Antonelli, Terry & Wands
PCM coder and decoder circuit having digital balancing network
 A PCM coder and decoder circuit for use in a subscriber line interface circuit of a telephone communication system has a digital balancing network for removing any echo signal. The digital balancing network is formed by series-connecting a first balancing circuit having characteristics corresponding to the fixed characteristics of a coder, decoder, etc. and a second balancing circuit having characteristics corresponding to variable characteristics of an external circuit including two-wire transmission line which is connected to the coder and decoder circuit. Thus, a replica of an echo signal is precisely produced, and the circuit configuration is simplified. 
Hitachi Ltd. Hitachi Micro Computer Eng. Ltd.
H H
H04M H04B
inventional inventional
Kenichi Kazuo Takahiko Shigeo
Ohwada Yamakido Kozaki Nishita