Loop Plant Electronics: Voice Frequency Electronics for Loop Applications

Abstract

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.

Electronics in the Suburban and Light Urban Loop Networks

“…6 The plan evaluated in this paper is the Concentrated Range Extender with Gain (CREG) system, which was introduced in 1979 to the Bell System on Nos. 1, 1A, 2, and 2B ESS.…”

“…Per-line range extenders have been used extensively in rural areas of the Bell System. 6 The CREG system drastically reduces the cost of range extension, which should make the system economical in subur ban applications.…”