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facsimile[faksim´ulE] Pronunciation Key or fax, in communications, system for transmitting pictures or other graphic matter by wire or radio. The surface of the material to be sent is traversed by a light-beam and a photodiode that translates the light and dark areas of the material thus scanned into electric signals for transmission. A receiving station reproduces the transmitted material by a variety of means. In one recording process the electric signals activate a variable lamp that is used to scan a photographic film. Newspapers and television stations use this method for recording news photographs. Facsimile is used to transmit such materials as telegrams, drawings, pictures taken from satellites, and even entire newspapers. Because of the adoption of Group 3 digital standards in 1980 by the CCITT (International Telegraph and Telephone Consultative Committee), facsimile devices have become extremely prevalent in offices. These machines work over the public telephone network; they use digital modems and transmit at data rates up to 9600 bits per second. Images are produced with a resolution of 200 dots per inch. Personal computers can emulate Group 3 facsimile machines with special plug-in circuit cards. Facsimile machines that produce higher-resolution images, or color and gray-scale images are also available.
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