Burglar (or intrusion), fire, and safety alarms are all electronic today. Sensors are connected to a control unit via a low-voltage hardwire or narrowband RF signal which is used to interact with a response device. The most common security sensors indicate the opening of a door or window or detect motion via passive infrared (PIR). New construction systems are predominately hardwired for economy. Retrofit installations often use wireless systems for a more economical and quicker install. Some systems serve a single purpose of burglary or fire protection. Combination systems provide both fire and intrusion protection. Sophistication ranges from small, self-contained noisemakers, to complicated, multi-zoned systems with color-coded computer monitor outputs. Many of these concepts also apply to portable alarms for protecting cars, trucks or other vehicles and their contents (i.e., “car alarms”). Burglar alarms are sometimes referred to as alarm systems.
Burglar alarms (or perimeter detection systems, Perimeter protection, intrusion detection systems and many more terms for the same thing) are divided to two main fields: home burglar alarms and industrial burglar and perimeter intrusion detection.