How Do Burglar Alarms Work
A burglar alarm is fairly simple in concept, but can actually be somewhat complex in its execution. In the simplest sense, a burglar alarm can be passive or active. An active burglar alarm transmits some kind of signal; when that signal is interrupted, the alarm will activate. A passive burglar alarm does not transmit a signal. Instead, it activates when it detects some kind of change. There are advantages to each kind of alarm. Which one is right for you will depend on what you are trying to protect.
Glass Break Detection
Glass break detectors are usually made of a passive alarm device and something with which to make the sound. The glass break detectors typically pick up the frequencies associated with glass breaking. So if someone breaks glass attached to a glass break detector, it’s actually the sound of the glass breaking that will trigger the alarm. They have a very low false alarm rate since so few frequencies sound anything like glass breaking. However, they can be fooled if a burglar has a glass cutters so you have to keep that factor in mind. There are other kinds of Birchanger burglar alarms.
An infrared detector is one that picks up changes in heat. Human body temperature tends to be in a very narrow range. Therefore, an infrared alarm will pick up increases in ambient temperature and/or the specific range of human body temperatures. They have a very low false alarm rate due to the narrowness of the range of body temperatures. They have higher false alarm rates if they are installed outside. The false alarms from one installed outside usually come from automobiles or animals.
These are two of the most common kinds of burglar alarms. There are many other types of alarms that could be right for you and your home.