Lines Matching +full:heart +full:- +full:rate
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.
29 The heart of the echo cancellor is FIR filter. This is adapted to match the
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),
54 high frequency content. Pre-whitening (i.e. filtering the signal to flatten its
55 spectrum) the echo signal improves the adapt rate for speech, and ensures the
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,
98 major mis-convergence in the adaption process. An assessment algorithm is