ISDN subscriber loop transmission LSl using echo cancelling method

This paper describes a 144 kbit/s digital subscriber loop (DSL) transmission system based on hybrid-mode transmission with an echo canceling method. It uses advanced LSI technology to obtain compactness, low cost, and high reliability. An echo canceller (EC) LSI has been developed using CMOS technology. Combined with the multiplexing processor (MXP) LSI, the EC LSI provides basic DSL equipment functions. The system consists of a specially arranged frame format with a newly developed DPLL circuit for stable timing extraction, and automatic balancing nextwork, and a two-stage echo canceller. Using this line termination circuit, the DSL equipment showed a reach of over 6 km when used with 0.5 mm diameter cable for 160 kbit/s bidirectional digital transmission.