| 摘要 |
PURPOSE:To eliminate noise produced around the boundary of each band by dividing the band into plural numbers, converting each band into a low frequency, eliminating an echo signal, restoring the frequency into the original band so as to eliminate the echo signal of all bands. CONSTITUTION:When a transmission/reception discrimination circuit 9 discriminates the mode as the reception mode, the circuit 9 throws a switch 11 to the position B and throws a switch 13 to the position D. As a result, a reception signal inputted from a terminl 23 is outputted from a speaker 17 via a band stop filter 5, a band split echo canceller 3 and an amplifier 15. In this case, the band stop filter 5 eliminates the frequency component of the band near the boundary of the band to be split by the band split echo canceller 3, then the noise around it is eliminated by using a quadrature mirror filter. The noise is elimlnated almost similarly in case of the transmiaaion.
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