Echo canceller and echo cancellation method

摘要

An echo canceller and an echo cancellation method are provided. The echo canceller includes a self-adaptive filter, a voice signal detection portion and a path change detection portion; a far-end voice signal is propagated in an echo path through a speaker and is picked up by a microphone to form an echo signal. The self-adaptive filter is configured to receive the far-end voice signal as a training signal to simulate the echo path, and cancel the echo signal in a near-end signal. The voice signal detection portion is configured to detect a communication status, control the self-adaptive filter according to the communication status, and control startup of the path change detection portion according to the communication status. The path change detection portion is configured to detect whether a change occurs on the echo path, and control the self-adaptive filter according to whether the change occurs on the echo path.

主权项

1. An echo canceller, comprising: a self-adaptive filter, a voice signal detection portion and a path change detection portion, wherein, a far-end voice signal is propagated in an echo path through a speaker and is picked up by a microphone to form an echo signal, wherein,
the self-adaptive filter is configured to receive the far-end voice signal as a training signal to simulate the echo path, and cancel the echo signal in a near-end signal; the voice signal detection portion is configured to: detect a communication status, control the self-adaptive filter according to the communication status, and control startup of the path change detection portion according to the communication status; and the path change detection portion is configured to: detect whether a change occurs on the echo path, and control the self-adaptive filter according to whether the change occurs on the echo path; wherein, an initial coefficient of the self-adaptive filter is 0; wherein the voice signal detection portion comprises a detection threshold initialization unit, a near-end voice judgment unit, a far-end voice judgment unit and a control signal sending unit, wherein: the detection threshold initialization unit is configured to: store the near-end signal when establishing the communication link, and estimate an initial value of a voice detection threshold by adopting the stored near-end signal, wherein the initial value is as an initial value of a near-end voice detection threshold of the near-end voice judgment unit and an initial value of a far-end voice detection threshold of the far-end voice judgment unit; the near-end voice judgment unit is configured to: judge whether there is a near-end voice signal, and input a result of a near-end voice judging into the control signal sending unit; the far-end voice judgment unit is configured to: judge whether there is a far-end voice signal, and input a result of a far-end voice judging into the control signal sending unit; and the control signal sending unit is configured to: send a control signal to control the self-adaptive filter and the path change detection portion after receiving the result of the near-end voice judging and the result of the far-end voice judging; wherein, the control signal send unit is configured to send the control signal to control the self-adaptive filter and the path change detection portion according to the following way: closing the self-adaptive filter during a near-end communication or muting; locking the self-adaptive filter during a double-end communication, which is equivalent to not updating coefficients of the self-adaptive filter; starting the path change detection portion during non near-end communication, non-muting, and non double-end communication; wherein, the near-end voice judgment unit is configured to judge whether there is a near-end voice signal according to the following way: adding 1 to a counter C(n) when d1 (n)2>Threshold, and judging that there is the near-end voice signal in the near-end signal whenSUMC=∑i=MM+N1-1⁢C⁡(i)>Threshold⁢⁢2,  wherein, d1 (n) is a convolution of coefficients of the first L orders of the self-adaptive filter and the far-end voice signal, the Threshold is a first near-end voice detection threshold, and the Threshold2 is a second near-end voice detection threshold, Ni is a length of a sliding window, M=M+S, wherein M is a starting point of the sliding window and S is a sliding length of the sliding window; or, adding 1 to the counter C(n)when∑i=1N3⁢d⁡(i)2>Threshold,  and judging that there is the near-end voice signal in the near-end signal whenSUMC=∑i=MM+N1-1⁢C⁡(i)>Threshold⁢⁢2,wherein, d(n) is the near-end signal, N3 is a frame length, the Threshold is the first near-end voice detection threshold, and the Threshold2 is the second near-end voice detection threshold, Ni is a length of the sliding window, M=M+S, wherein M is the starting point of the sliding window and S is the sliding length of the sliding window;
the far-end voice judgment unit is configured to judge whether there is a far-end voice signal according to the following way: adding 1 to a counter D(n) when x(n)2>Threshold1, and judging that there is the far-end voice signal in the far-end signal whenSUMD=∑i=MM+N2-1⁢D⁡(i)>Threshold⁢⁢3,  wherein, the Threshold1 is a first far-end voice detection threshold, the Threshold3 is a second far-end voice detection threshold, and N2 is a length of a sliding window; wherein, the first near-end voice detection threshold is equal to the first far-end voice detection threshold, and the second near-end voice detection threshold is equal to the second far-end voice detection threshold.