| 摘要 |
PURPOSE:To execute the assumed operation by stopping the assumed operation of an echo canceller when an input signal near the edge is increased and detecting this when the setting error difference of the threshold of a double talk detection and the change of an echo path occur. CONSTITUTION:An input edge 14 of a signal sj, in which an input near the edge is overlapped to an echo, is connected to subtracters 15 and 15' and subtracters 16 and 16'. A control part 17 executes the detection of a double talk, the setting of the threshold of a double talk detection, the transfer of an assumed impulse response between a register 18 and a register 18', the assumed operation stop of an echo canceller and the assumed operation start of the impulse response at the time of detecting the double talk. Namely, since the change of an echo path and the threshold of the double talk detection are made too small, assumption is stopped, and then, the second remaining echo is decreased and a formula is satisfied. Then, the threshold of the double talk detection is reset corresponding to the cancelling quantity when the assumption of the impulse response is continued, the echo is eliminated by using an assumed impulse response used for the calculation of the second remaining echo, and the assumed calculation of the impulse response is restarted.
|
