Telephonic communications – Echo cancellation or suppression – Using digital signal processing
Reexamination Certificate
2005-09-20
2005-09-20
Tran, Sinh (Department: 2644)
Telephonic communications
Echo cancellation or suppression
Using digital signal processing
C379S406010, C379S406020, C379S405000, C379S406050, C379S406070, C379S406080, C379S406090
Reexamination Certificate
active
06947553
ABSTRACT:
A communication system being made up of a two-wire/four-wire hybrid circuit, an echo canceller, and a control device and having functions of forming a plurality of communication paths and changing communication paths is provided which is capable of ensuring high speech quality by suppressing and canceling an echo occurring in telephone speech after establishment of path connection. The communication system also includes a training signal source to feed a training signal to the echo canceller, a switching circuit to do switching of a signal to be fed to the echo canceller between an ordinary signal and the training signal, and a control device to exert control on path connection and path changing and to feed the training signal to the switching circuit to make a training signal be fed from the training signal source to the echo canceller and to have the echo canceller converge its training operation.
REFERENCES:
patent: 5414763 (1995-05-01), Hirata
patent: 5740242 (1998-04-01), Hayashi
patent: 6147979 (2000-11-01), Michel et al.
patent: 3-188718 (1991-08-01), None
Koyama Kazuhiko
Suzuki Kazuya
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Singh Ramnandan
Tran Sinh
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