Mission Possible: Protect valuable spaces with a well-designed burglar alarm

3 minute read

Hollywood movies like Mission Impossible leave us to believe that burglars always find a way. Build a fence and someone will climb it. Install a high-tech vault and someone will bypass the combination. Have an alarm system triggered by a complex array of lasers, sensors and biometric readers? The master thief rappels through a forgotten air duct.

In reality, well-planned burglar alarm systems can discourage thieves and quickly warn security teams about attempted break-ins.

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Every system includes some form of sensor, control unit and reporting device. Once a sensor detects an intruder, it feeds data to a control unit. The control unit then communicates with a reporting device such as a siren or bell, or reaches out to a receiving unit in a remote location.

But sensors can detect intruders many different ways.

Area protection devices, for example, use photoelectric, sound or motion detectors to spot an intruder’s movements. Perimeter protection devices — as their name implies — watch over a perimeter defined by a fence or a building’s walls. Ultrasonic motion detectors monitor sound frequencies, while passive infrared designs watch for the infrared energy that radiates off an intruder’s body. Movements can also be tracked using microwave motion detectors.

Those people who are looking to secure a safe or metal vault, meanwhile, might opt for a capacitance detection system, which sounds an alarm if someone touches the metal surface. And particularly valuable items might deserve an object protection device, which can monitor the surrounding space using pressure mats, contact switches, or detectors that track vibrations, sound, smoke or heat.

The systems which rely on at least two different technologies are the least likely to trigger false alarms.

Of course, some of the weakest points in any perimeter will include doors, windows or other natural openings. These threats can be monitored by mechanical contact switches, mercury switches, or magnetic contacts. Metallic foil sensors will watch over glazed surfaces such as windows. And even if a burglar manages to step through such openings, they might trigger the electromechanical switch in a pressure mat, or pass across the wired electrical barrier of a burglar “screen”. Alarms can also be triggered when someone crosses a photoelectric detector’s beam of invisible light, creates a disturbance in an area with a vibration system, or makes a noise picked up by the microphones in a sound-based system.

Virtually any disturbance can be tracked.

Overall, the level of protection will vary depending on just how much is being watched. Underwriters Laboratories of Canada rates the systems in four categories. A Level 1 system monitors all accessible openings, while its Level 2 counterpart also watches inaccessible but moveable openings. Level 3 introduces another layer of protection by watching shared walls, floors and ceilings. The Level 4 systems will watch every opening, wall, floor or ceiling.

Regardless of the category, the most effective systems communicate with remote monitoring stations, transferring their data using options such as phone lines, radio signals, the internet, direct wires and transmitters, cell signals or data networks. Line supervision features will ensure that such signals are transmitted even if a burglar cuts a telephone line or tries to interfere with a radio signal, while lines can be further protected using standard or encrypted security methods.

It proves that even a security system deserves some added security.