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Loop Plant Electronics: Voice Frequency Electronics for Loop Applications

01 April 1978

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Voice Frequency Electronics for Loop Applications By G. T. HAWLEY and K. E. STIEFEL (Manuscript received October 21, 1977) Over the past 100 years the telephone loop connecting central office switching equipment and the telephone customer's premises has evolved from aerial open wire to buried plastic-insulated twisted pairs. In the last 20 years the use of electronic circuits for range extension has become popular. These circuits allow use of higher resistance loops (finer gauge wires) than central offices are normally designed to accept. This paper reviews some of this history, describes rural and suburban systems of voice frequency range extension, presents requirements and circuit design considerations, and compares several electronic range extender circuits currently used to implement these systems.