An echo canceller having reduced word size taps and using the sign algorithm with extra controlled noise

In digital adaptive echo cancellation, the sign algorithm is very attractive since it is multiplication free. However, when the residual echo undercrosses the useful signal level, the error sign is no longer significant of the canceller quality and the convergence stops. Introduction of extra noise into the error can eliminate this drawback. The system performances regarding the residual echo and the computational complexity are shown to be competitive with those of the classical gradient algorithm (not using the function sign).