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A security alarm[1] is a system designed 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. Prisonsalso use security systems for control of inmates.
Some alarm systems serve a single purpose of burglary 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. Systems range from small, self-contained noisemakers, to complicated, multi-area systems with computer monitoring and control.
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: The “brain” of the system, it reads sensor inputs, tracks arm/disarm status, and signals intrusions. In modern systems, this is typically one or more computer circuit boards inside a metal enclosure, along with a power supply.
- Sensors: Devices which detect intrusions. Sensors may be placed at the perimeter of the protected area, within it, or both. Sensors can detect intruders by a variety of methods, such as monitoring doors and windows for opening, or by monitoring unoccupied interiors for motions, sound, vibration, or other disturbances.
- Alerting devices: These indicate an alarm condition. Most commonly, these are bells, sirens, and/or flashing lights. Alerting devices serve the dual purposes of warning occupants of intrusion, and potentially scaring off burglars. These devices may also be used to warn occupants of a fire or smoke condition.
- Keypads: Small devices, typically wall-mounted, which function as the human-machine interface to the system. In addition to buttons, keypads typically feature indicator lights, a small multi-character display, or both.
- Interconnections between components. This may consist of direct wiring to the control unit, or wireless links with local power supplies.
- Security devices: Devices to detect thieves such as 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.
Niagara Falls
Niagara Falls (/naɪˈæɡrə/ ny-ag-ra) is a city in Niagara County, New York, United States. As of the 2010 census, the city had a total population of 50,193, down from the 55,593 recorded in the 2000 census. It is adjacent to the Niagara River, across from the city of Niagara Falls, Ontario, and named after the famed Niagara Falls which they share. The city is within the Buffalo–Niagara Falls Metropolitan Statistical Area as well as the Western New York region.
While the city was formerly occupied by Native Americans, Europeans who migrated to the Niagara Falls in the mid-17th century began to open businesses and develop infrastructure. Later in the 18th and 19th centuries, scientists and businessmen began harnessing the power of the Niagara River for electricity and the city began to attract manufacturers and other businesses that were drawn by the promise of inexpensive hydroelectric power. After the 1960s, however, the city and region witnessed an economic decline following an attempt at urban renewal under then Mayor Lackey, consistent with the rest of the Rust Belt as industries left the city old line affluent families relocated to nearby suburbs and out of town.
Despite the decline in heavy industry, Niagara Falls State Park and the downtown area closest to the falls continue to thrive as a result of tourism. The population, however, has continued to decline from a peak of 102,394 in the 1960s due to the loss of manufacturing jobs in the area.