Closed-circuit television (CCTV), also known as video surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point-to-point (P2P), point-to-multipoint (P2MP), or mesh wired or wireless links. Even though almost all video cameras fit this definition, the term is most often applied to those used for surveillance in areas that require additional security or ongoing monitoring (Videotelephony is seldom called "CCTV").
Surveillance of the public using CCTV is common in many areas around the world. Video surveillance has generated significant debate about balancing its use with individuals' right to privacy even when in public.
In industrial plants, CCTV equipment may be used to observe parts of a process from a central control room, especially if the environments observed are dangerous or inaccessible to humans. CCTV systems may operate continuously or only as required to monitor a particular event. A more advanced form of CCTV, using digital video recorders (DVRs), provides recording for possibly many years, with a variety of quality and performance options and extra features (such as motion detection and email alerts). More recently, decentralized IP cameras, perhaps equipped with megapixel sensors, support recording directly to network-attached storage devices, or internal flash for completely stand-alone operation.
By one estimate, there will be approximately 1 billion surveillance cameras in use worldwide by 2021.[needs update] About 65% of these cameras are installed in Asia. The growth of CCTV has been slowing in recent years.[unreliable source?] The deployment of this technology has facilitated significant growth in state surveillance, a substantial rise in the methods of advanced social monitoring and control, and a host of crime prevention measures throughout the world.
A security alarm is a system designed to detect intrusions, such as unauthorized entry, into a building or other areas, such as a home or school. Security alarms protect against burglary (theft) or property damage, as well as against intruders. Examples include personal systems, neighborhood security alerts, car alarms, and prison alarms.
Some alarm systems serve a single purpose of burglary protection; combination systems provide fire and intrusion protection. Intrusion-alarm systems are combined with closed-circuit television surveillance (CCTV) systems to record intruders' activities and interface to access control systems for electrically locked doors. There are many types of security systems. Homeowners typically have small, self-contained noisemakers. These devices can also be complicated, multirole systems with computer monitoring and control. It may even include a two-way voice which allows communication between the panel and monitoring station.
Devizes (/dɪˈvaɪzɪz/) is a market town and civil parish in Wiltshire, England. It developed around Devizes Castle, an 11th-century Norman castle, and received a charter in 1141. The castle was besieged during the Anarchy, a 12th-century civil war between Stephen of England and Empress Matilda, and again during the English Civil War when the Cavaliers lifted the siege at the Battle of Roundway Down. Devizes remained under Royalist control until 1645, when Oliver Cromwell attacked and forced the Royalists to surrender. The castle was destroyed in 1648 on the orders of Parliament, and today little remains of it.
From the 16th century Devizes became known for its textiles, and by the early 18th century it held the largest corn market in the West Country, constructing the Corn Exchange in 1857. In the 18th century, brewing, curing of tobacco, and snuff-making were established. The Wadworth Brewery was founded in the town in 1875.
Standing at the west edge of the Vale of Pewsey, the town is about 10.5 miles (16.9 km) southeast of Chippenham and 11 miles (18 km) north-east of the county town of Trowbridge. It has nearly five hundred listed buildings, some notable churches, a town hall and a green in the centre.