| 摘要 |
PURPOSE:To decrease the scale of hardware for the entire device by providing an adaptive filter eliminating echo while a positive/negative pulse is to be regarded symmetrical and an adaptive filter eliminating echo due to the asymmetricity of the positive/negative pulse so as to decrease the required memory capacity. CONSTITUTION:Two adaptive filters 9, 10 are used as adaptive filters to eliminate echo and a data converting circuit 8 and an adder 11 are provided. The adaptive filter 9 receives a signal supplied from a coder 2 to generate a 1st echo replica. The adaptive filter 10 receives an output of a data conversion circuit 8 converting a signal supplied from the coder 2 to generate a 2nd echo replica. The adder 11 obtains the sum of the 1st echo replica and the 2nd echo replica and a subtractor 5' subtracts the output of the adder 11 from a mixed signal where the echo and the reception signal exist in mixture. The output of the subtractor 5' is used to make the adaptive filters 9, 10 adpative to eliminate the echo.
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