Telegraphy
The Telegraph Service encouraged Baudot to develop during his own time a multiple Hughes system for time-multiplexing several telegraph messages. He realised that with most printing telegraphs of the period the line is idle for most of the time, apart from the brief intervals when a character is transmitted. Baudot devised one of the first applications of time-division multiplexing in telegraphy. Using synchronized clockwork-powered switches at the transmitting and receiving ends, he was able to transmit five messages simultaneously; the system was officially adopted by the French Post & Telegraph Administration five years later.
Baudot invented his telegraph code during 1870 and patented it during 1874. It was a 5-bit code, with equal on and off intervals, which allowed telegraph transmission of the Roman alphabet, punctuation and control signals. By 1874 or 1875 (various sources give both dates) he had also perfected the electromechanical hardware to transmit his code. His inventions were based on the printing mechanism from Hughes' instrument, a distributor invented by Bernard Meyer during 1871, and the five-unit code devised by Carl Friedrich Gauss and Wilhelm Weber. Baudot combined these, together with original ideas of his own, to produce a complete multiplex system.
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