bf3fe05dfb
This needs some more testing before it's on by default. If the card is otherwise functioning, these messages may be confusing to the user. If the card is not functioning, the driver can be reloaded with debug to check for this condition. Signed-off-by: Shaun Ruffell <sruffell@digium.com> git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@9205 a0bf4364-ded3-4de4-8d8a-66a801d63aff
104 lines
3.5 KiB
C
104 lines
3.5 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* ec_disable_detector.h - A detector which should eventually meet the
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* G.164/G.165 requirements for detecting the
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* 2100Hz echo cancellor disable tone.
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2001 Steve Underwood
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*
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* All rights reserved.
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*
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*/
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/*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2 as published by the
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* Free Software Foundation. See the LICENSE file included with
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* this program for more details.
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*/
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#include "biquad.h"
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#define FALSE 0
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#define TRUE (!FALSE)
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static inline void echo_can_disable_detector_init (echo_can_disable_detector_state_t *det)
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{
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/* Elliptic notch */
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/* This is actually centred at 2095Hz, but gets the balance we want, due
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to the asymmetric walls of the notch */
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biquad2_init (&det->notch,
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(int32_t) (-0.7600000*32768.0),
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(int32_t) (-0.1183852*32768.0),
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(int32_t) (-0.5104039*32768.0),
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(int32_t) ( 0.1567596*32768.0),
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(int32_t) ( 1.0000000*32768.0));
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det->channel_level = 0;
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det->notch_level = 0;
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det->tone_present = FALSE;
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det->tone_cycle_duration = 0;
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det->good_cycles = 0;
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det->hit = 0;
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}
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/*- End of function --------------------------------------------------------*/
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static inline int echo_can_disable_detector_update (echo_can_disable_detector_state_t *det,
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int16_t amp)
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{
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int16_t notched;
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notched = biquad2 (&det->notch, amp);
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/* Estimate the overall energy in the channel, and the energy in
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the notch (i.e. overall channel energy - tone energy => noise).
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Use abs instead of multiply for speed (is it really faster?).
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Damp the overall energy a little more for a stable result.
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Damp the notch energy a little less, so we don't damp out the
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blip every time the phase reverses */
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det->channel_level += ((abs(amp) - det->channel_level) >> 5);
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det->notch_level += ((abs(notched) - det->notch_level) >> 4);
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if (det->channel_level >= 70) {
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/* There is adequate energy in the channel. Is it mostly at 2100Hz? */
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if (det->notch_level*6 < det->channel_level) {
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det->tone_cycle_duration++;
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/* The notch says yes, so we have the tone. */
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if (!det->tone_present) {
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/* Do we get a kick every 450+-25ms? */
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if ((det->tone_cycle_duration >= (425 * 8)) &&
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(det->tone_cycle_duration <= (475 * 8))) {
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/* It's ANS/PR (CED with polarity reversals), so wait
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for at least three cycles before returning a hit. */
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det->good_cycles++;
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if (det->good_cycles > 2)
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det->hit = TRUE;
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}
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det->tone_cycle_duration = 0;
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det->tone_present = TRUE;
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} else if (det->tone_cycle_duration >= 600 * 8) {
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/* It's ANS (CED without polarity reversals)
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so return a hit. */
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det->hit = TRUE;
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}
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} else {
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det->tone_present = FALSE;
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}
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} else {
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det->tone_present = FALSE;
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det->tone_cycle_duration = 0;
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det->good_cycles = 0;
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}
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return det->hit;
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}
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/*- End of function --------------------------------------------------------*/
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/*- End of file ------------------------------------------------------------*/
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