How Do Motion Detectors Work? (Intruder Alarms)

Intruder alarms using motion detecting technology are one of the most popular means of protecting both domestic and commercial properties. Partly that’s because they can be relatively affordable and easy to install, and partly it’s because they do that most basic of things when they detect something – they make a lot of noise that is designed to make the intruder give up and run.

These systems come in a variety of types, all of which are designed in one way or another to detect the presence of unwanted and illicit intruders. For businesses, the alarms in question will usually be activated outside of business hours when there shouldn’t be anyone on the premises in question.

This article will examine how these sensors work and, more importantly, whether they can actually protect your business.

How do motion detectors work?

There are several types of motion detectors of varying reliability, these being perhaps the most common and most effective:

• Passive Infrared (PIR)

Probably the most common type of motion detector, these emit infrared waves that can detect changes in temperature caused by the presence and movement of people. Versions of this type of system when used in domestic properties can be set up such that they will only pick up on something large enough to be a person, so that cats wandering past the sensors don’t set off the alarm.

• Active Ultrasonic

These sensors emit ultrasonic (i.e. high frequency) sound waves, with an alarm being triggered when something interferes with them. 

• Contact sensors

These sensors are less about detecting the movement of people, and more about detecting the movement of things, specifically doors and windows. Intruders have to get in somehow, so by picking up on them the minute they force open a means of entry, the quicker an alarm will be raised.

Can motion detectors reduce crime?

There’s a reason these kinds of sensors are so popular and that is because they can act as an effective deterrent. That’s why houses and businesses that have them installed (and also many that don’t) have a box attached to the front of the building advertising the fact. 

On their own, they are most effective against opportunistic thieves, who are more likely to be put off if they think such a system is installed or give up if they set off an alarm.

However, they are at their most effective when paired with a 24/7 monitoring system. It has been shown that police rarely attend when an intruder alarm is reported by a member of the public, but when an incident is reported by an Alarm Receiving Centre (ARC), the police do respond and investigate quickly. 

Are motion detector systems easy to install?

At Scutum London, we supply and install both wireless and hardwired intruder alarm systems. Each has its own advantages but, with no wires to fit in, the wireless systems are definitely the easier and least disruptive to install. 

How do I get a motion detector system?

Here at Scutum London, we design, supply, install and maintain intruder alarm systems using motion detection and other tools to keep your premises safe. We also run an Alarm Receiving Centre, which means someone on our team will always be on hand to immediately alert the authorities should your intruder alarm be triggered.

To find out more, or to arrange for a free site visit and cost-effective quotation, get in touch with the team at Scutum London now.