Different Types of Indoor Security Detectors

By: Art Gib

In the movies we often see break-in scenes where a burglar bypasses or is caught by a variety of different detection systems. Often these systems are fabricated or made-up to enhance the drama and action. But sometimes the technology we see in the movies is a real and available source of security. Here are just a few of the types of technology for indoor alarm devices that are actually available today. Though many of these may be typically used only in industrial alarm systems, some are used in more advanced home security alarm systems.

Passive Infrared Detectors

Because it is affordable and reliable, the Passive Infrared Detector (or PIR) is one of the most common types of detection used in homes and small businesses. The PIR monitors the ambient temperature of the desired space for change that might be caused by an infrared emitting object or person. It uses the principle of differentiation, which checks presence or non-presence to verify if a person is actually there.

Ultrasonic Detectors

Ultrasonic Detectors are active detectors that emit an ultrasonic wave that is inaudible to humans. The sound waves are transmitted by the receiver, reflected off hard-surface objects and then detected by the receiver. The device will detect a change in wave frequency that is caused by motion.

Photo-Electric Beams

This device transmits photo or infrared light beams across an area where the beam might be obstructed by a moving intruder. This device, because of the dramatic nature of its technology, is popular in films. One problem with this device is that it can sometimes be avoided if the intruder is aware of its presence, making it somewhat less reliable than other methods.

Glass Break Detectors

Glass generates sound in a wide band of frequencies when it breaks. Glass break detectors are mounted next to the glass panes and listen for the frequencies that are associated with breaking glass. Seismic glass break detectors are installed on the glass itself and detect the shock frequencies that travel through the glass, frame, and even walls.

These are just a few of the types of technology available today for security systems. Some advanced home security systems, such as the devices employed by ADT, may use these types of alarm devices or even more advanced types of detection devices. So, although in some cases the technology we see in the movies may be fabricated, much if it is as a result of real modern advances in security.