Wire Transmission System for Television

This paper deals with the transmission problems which were met and solved in connection with providing wire circuits from Washington to New York for t h e television demonstrations which took place on April 7, 1927, and following. For transmission of the television images a single transmission channel was set up combining the frequency ranges usually assigned to telegraph, telephone and certain carrier channels. T h e special line requirements were met so successfully t h a t t h e television images transmitted from Washington were indistinguishable from those transmitted locally. INTRODUCTION A S Y S T E M of television, to be worthy of the real meaning of t h e name, must be capable of operation over a considerable distance. Spanning this distance, there must be a connecting medium suitable for faithfully transmitting the television currents. This paper describes how the connecting medium was provided between Washington and New York for the recent television demonstrations, 2 by adapting to this purpose existing wire facilities of the Bell System. Fortunately, wire facilities of the type which were available between Washington and New York had been utilized for some time to transmit simultaneously m a n y telephone and telegraph messages, involving a frequency range more than ample for t h e television requirements, so t h a t the transmission characteristics of the lines throughout the necessary range of frequencies were well known. T h e m a t t e r of providing a suitable channel to carry the television currents consisted, therefore, in throwing together the frequency ranges which had heretofore been utilized for providing a number of separate telephone and telegraph channels.