ECHO CANCELLER
PURPOSE:To reduce the leakage of an audio signal and an in-band ringer signal by providing an adaptive digital filer for audio signal and the one for in-band ringer signal at an echo canceller on a transmission line, and updating only the filter coefficient of either of the adaptive digital filters....
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Zusammenfassung: | PURPOSE:To reduce the leakage of an audio signal and an in-band ringer signal by providing an adaptive digital filer for audio signal and the one for in-band ringer signal at an echo canceller on a transmission line, and updating only the filter coefficient of either of the adaptive digital filters. CONSTITUTION:Control signals SS, SR supplied from a PBX to an in-band ringer 20 are inputted to an in-band ringer control part 20a, and when no communication, i.e., the input of an SS signal is detected, the digital filter coefficient of a false echo generator 27 for in-band ringer signal is updated. Therefore, the filter coefficient capable of sufficiently suppressing the leakage of the in- band ringer signal can be set. At this time, the filter coefficient of an echo generator 28 for audio signal is not updated. While, when the control signal SR representing a speech state is inputted from the PBX to the ringer 20, a signal is supplied from the control part 20a to the generator 28, and the filter coefficient of the generator 28 is updated. |
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