailor the detection to the range you need. They often also let you extend the range by using an automatic swivel that the detector is mounted on.

There are also outdoor infrared motion detection cameras that can be used to trap animals around your property. This can be useful if you have wild, dangerous animals such as bears. You can find more information about these devices on this professional trapping devices website.

Typical prices

The prices of outdoor security systems can vary wildly. If you are looking for a device that you can install yourself and that does not need to be hooked up to anything but a local alarm system, then you can expect to pay anything between $50-$200. However, if you're looking for a high tech solution that also comes with remote monitoring and the ability to call a security company, then it can set you back at well over $1000 not including the contract and monthly/annual maintenance.