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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.
Edmonds
Edmonds is a city in Snohomish County, Washington, United States, and is a Northern Suburb of Seattle located 11 miles (18 km) north of the city. Edmonds has a view of Puget Sound and both the Olympic Mountains and Cascade Range. The third most populous city in Snohomish County after Everett and Marysville, the population was 39,709 according to the 2010 census and the estimated population in 2015 was 40,490.[3] Based on per capita income, one of the more reliable measures of affluence, Edmonds ranks 20th of 281 areas in the state of Washington.[5]
Edmonds is a port in the Washington State Ferries system. Currently, the only ferry from Edmonds is a run to Kingston, Washington; in the past, there have been much longer routes from Edmonds to Port Townsend, Washington.[6]
Edmonds is the oldest incorporated city in Snohomish County. Logger George Brackett founded Edmonds in 1890, naming the city either for Vermont Sen. George Franklin Edmunds[7] or in association with the nearby Point Edmund, named by Charles Wilkes in 1841 and later changed to Point Edwards.[8] Brackett came to the future site of Edmonds while paddling a canoe north of Seattle, searching for timber. When a gust of wind hit his canoe, Brackett beached in a location later called “Brackett’s Landing”.[9]
The town was named Edmonds in 1884, but was not incorporated until 1890 as an official “village fourth class” of Snohomish County. In that same year, Brackett sold 455 acres (1.84 km2) to the Minneapolis Realty and Investment Company. The town was plotted and a wharf was added along the waterfront. Modest houses and commercial structures sprouted up with a row of shingle mills dominating the cityscape.