LINE TERMINATING LSI USING ECHO CANCELLING METHOD FOR ISDN SUBSCRIBER LOOP TRANSMISSION.

A 144-kb/s digital subscriber loop (DSL) transmission system based on hybrid transmission with an echo canceling method is described. It incorporates advanced LSI technology to obtain compactness, low cost, and high reliability. An echo canceler (EC) LSI has been developed using CMOS technology. Combined with the multiplexing processor (MXP) LSI, the EC LSI provides basic DSL equipment functions. A specially arranged frame format with a newly developed digital phase-locked loop (DPLL) circuit for stable timing extraction, an automatic balancing network, and a two-stage echo canceler characterize the system. 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-kb/s bidirectional digital transmission.