Optical communication
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Optical communication, also known as optical telecommunication, is communication at a distance using light to carry information. It can be performed visually or by using electronic devices. The earlie
A naval signal lamp, a form of optical communication that uses shutters and is typically employed with Morse code (2002)
A replica of a Chappe telegraph tower (18th century)
A naval signaler transmitting a message by flag semaphore (2002).
An air traffic controller holding a signal light gun that can be used to direct aircraft experiencing a radio failure (2007).
Optical telegraph
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An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals. There are two main types of such systems: the semaphore teleg
Optical communication
…introduction to different forms of optical communication. Visual techniques such as smoke signals, beacon fires, hydraulic telegraphs, ship flags and semaphore lines were the earliest forms of optical communication. Hydraulic telegraph semaphores date back to the 4th century BCE Greece. Distress flares are still…
Illustration of signalling by semaphore in 18th-century France. The operators would move the semaphore arms to successive positions to spell out text messages in semaphore code, and the people in the next tower would read them.
An optical telegraph during World War I
19th-century demonstration of the semaphore