| 摘要 |
PURPOSE:To ensure the stability in a converging mode for an echo canceller which changes adaptively a tap correction coefficient, by supplying the output of an absolute value circuit to a signal conversion circuit and suppressing the variance of output of the absolute value circuit in a converging mode. CONSTITUTION:In order to delete an echo leaked into a reception circuit from a transmission circuit at the 4-wire side of a 2-wire/4-wire converting circuit, the difference signal from which the echo replica is subtracted based on the transmission signal is reduced by an adaptive filter ADF5. In this echo cancelling action, the code of the difference signal is multiplied 14 by the code of the echo replica. The value obtained from this multiplication is averaged 16. This absolute value 17 is supplied to a signal converting means 19. Then the tap correction quantity of the ADF5 is varied adaptively in response to the value 17. |
