The Bell System Technical Journal 



April, 1925 



The Transmission of Pictures Over 

 Telephone Lines 



By H. E. IVES and J. W. HORTON. Bell Tel. Lab. Inc. 

 R. D. PARKER and A. B. CLARK. Amer. Tel. » Tel. Co. 



Introduction 



THli probltMii of directly transmitting drawings, figures and 

 photographs froni one point to another iiy means of electricity 

 has long attracted the attention and curiosity of scientists and engi- 

 neers.' The broad principles of picture transmission have been 

 recognized for many years. Their reduction to successful practice, 

 ho\ve\er, required, among other things, the perfection of methods 

 for the faithful transmission of electrical signals to long distances, 

 and the develwpment of special ai)paratus and methods which have 

 liecome a part of the commimication art only within the last few 

 years. Prominent among the newer developments which have facil- 

 itated picture transmission are the photoelectric cell, the vacuum 

 tube amplifier, electrical filters, and the use of carrier currents. 



None of the .systems heretofore de\'ised have been sufficiently 

 developed to meet the requirements of modern commercial service. 

 The picture transmission system described in this article has been 

 designed for practical use over long distances, employing facilities 

 of the kind made a\ailable by the network of the Bell System. 



The desirability of adding picture transmission facilities to the 

 other communication facilities otTered b\' the Bell System seems now 

 to be well assured. \'arious engineers of the System have made 

 suggestions and carried out fundamental studies of the possibilities 

 for picture transmission otTered by the telephone and telegraph 

 facilities in the Bell System Plant which have aided materially in the 

 development of the method to be described. 



' .A comprehensive account of earlier work in Picture Transmission will be found 

 in "Telegraphic Transmission of Pictures," T. Thome Baker, Van Nostrand, 1910, 

 and the "llandbuch der Phototelegraphie und Telautographie," Korn and Glatzel, 

 Leipzig, Nemnich, 1911. 



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