Telegraphy

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telegraphy

[tə′leg·rə·fē]
(communications)
Communication at a distance by means of code signals consisting of current pulses sent over wires or by radio.

Telegraphy

 

the branch of science and technology that studies the principles of establishing telegraph communication, develops methods for transmitting telegraph signals and the equipment required by these methods, and evaluates the quality of data transmission over telegraph channels.

As a scientific and technical discipline, telegraphy is divided into the following branches, corresponding to the principal areas of interest: telegraph codes, dealing with the optimum conversion of alphameric data into combinations of electrical signals during transmission and the reciprocal conversion of the signals upon reception; terminal equipment, dealing with design principles for telegraph equipment, transmitters and reperforators, methods of signal transmission and reception, and the development of electronic equipment; telegraph channels, dealing with the most economic use of expensive wire communications and the design of channels with specific characteristics; and telegraph networks, dealing with the choice of methods for connecting subscribers and terminal points, the most advantageous distribution of stations, and the quality of subscriber services.

In order to ensure high-quality transmission in telegraphy, studies are being conducted on signal distortions, the causes and laws governing these distortions, and errors that occur during data transmission and methods of eliminating such errors.

Unlike other forms of communication, telegraphy operates with discrete messages composed of a finite number of symbols—letters, numbers, and punctuation marks. The signals that transmit these messages are also discrete. The theoretical basis of telegraphy is the general theory of communications, information theory, and the theory of potential noise immunity. Probability theory and Boolean algebra also find application in telegraphy.

Phototelegraphy is a special branch of telegraphy and has historically been included in the discipline. It studies the principles of facsimile.

References in periodicals archive ?
(3) Bruce to Curtin, Cablegram 72a, London, 11-6-1945; Commonwealth Government to Cranborne, Cablegrams 158 and 159, Canberra, 16-6-1945, in Hudson and May 1989:209-10, 215-6.
1956; see also A816, 14/301/682, Department of External Affairs (hereafter DEA) to London, cablegram 97, 17 Jan.
(60.) Cablegram, Rademeyer to Sillitoe, 15 August 1953, MI5 Personal File.
In the midst of all of the activity, on the morning of 27 April, a small tug entered Mirs Bay to deliver an urgent cablegram from Secretary Long: "War has commenced between the United States and Spain.
After things they needed to set up a program, the cablegram asked for "one qualified officer to take charge." The generals came down again and said, "Colonel David, you seem to know more about this than anybody else, you are it."
The cablegram read, "Thousands of loyal Canadians are with you in your magnificent fight to preserve the best traditions of British citizenship by resisting the coercion of Ulster.
(32) Brundage's cablegram proved impotent; the Cuban authorities were not swayed when Moenck placed it before them.
tit 8 [section] 212 (c)(2) (providing that "[a] stockholder may authorize another person or persons to act for such stockholder as proxy by transmitting or authorizing the transmission of a telegram, cablegram, or other means of electronic transmission to the person who will be the holder of the proxy").
Dear Henderson: Your cablegram indicates that you are still a bit confused.
The nicest thing about Paul Bowles is that he was a very radical young guy and I remember this Midwest magazine, perhaps it was New Left, sent out a questionnaire asking various writers what they will do if war breaks out, and asking political questions mostly, and Bowles sent them a cablegram saying, "I will have no further communication with you until I spit upon you from the cockpit of a Fokker." They printed it, and he had to disappear as a writer for a while!