Approach to LSI implementation of a 2B1Q coded echo canceler for ISDN subscriber loop transmission

An approach to large-scale-integration (LSI) implementation of the 2B1Q echo canceler for an integrated services digital network (ISDN) basic access interface is described. A hybrid architecture, using both analog and digital processing, is adopted for LSI implementation with a moderate circuit scale. Techniques using baud-rate sampling, such as √f automatic gain control (AGC) equalization by power detection, timing extraction by peak estimation and a two-stage echo canceler with divided tables, are introduced to the system. Performance characteristics are also confirmed by computer simulation and a prototype system.