Many years ago, I managed a semi-rural gas station and convenience store. The building was pretty old and would have benefited tremendously from a few upgrades. It was equipped with a security system that caused me plenty of frustration due to frequent false alarms. One particular wave of false alarms was traced back to a motion sensor near the rear of the building.
That building and its security system were brought to the forefront of my mind by a post on the Vivint Home Security website. The post in question discussed a variety of things that can trigger false alarms with motion sensors. As I read it, many memories of the past came flooding back.
Motion sensors are handy devices suitable for any home or business security system. As far as electronic security is concerned, any device that can alert you to a potential problem is a good device. It’s just that some devices are fussier than others. Motion sensors tend to be near the top of the list in terms of fussiness.
The Basic Motion Sensor
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A motion sensor is a device that picks up motion through one of a variety of different means. The most basic of all motion sensors rely on infrared radiation, a type of radiation that is emitted by warm objects or creatures. When all is at rest, the sensor observes a consistent radiation pattern. But that pattern is interrupted when movement occurs, thus triggering the sensor.
There are other types of sensors:
- Microwave – A microwave sensor combines microwave signals with the Doppler effect to measure changes in frequency shifts. Movement creates such a shift.
- Ultrasonic – An ultrasonic sensor emits sound waves that are all reflected back. When movement is detected, the sound waves are not reflected back in the same way. This triggers the alarm.
- Dual-Technology – A dual-technology motion sensor combines both microwave and ultrasonic components. It provides maximum coverage.
- Tomographic – Tomographic sensors rely on a mesh network of nodes to measure radio waves. Movement disrupts radio waves and triggers the sensor.
Although technologies differ slightly, they all rely on the same basic principle: detecting movement by measuring some sort of energy. As long as energy remains consistent, all is well. But the first sign of inconsistency is interpreted as motion.
Lots of False Alarm Triggers
With a basic understanding of how motion sensors work, it should be apparent that there are a lot of things that can trigger false alarms. A false alarm can be annoying when it is triggered in the middle of the night. It can be equally annoying during the middle of the day, especially when you are at work and trying to concentrate on something important.
Here are just some of the things that can trigger false alarms:
1. Animals
According to Vivint, animals are the leading cause of home security false alarms across the country. They specifically mention indoor pets. It makes sense. Pets have a habit of moving around the house at various points throughout the day. Since motion sensors are designed to pick up all sorts of motion, they will pick up pet movement.
How does one avoid pets triggering false alarms? There are options:
- Avoid installing motion sensors where pets are known to spend a lot of time.
- Adjust sensitivity settings so that sensors are not as touchy.
- Install dual-technology motion sensors with a high level of accuracy.
Sometimes it is a matter of how motion sensors are positioned. For example, your only pet may be a small dog who doesn’t have a habit of climbing on things. Pointing motion sensors could solve your problem.
2. Environmental Factors
Certain types of environmental factors are capable of tripping motion sensors unintentionally. Quick temperature changes and direct sunlight are prime examples. Temperature and sunlight are especially problematic for infrared sensors.
Let’s say you have an infrared sensor installed on the wall of the family room. Opposite the sensor is a picture window facing south. Just about midmorning, once the sun makes it up over the top of the tree line, you could get a burst of direct sunlight through that window. It could be enough to disrupt the heat pattern and trigger your motion sensor.
3. Inanimate Objects
Believe it or not, inanimate objects can also trigger false alarms. To illustrate the point, let’s go back to my past experience at the gas station. Earlier, I mentioned that a particular wave of false alarms was traced back to a faulty motion sensor in the back of the building.
That motion sensor was fairly close to the back door. In and of itself, the location was not a problem. But it became a problem whenever the wind started blowing.
The rear door of the building was a steel security door with a dual bolt locking mechanism. Because of the way it was designed, the door did not close and lock tightly in place. It was engineered with a slight bit of flexibility to ensure the locking mechanism worked. So whenever the wind started blowing, the door would rattle a bit.
We had no problems when the motion sensor was new. But as it aged, it started giving me problems. It eventually began triggering an alarm every time the wind blew. Once we figured it out, stopping the false alarms was a simple matter of replacing the motion sensor and finding a way to keep the door from rattling.
Not Foolproof Devices
Motion sensors represent great technology for keeping homes and businesses safer. But they aren’t foolproof. They can be inadvertently triggered, leading to false alarms that are both annoying and potentially costly – especially when local police departments assess fines for false alarms.
If you have motion sensors that are triggering false alarms, start looking around for potential causes. Maybe it’s your pets. Perhaps you’re looking at environmental factors. Or maybe you just have a faulty sensor being triggered by a rattling door or window. The sooner you find the problem the sooner you stop the false alarms.