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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.
Spokane
Spokane (
i/spoʊˈkæn/ spoh-kan)[7] is a city in the state of Washington, in the northwestern United States. It is the seat of Spokane County, and the economic and cultural center of the Spokane Metropolitan Area, the Greater Spokane Area, and the Inland Northwest. It is located along the Spokane River west of the Rocky Mountain foothills in eastern Washington, 92 miles (148 km) south of the Canada–US border, approximately 20 miles (30 km) from the Washington–Idaho border, and 280 miles (450 km) east of Seattle along Interstate 90. The city, along with the whole Inland Northwest, is served by Spokane International Airport, 5 miles (8 km) west of downtown Spokane. According to the 2010 Census, Spokane had a population of 208,916, making it the second largest city in Washington and the 102nd largest city in the United States.
The first humans to live in the area, the Spokane people (their name meaning “children of the sun” in Salishan), arrived between 13,000 and 8,000 years ago, living off plentiful game. Known as the birthplace of Father’s Day, Spokane is officially nicknamed the “Lilac City”. David Thompson explored the area with the westward expansion and establishment of the North West Company‘s Spokane House in 1810. This trading post was the first long-term European settlement in Washington. Completion of the Northern Pacific Railway in 1881 brought settlers to the Spokane area, and that same year it was officially incorporated as a city with the name of “Spokan Falls”. In the late 19th century, gold and silver were discovered in the Inland Northwest. The local economy depended on mining, timber, and agriculture until the 1980s. Spokane hosted the first environmentally themed World’s Fair at Expo ’74.