THE BELL SYSTEM 



TECHNICAL JOURNAL 



VOLUME XXXVI MARCH 1957 number 2 



Copyright 1957, American Telephone and Telegraph Company 



A New Carrier System for Rural Service 



By R. C BOYD, J. D. HOWARD, JR, and L. PEDERSEN 



(Manuscript received July 19, 1956) 



A study of the problem of providing telephone service to rural customers 

 indicated the need for a flexible carrier system that could be used economically 

 on new and existing rural cable and open wire lines. The desire for low cost 

 required new approaches to almost every phase of the carrier system design 

 for rural service, which has been designated Type PI . 



Use of transistors led to sweeping changes in the detailed circuitry and 

 also created demand for other new components. Mounting and intercon- 

 necting the circuit components by means of printed wiring boards empha- 

 sized the necessity for close coordination between design and manufacturing 

 objectives. The low power-drain requirements of t^'ansistor circuitry were 

 supplied economically by the use of similar solid state devices, a new storage 

 battery, and efficient packaging. 



A fast, accurate and simple method has been evolved for applying the PI 

 carrier system to rural lines with a minimum of line treatment or rearrange- 

 ment. Plug-in equipment, readily accessible test points, and a carrier test 

 set provide the ease of maintenance needed in the use of telephone equipment 

 at remote locations. Use of the PI carrier system will extend the application 

 of electronic equipment outside of the telephone central office and provide 

 a carrier system ivhose performance will be consistent with requirements 

 for high quality communication service at low cost. 



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