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5
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1 /*
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2 * SpanDSP - a series of DSP components for telephony
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3 *
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4 * modem_echo_tests.c
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5 *
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6 * Written by Steve Underwood <steveu@coppice.org>
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7 *
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8 * Copyright (C) 2004 Steve Underwood
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9 *
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10 * All rights reserved.
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11 *
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12 * This program is free software; you can redistribute it and/or modify
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13 * it under the terms of the GNU General Public License version 2, as
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14 * published by the Free Software Foundation.
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15 *
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16 * This program is distributed in the hope that it will be useful,
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17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 * GNU General Public License for more details.
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20 *
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21 * You should have received a copy of the GNU General Public License
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22 * along with this program; if not, write to the Free Software
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23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 *
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25 * $Id: modem_echo_tests.c,v 1.22 2006/11/19 14:07:27 steveu Exp $
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26 */
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27
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28 /*! \page modem_echo_can_tests_page Line echo cancellation for modems tests
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29 \section modem_echo_can_tests_page_sec_1 What does it do?
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30 Currently the echo cancellation tests only provide simple exercising of the
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31 cancellor in the way it might be used for line echo cancellation. The test code
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32 is in echotests.c.
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33
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34 The goal is to test the echo cancellor again the G.16X specs. Clearly, that also
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35 means the goal for the cancellor itself is to comply with those specs. Right
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36 now, the only aspect of these tests implemented is the line impulse response
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37 models in g168tests.c.
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38
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39 \section modem_echo_can_tests_page_sec_2 How does it work?
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40 The current test consists of feeding a wave file of real speech to the echo
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41 cancellor as the transmit signal. A very simple model of a telephone line is
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42 used to simulate a simple echo from the transmit signal. A second wave file of
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43 real speech is also used to simulate a signal received form the far end of the
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44 line. This is gated so it is only placed for one second every 10 seconds,
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45 simulating the double talk condition. The resulting echo cancelled signal can
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46 either be store in a file for further analysis, or played back as the data is
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47 processed.
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48
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49 A number of modified versions of this test have been performed. The signal level
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50 of the two speech sources has been varied. Several simple models of the
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51 telephone line have been used. Although the current cancellor design has known
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52 limitations, it seems stable for all these test conditions. No instability has
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53 been observed in the current version due to arithmetic overflow when the speech
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54 is very loud (with earlier versions, well, ....:) ). The lack of saturating
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55 arithmetic in general purpose CPUs is a huge disadvantage here, as software
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56 saturation logic would cause a major slow down. Floating point would be good,
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57 but is not usable in the Linux kernel. Anyway, the bottom line seems to be the
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58 current design is genuinely useful, if imperfect.
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59
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60 \section modem_echo_can_tests_page_sec_2 How do I use it?
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61
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62 Build the tests with the command "./build". Currently there is no proper make
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63 setup, or way to build individual tests. "./build" will built all the tests
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64 which currently exist for the DSP functions. The echo cancellation test assumes
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65 there are two wave files containing mono, 16 bit signed PCM speech data, sampled
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66 at 8kHz. These should be called local_sound.wav and far_sound.wav. A third wave
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67 file will be produced. This very crudely starts with the first 256 bytes from
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68 the local_sound.wav file, followed by the results of the echo cancellation. The
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69 resulting audio is also played to the /dev/dsp device. A printf near the end of
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70 echo_tests.c is commented out with a \#if. If this is enabled, detailed
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71 information about the results of the echo cancellation will be written to
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72 stdout. By saving this into a file, Grace (recommended), GnuPlot, or some other
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73 plotting package may be used to graphically display the functioning of the
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74 cancellor.
