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The technology typically found in motion sensors to trigger an alarm includes infrared, ultrasonic, vibration and contact. Dual technology sensors combine two or more forms of detection in order to reduce false alarms as each method has its advantages and disadvantages. Traditionally motion sensors are an integral part of a home security system.
On 18 August 1942, a day before the Dieppe raid, 'Dieppe' appeared as an answer in The Daily Telegraph crossword (set on 17 August 1942) (clued "French port"), causing a security alarm. The War Office suspected that the crossword had been used to pass intelligence to the enemy and called upon Lord Tweedsmuir , then a senior intelligence officer ...
Fire alarm bell. Fire alarm bells are divided into two categories: vibrating, and single-stroke. On a vibrating bell, the bell will ring continuously until the power is cut off. When power is supplied to a single-stroke bell, the bell will ring once and then stop. It will not ring again until power is turned off and on again.
A voice-activated radio-dispatched alarm, or VARDA-alarm, is a type of burglar alarm that, when activated or "tripped", broadcasts the type of the alarm and the transmitter location over the local police radio frequency using a pre-recorded audio message. [1] In 1968, the voice-activated radio dispatched alarm (VARDA), was invented.
The word alarm comes from the Old French a l'arme meaning "to the arms", or "to the weapons", telling armed men to pick up their weapons and get ready for action because an enemy may have suddenly appeared. [1] The word alarum is an archaic form of alarm. It was sometimes used as a call to arms in the stage directions of Elizabethan dramas. [2]
A fence-mounted perimeter intrusion detection system installed on a chain link fence. A perimeter intrusion detection system (PIDS) is a device or sensor that detects the presence of an intruder attempting to breach the physical perimeter of a property, building, or other secured area.
The Underwriters Laboratories' UL 365 is a safety standard that governs the construction, performance, and maintenance of police station-connected burglar alarm units and systems. These systems are designed primarily for use in mercantile premises, including mercantile safes and vaults, as well as bank safes and vaults.
Some forecasts project the home security market as a whole will be worth $47 billion by 2020, [12] with the DIY home security market worth $1.5 billion. [13] While the market for home security is expanding, especially with cable TV and Internet service providers introducing their own security and home automation products, it is a fragmented ...