| 摘要 |
An echo canceller circuit (25) for use in an echo canceller system is set forth. The echo canceller circuit (25) comprises a first digital filter (35) having non-adaptive tap coefficients to simulate an echo response occurring during a call. A second digital filter (30) having adaptive tap coefficients to simulate an echo response occurring during the call is also used. The adaptive tap coefficients of the second digital filter (30) are updated over the duration of call. A coefficient transfer controller is disposed in the echo canceller circuit to transfer the adaptive tap coefficients of the second digital filter (30) to replace the tap coefficients of the first digital filter (35) when a value, E(~), is greater than a value, E(-), and, concurrently, when E(~), is greater than a value, E max. The value of E(-) corresponds to the ratio between a signal-plus-echo signal and a first echo compensated signal using the first digital filter. The value of E(~) corresponds to the ratio between the signal-plus-echo and a second echo compensated signal using the second digital filter (30). The value of E max corresponds to the largest E(~) experienced over at least a portion of the duration of the call and at which a transfer occurred.
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