Abstract
THE transmission of pitures by land-line over various distances has been the subject of experimental development since the earliest days of telegraphic communication ; and the techniques involved have been adapted similarly for transmission or relaving over radio links. Amid the excitement of other applications in recent years, such as broadcasting, radar and television, the very advanced stage which has been attained by picture or facsimile telegraphy, as the technique is termed, is apt to be overlooked. Many systems have been suggested and experimented with ; but they have had a common basis in that the picture to be transmitted is placed on a revolving drum and scanned with a suitable source of light and optical system. The variations in light intensity reflected or scattered by the varying tones of the picture are converted into a fluctuating electric current through the agency of a photoelectric cell. The resulting signals are transmitted by line or radio to the receiving station, where they may be converted by a current-sensitive oscillograph into light variations which record the picture on suitable photographic paper. Alternatively, the electric currents are made to reproduce the picture by an electrochemical process. In either case, the recording paper is mounted on a drum which is maintained in rotation synchronously with that at the transmitting station.
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Developments in Picture Telegraphy. Nature 163, 145–146 (1949). https://doi.org/10.1038/163145a0
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DOI: https://doi.org/10.1038/163145a0