PLANNING AND OVER-ALL PERFORMANCE 



27 





o 



i < 



I 2 



^ 20 30 40 60 80 100 200 300 400 600 1000 2000 



FREQUENCY IN CYCLES PER SECOND 



4000 



10,000 



Fig. 7 — Frequency characteristic of typical program channel, London-New York. 



at 120 cycles and frequency modulation. The telegraph distortion due 

 to the cable system with start stop signals is about 4 per cent in every 

 case, thus making the circuits suitable for switched connections, without 

 regeneration, up to the same limits as inland systems. 



Tests over the system indicate that the channel speed can be raised 

 satisfactorily to 80 bauds on at least ten of the channels. By the adoption 

 of synchronous working, it appears that time division multiplex systems 

 can be operated on these ten channels to double their capacity at a later 

 date. 



CONCLUSION 



The transatlantic cable system has presented unique problems in sys- 

 tem planning and design. It has been necessary to design the system 

 to connect the facilities of many countries and to provide for cable com- 

 munication of unprecedented length. But the stringent design objectives 

 necessary to meet these requirements have not been the only challenge 

 to the designer. It has been necessary to meet these objectives with a 

 system which for over 2,000 miles of its length could not be altered to 

 the slightest extent once it had been placed on the ocean bottom. Except 

 for the adjustments which can be made at the shore terminals of the 

 submarine links it has not been permissible to make any of the multitude 

 of small design changes, substitutions and adaptations which are so 

 commonly required in new systems to achieve the design objectives. 



The success achieved in meeting the original objectives is a measure of 

 the realism of the early planning as well as the diligence with which the 

 project was carried forward to completion and is a tribute to all who 

 took part in planning, designing and building the system. 



The accomplishment of getting into commercial service a working 

 system with many complex links six weeks after the final splice was 

 dropped overboard, and nearly ten weeks ahead of schedule, is a further 

 tribute to the close cooperation of the technical people of three nations. 



