98 



THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1957 



repeater contribution to cable noise is very small. At the lower frequen- 

 cies, while the repeater noise is considerably greater than thermal noise, 

 this does not degrade performance because of the lower cable attenua- 

 tion at these frequencies. 



MANUFACTURING DRAWINGS 



Because of the extraordinary nature of many of the manufacturing 

 problems associated with undersea repeaters it was determined at the 

 outset that a so-called single-drawing system would be used. For this 

 reason, considerably more information is supplied than is normal. The 

 effect is illustrated best in the rather large number of drawings that 

 consist of text material outlining in detail a specific manufacturing 

 technique. Such drawings specify the devices, supplies and work ma- 

 terials needed to perform an operation, and the step-by-step procedure. 

 Of course, these papers are by no means a substitute for manufacturing 

 skill. Primarily they insure the continuance of practices proved to be 

 effective with the Havana-Key West project. 



REPAIR REPEATER 



The "repair repeater," used to offset the attenuation of the excess 

 cable which must be added in making a repair, is basically the same 

 general design as the line repeater. It employs a two-stage amplifier, 

 designed to match the loss of 5.3 nautical miles of cable to within ±0.25 

 db. The larger deviation compared to the line repeater is permissible 

 since few repair repeaters are expected to be added in a cable. The input 



20 40 60 80 100 120 140 



FREQUENCY IN KILOCYCLES PER SECOND 



160 



Fig. 21 — Repeater noise. 



