Lines Matching +full:pre +full:- +full:its

1 /* SPDX-License-Identifier: GPL-2.0-only */
3  * SpanDSP - a series of DSP components for telephony
5  * echo.c - A line echo canceller.  This code is being developed
24 This module aims to provide G.168-2002 compliant echo cancellation, to remove
25 electrical echoes (e.g. from 2-4 wire hybrids) from voice calls.
43 varies widely.  This is quite easy to fix. If the signal level is normalised -
44 similar to applying AGC - LMS can work as well for a signal of varying
47 other algorithms exist - e.g. RLS (essentially the same as Kalman filtering),
51 A simple refinement to NLMS can improve its performance with speech. NLMS tends
54 high frequency content. Pre-whitening (i.e. filtering the signal to flatten its
57 low complexity filter is adequate for this, so pre-whitening adds little to the
60 An FIR filter adapted using pre-whitened NLMS performs well, provided certain
63     - The transmitted signal has poor self-correlation.
64     - There is no signal being generated within the environment being
74 random signal - the impulse response of the line. For a repetitive signal,
79 continue converging on such energy is just a way to ruin its generalised
98 major mis-convergence in the adaption process. An assessment algorithm is