Television Transmission Over Wire Lines* 



By M. E. STRIEBY and J. F. WENTZ 



Intercity networks appear vital to the success of television broad- 

 casting. Experiments with wire lines for this purpose and for local 

 transmission of present-day television signals are reported herein. The 

 design and construction of the equipment used are described and its 

 performance characteristics given. 



The intercity lines discussed involve carrier transmission over coaxial 

 cable with repeaters which pass a net band of about 2f megacycles. For 

 local intracity connections video transmission of about a 4 mc band is 

 obtained over existing telephone plant or by means of special low at- 

 tenuation cable. Various circuit arrangements including the facilities 

 used in bringing scenes from the Republican Convention in Philadelphia 

 to the N.B.C. in New York are shown together with their overall tele- 

 vision transmission characteristics. 



Introduction 



IF THE development of television broadcasting follows in the footsteps 

 of its predecessor in the sound broadcasting field, networks for inter- 

 connecting television stations will be very important. In fact many 

 students^ of the problem believe that such networks are a virtual necessity 

 because of the expected high cost of programs. 



Considerable progress in the development of a wire line technique for 

 this purpose has been made in connection with the Bell System's study of 

 coaxial conductor systems for use in wide band telephony. Data previously 

 published^ ■ ^ • ^ have been supplemented recently by certain tests and 

 experiments in the transmission of 441-line television images, the results 

 of which are presented in this paper. This will cover the transmission 

 characteristics of facilities both for intercity and local distribution, in- 

 cluding the wire lines which were used during the television broadcast in 

 New York of the proceedings of the Republican Convention in Philadelphia 

 during the last week of June, 1940. This broadcast was undertaken jointly 

 by the National Broadcasting Company and Bell System Companies as an 

 experiment in the furtherance of the television art. A large part of the 

 experimental facilities used were manufactured by the Western Electric 

 Company. 



Long Haul Coaxial Systems 



For long-distance broad-band transmission, coaxial systems have certain 

 natural advantages which have been previously pointed out. In common 

 * Presented before the A.I.E.E., January 30, 1940. 



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