Burglar (or intrusion), alarms are systems designed to detect unauthorized entry into a building or area. They consist of an array of sensors, a control panel and alerting system, and interconnections. Sensors detect intruders by many methods such as monitoring door and window contacts, by passive infrared motion detectors, ultrasound, vibration, electric or magnetic fields, or microwaves. Sensors may be directly wired to a control panel that provides sensor power, or may communicate wirelessly. Some alarm systems serve a single purpose of burglar or fire protection. Combination systems provide both fire and intrusion protection. Intrusion alarm systems may also be combined with closed-circuit television surveillance systems to automatically record the activities of intruders, and may interface to access control systems for electrically locked doors.
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