| 摘要 |
An echo canceling apparatus includes a long-response echo canceler that removes an echo of an incoming signal from an outgoing signal by operating on a most recent segment of the incoming signal, stored in a tapped delay unit. The apparatus has a control unit that calculates a cancellation characteristic for each tap of the tapped delay unit. The cancellation characteristics are used to select a subset of taps corresponding to a changing component of the echo, the subset being empty if there is no changing component. A short-response echo canceler, operating on the outputs of the selected taps, cancels the changing component of the echo left uncanceled by the long-response echo canceler. Alternatively, the step gain of the selected taps is increased. The short-response echo canceler is preferably disabled in the double-talk state.
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