What Is a Wireless Alarm System?

By Robert Vaux

  • Overview

    A wireless alarm system is one that uses self-contained components rather than components that run through a centralized set-up. Wired alarm systems are usually powered by the electrical grid in your home, connected to a central box that extends wires through the walls to the various sensors covering doors, windows, exterior detectors and motion sensors. With a wireless alarm system, all of those components have their own power supplies, rendering them easily portable and able to function independently of the household electrical grid.
  • Door and Window Sensors

    Door and window sensors usually consists of two pieces that interact in conjunction with one another. The first piece typically contains a magnet and is placed on the door or window. The second piece holds the alarm and a switch or trigger held in place by the magnet. It's placed on the door frame or the window frame so it is in contact with the magnet piece when the door or window is closed. When the door opens, the magnet moves, which turns the switch and activates the alarm.
  • Motion Detectors

    Wireless motion detectors act through a number of different methods, most commonly by either radar-style signals or by infrared detection. In the case of the former, the detector sends signals throughout the area it is designed to protect, which then bounce off stationary objects and return to the detector. When someone moves in the area, the signals bounce back more quickly. This alters the pattern of the signals, which alerts the detector and sets off the alarm. Infrared sensors, on the other hand, detect heat signatures in the area. When a warm-blooded creature of a specified size (a person, for example) passes into its range, the heat signature goes up and the detector spots the increase in IR energy.


  • Connected or Self-Contained

    A complete wireless alarm system will likely have multiple components, covering every entry way on the ground floor, motion sensors in key areas such as the back yard and sensors in the driveway or garage door which detect the arrival of a car. With self contained systems, each component has its own individual alarm, which will go off whenever the particular area it monitors is breached. More sophisticated systems have recently come to the marketplace, however, which allow for a fully integrated system. Each individual component sends a radio signal to a centralized box, which contains the activation software and the alarm itself. That allows you to activate and deactivate the entire alarm system at once, without resorting to the complexities of running wires to everything.
  • Benefits

    The benefits of a wireless alarm system are numerous. Because they are small and portable, they can be easily installed by any homeowner and moved to another house whenever the homeowner moves. The lack of wiring means they are much cheaper than other systems as well: a simple wireless door alarm costs about $10 and even the most sophisticated models top out at about $200 for a complete system. Finally, because they use an independent power source, they continue to function in the event of an electrical disturbance, and burglars cannot disable them by cutting power to the house.
  • Drawbacks

    The disadvantages of wireless alarm systems are related to their benefits. Simplicity and ease of use can limit their effectiveness in certain situations. Most importantly, many of them lack the ability to notify the police or other authorities: there is no monitoring service, only the alarm itself, which means the onus is on the homeowner to dial 911. Furthermore, an independent power supply means that the batteries need to be routinely checked and replaced regularly when they run low on power.
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