Echo canceler employing multiple step gains

摘要

According to a first aspect of the invention, in an echo canceler having an adaptive filter, the tap coefficients of the adaptive filter are partitioned into at least two segments, and different step gains are assigned to different segments. The step gains are used in adjusting the tap coefficients, and determine the sensitivity of the adjustment to noise in the residual signal left after echo cancellation. Comparatively small step gains are assigned to noise-sensitive segments. According to a second aspect of the invention, the step gain is switched according to the level of local background noise. <IMAGE>