DIGITAL SUBSCRIBER LOOP TRANSMISSION USING ECHO CANCELLER AND BALANCING NETWORKS

摘要

This paper describes a 144 kbps subscriber loop transmission system based on a hybrid transmission technology.The automatically controlled balancing network to obtain a high return loss,the 2-stage structure of an echo canceller to reduce the precision of D/A converter and the specially formatted packetized data frame to realize a stable timing extraction characterize the system.Total system was implemented,which also has a (√f) AGC equalizer and a decision feedback type equalizer.The experiment showed the error free transmission on 4 km cable with a 0.4 mm diameter.