A D V E N T U R E S in C Y B E R S O U N DJean-Maurice-Émile Baudot : 1845 - 1903
Jean-Maurice-Émile Baudot (b. 1845, Magneux, France--d. March 28, 1903, Sceaux), engineer who, in 1874, received a patent on a telegraph code that by the mid-20th century had supplanted Morse Code as the most commonly used telegraphic alphabet. In Baudot's code, each letter was represented by a five-unit combination of current-on or current-off signals of equal duration; this represented a substantial economy over the Morse system of short dots and long dashes. Thus, 32 permutations were provided, sufficient for the Roman alphabet, punctuation signs, and control of the machine's mechanical functions. Baudot also invented (1894) a distributor system for simultaneous (multiplex) transmission of several messages on the same telegraphic circuit or channel. Modern versions of the Baudot Code usually use groups of seven or eight "on" and "off" signals. Groups of seven permit transmission of 128 characters; with groups of eight, one member may be used for error correction or other function.
The following diagram depicts a five-unit Baudot Code.
 The five-unit Baudot Code The characters depicted are the letters "W", "K", and "D". The "W" (the top character) is sent or received first
A hole in the appropriate bit position indicates a Mark (logic 1). The lack of a punched hole indicates a Space (logic 0). The smaller holes in the middle of the tape fit over a sprocket which feeds the tape through the tape punch or reader. Source: http://telecom.tbi.net
The French engineer Jean-Maurice-Émile Baudot (1845-1903), was employed by the French Telegraph Administration, to improve the efficiency of the then very slow telegraphic transmission. He had to overcome many difficulties, especially the avoidance of timing errors between phases of transmission and reception. In 1875 he devised a system which used only five keys to represent every letter of the alphabet. This was in comparison to the then current David Hughes system which used 28! In Baudot's alphabet (not code) the signals which created the letters differed not only in length but also in their respective position. Emitted signals controlled five magnets in any receiver: signals which occupied only one unit controlled only one magnet; two units, controlled two successive magnets, etc.. The keys similar to those of a piano, were lowered according to a metronome. Baudot's system also permitted two or four transmissions, depending on the importance of the line.
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