COAXIAL CABLE SYSTEM FOR TELEVISION TRANSMISSION 457 



Conclusion 



As a result of the experimental transmission of the pictures over the 

 coaxial cable from New York to Philadelphia it has been proved that 

 wide-band signals of the type required for television can be satis- 

 factorily transmitted over a coaxial cable system, and that in such 

 transmission the distortion introduced by the wire line circuits can be 

 made so small as to be inappreciable, in its effect on the received 

 picture. 



The work on these very wide-band systems has only begun and 

 repeaters and terminal apparatus are now under development capable 

 of handling wider bands of frequency. At the present time work is 

 under way on a two-million cycle system for telephone transmission 

 and a trial installation is being made between New York and Princeton. 

 The system will transmit a frequency band of about two million cycles 

 corresponding to a capacity of 480 telephone circuits. Repeaters on 

 this system will be about 5 miles apart and will consist of unattended 

 boxes somewhat smaller than the one-million cycle repeaters illustrated 

 above and placed either in manholes or on poles along the route. 

 Within these boxes there are placed two amplifiers, one for eastbound 

 transmission, the other for westbound, together with the necessary 

 filters and power supply apparatus. The actual amplifiers themselves 

 are quite small compact units one of which is shown in Fig. 16. Two 

 megacycles, of course, is not a sufficiently wide band to transmit the 

 present R.M.A. standard 441-line television signal, but is a logical 

 step toward more economical telephone circuits. Development is 

 also under way on amplifiers capable of transmitting three megacycle 

 bands of frequency, which should amply satisfy the requirements for 

 transmitting the 441-line television signals now envisioned as standard 

 by the television industry. 



References 



1. "Systems for Wide Band Transmission Over Coaxial Lines" by L. Espenschied 



and M. E. Strieby, Electrical Engineering, Vol. 53, pp. 1371-1380, October 

 1934. 



2. "A Million-Cycle Telephone System" by M. E. Strieby, Electrical Engineering, 



Vol. 56, pp. 4-7, January 1937. 



3. "A Carrier Telephone System for Toll Cables" by C. W. Green and E. I. Green, 



Bell Sys. Tech. Jour., Vol. XVII, pp. 80-105, January 1938. 



4. "Cable Carrier Telephone Terminals" by R. W. Chesnut, L. M. Ilgenfritz and 



A. Kenner, Bell Sys. Tech. Jour., Vol. XVII, pp. 106-124, January 1938. 



5. "Transmission Characteristics of the Coaxial Structure" by J. F. Wentz, Bell 



Laboratories Record, Vol. XVI, pp. 196-200, February 1938. 



