| 摘要 |
An echo canceller uses a Finite-Impulse-Response (FIR) filter to remove an echo from a transmission input signal, the echo resulting from a reflection of a received signal through an echo path. An echo-cancelled signal is thereby output. The echo canceller includes impulse response estimating means for estimating the impulse response of the echo path at a time t from the received signal, the echo-cancelled signal, and the estimated impulse response signal. The estimated impulse response is output as the estimated impulse response signal. An echo signal estimating means determines a predicted signal of the echo signal from the estimated impulse response signal and the received signal, and outputs the predicted signal as an estimated echo signal. Subtractor means subtracts the estimated echo signal from the transmission signal to produce the echo cancelled signal, and the impulse response estimating means estimates the impulse response of the echo path by using the received signal and the echo cancelled signal at the time t, and the received signal and the echo cancelled signal at a time (t M) (M being a natural number).
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