| 摘要 |
PROBLEM TO BE SOLVED: To reduce a feeling of echo by a subsequent conversation even when a tone signal is input. SOLUTION: An echo canceller decides whether or not a remote-end input signal is the tone signal for controlling a call, and resets the coefficient of an adaptive filter if so. The echo canceller decides whether or not the remote-end input signal is the tone signal of a specified kind, and stops the update of the coefficient of the adaptive filter when the quantity of the echo eliminated is a threshold value or less in the case of the result of an affirmation. When the tone signal is completed, the quantities of the echo eliminated before and after the completion are compared, and the coefficient of the adaptive filter is reset and the update of the coefficient is reopened in response to the result of the comparison. Alternately, the update of the coefficient is reopened without resetting the coefficient of the adaptive filter. Band preventive filters removing the frequency component of the tone signal are fitted at input stages for the adaptive filter and an adder for eliminating the echo. COPYRIGHT: (C)2007,JPO&INPIT |
