Media 2 - February 21, 2012 Telegraphy Telecommunication...

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February 21, 2012 Telegraphy Telecommunication before the telegraph Signal fires/smoke signals, dating to ancient Greeks talking drums 12 th BCE – fire beacons that could be seen from watch towers cannot send complex messages limited 20 mil Other methods :flags, horns, flashing mirror Optical Telegraphy Telegraph: “Distant writing” Claude Chappe coined term in 1790s Optical telegraph or semaphore system: Visual signaling system History Telegraph technology No single inventor Cooke and wheatstone, 1837 joint patent (England) Famous electrical communication Morse code in the US. Alfred vail and Samuel Morse developed a one-wire system, a simple key for sending messages, and a code of dots and dashes 1865 international Morse code standardized at international telegraphy congress went from optical to acoustic telegraphy Telegraphic codes Compression: early telegraphy was expensive, $100 for 20 words sent across transatlantic cable in 1866 Confidentiality: Unlike mail, messages were not sealed & telegraph operators saw them.
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Media 2 - February 21, 2012 Telegraphy Telecommunication...

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