A security alarm system can be used to detect intrusion – unauthorized entry – into a building or area. Security alarms are used in residential, commercial, industrial, and military properties for protection against burglary (theft) or property damage, as well as personal protection against intruders. car alarms likewise protect vehicles and their contents. Prisons also use security systems to control their inmates.
Some alarm systems serve a single purpose of burglary protection and 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. Systems range from small, self-contained noisemakers, to complicated, multi-area systems with computer monitoring and control.
Video door entry consists of both outside and indoor elements: a outdoor panel on the outside, an electronic lock release and an indoor monitor.
The most basic alarm consists of one or more sensors to detect intruders, and an alerting device to indicate the intrusion. However, a typical premises security alarm employs the following components:
- Premises control unit (PCU), Alarm Control Panel (ACP), or simply panel (Brain of the system)
- Sensors(sound, vibration, or other disturbances)
- Alerting Devices(bells, sirens, flashing lights)
- Keypads( small multi-character display)
- Interconnections(direct wiring, wireless links)
- Security Devices(spotlights, cameras & lasers)
In addition to the system itself, security alarms are often coupled with a monitoring service. In the event of an alarm, the premises control unit contacts a central monitoring station. Operators at the station see the signal and take appropriate action, such as contacting property owners, notifying police, or dispatching private security forces. Such signals may be transmitted via dedicated alarm circuits, telephone lines, or Internet.
Some of the types of sensors used are:
- Passive infrared detectors.
- Ultrasonic detectors.
- Microwave detectors.
- Compact Surveillance Radar.
- Photo-electric beams.
- Glass break detection.
- Smoke, heat, and carbon monoxide detectors.
- Motion Sensors.
- Driveway Alarms.
- Vibration (shaker) or inertia sensors.
- Fiber optic cable.
- Security electric fence.