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75 */
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76
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77 #ifdef HAVE_CONFIG_H
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78 #include "config.h"
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79 #endif
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80
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81 #if defined(HAVE_FL_FL_H) && defined(HAVE_FL_FL_CARTESIAN_H) && defined(HAVE_FL_FL_AUDIO_METER_H)
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82 #define ENABLE_GUI
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83 #endif
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84
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85 #include <stdlib.h>
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86 #include <inttypes.h>
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87 #include <string.h>
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88 #include <time.h>
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89 #include <stdio.h>
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90 #include <fcntl.h>
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91 #include <audiofile.h>
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92 #include <tiffio.h>
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93 #if defined(HAVE_TGMATH_H)
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94 #include <tgmath.h>
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95 #endif
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96 #if defined(HAVE_MATH_H)
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97 #define GEN_CONST
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98 #include <math.h>
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99 #endif
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100
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101 #include "spandsp.h"
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102 #include "spandsp/g168models.h"
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103 #if defined(ENABLE_GUI)
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104 #include "echo_monitor.h"
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105 #endif
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106
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107 #if !defined(NULL)
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108 #define NULL (void *) 0
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109 #endif
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110
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111 typedef struct
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112 {
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113 const char *name;
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114 int max;
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115 int cur;
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116 AFfilehandle handle;
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117 int16_t signal[8000];
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118 } signal_source_t;
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119
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120 signal_source_t local_css;
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121
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122 fir32_state_t line_model;
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123
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124 AFfilehandle resulthandle;
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125 int16_t residue_sound[8000];
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126 int residue_cur = 0;
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127 int do_codec_munge = TRUE;
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128 int use_gui = FALSE;
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129
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130 static const int16_t tone_1khz[] = {10362, 7327, 0, -7327, -10362, -7327, 0, 7327};
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131
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132 static inline void put_residue(int16_t tx, int16_t residue)
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133 {
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134 int outframes;
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135
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136 residue_sound[residue_cur++] = tx;
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137 residue_sound[residue_cur++] = residue;
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138 if (residue_cur >= 8000)
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139 {
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140 residue_cur >>= 1;
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141 outframes = afWriteFrames(resulthandle,
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142 AF_DEFAULT_TRACK,
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143 residue_sound,
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144 residue_cur);
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145 if (outframes != residue_cur)
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146 {
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147 fprintf(stderr, " Error writing residue sound\n");
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148 exit(2);
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149 }
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150 residue_cur = 0;
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151 }
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152 }
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153 /*- End of function --------------------------------------------------------*/
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154
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155 static void signal_load(signal_source_t *sig, const char *name)
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156 {
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157 float x;
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158
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159 sig->name = name;
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160 if ((sig->handle = afOpenFile(sig->name, "r", 0)) == AF_NULL_FILEHANDLE)
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161 {
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162 fprintf(stderr, " Cannot open sound file '%s'\n", sig->name);
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163 exit(2);
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164 }
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165 if ((x = afGetFrameSize(sig->handle, AF_DEFAULT_TRACK, 1)) != 2.0)
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166 {
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167 fprintf(stderr, " Unexpected frame size in wave file '%s'\n", sig->name);
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168 exit(2);
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169 }
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170 if ((x = afGetRate(sig->handle, AF_DEFAULT_TRACK)) != (float) SAMPLE_RATE)
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171 {
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172 printf(" Unexpected sample rate in wave file '%s'\n", sig->name);
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173 exit(2);
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174 }
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175 if ((x = afGetChannels(sig->handle, AF_DEFAULT_TRACK)) != 1.0)
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176 {
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177 printf(" Unexpected number of channels in wave file '%s'\n", sig->name);
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178 exit(2);
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179 }
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180 sig->max = afReadFrames(sig->handle, AF_DEFAULT_TRACK, sig->signal, 8000);
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181 if (sig->max < 0)
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182 {
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183 fprintf(stderr, " Error reading sound file '%s'\n", sig->name);
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184 exit(2);
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185 }
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186 }
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187 /*- End of function --------------------------------------------------------*/
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188
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189 static void signal_free(signal_source_t *sig)
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190 {
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191 if (afCloseFile(sig->handle) != 0)
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192 {
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193 fprintf(stderr, " Cannot close sound file '%s'\n", sig->name);
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194 exit(2);
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195 }
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196 }
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197 /*- End of function --------------------------------------------------------*/
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198
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199 static void signal_restart(signal_source_t *sig)
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200 {
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201 sig->cur = 0;
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202 }
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203 /*- End of function --------------------------------------------------------*/
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204
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205 static int16_t signal_amp(signal_source_t *sig)
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206 {
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207 int16_t tx;
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208
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209 tx = sig->signal[sig->cur++];
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210 if (sig->cur >= sig->max)
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211 sig->cur = 0;
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212 return tx;
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213 }
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214 /*- End of function --------------------------------------------------------*/
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215
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216 static inline int16_t codec_munge(int16_t amp)
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217 {
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218 if (do_codec_munge)
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219 return alaw_to_linear(linear_to_alaw(amp));
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220 return amp;
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221 }
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222 /*- End of function --------------------------------------------------------*/
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223
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224 static void channel_model_create(int model)
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225 {
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226 static const int32_t *line_models[] =
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227 {
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228 line_model_d2_coeffs,
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229 line_model_d3_coeffs,
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230 line_model_d4_coeffs,
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231 line_model_d5_coeffs,
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232 line_model_d6_coeffs,
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233 line_model_d7_coeffs,
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234 line_model_d8_coeffs,
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235 line_model_d9_coeffs
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236 };
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237
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238 static int line_model_sizes[] =
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239 {
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240 sizeof(line_model_d2_coeffs)/sizeof(int32_t),
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241 sizeof(line_model_d3_coeffs)/sizeof(int32_t),
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242 sizeof(line_model_d4_coeffs)/sizeof(int32_t),
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243 sizeof(line_model_d5_coeffs)/sizeof(int32_t),
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244 sizeof(line_model_d6_coeffs)/sizeof(int32_t),
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245 sizeof(line_model_d7_coeffs)/sizeof(int32_t),
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246 sizeof(line_model_d8_coeffs)/sizeof(int32_t),
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247 sizeof(line_model_d9_coeffs)/sizeof(int32_t)
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248 };
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249
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250 fir32_create(&line_model, line_models[model], line_model_sizes[model]);
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251 }
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252 /*- End of function --------------------------------------------------------*/
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253
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254 static int16_t channel_model(int16_t local, int16_t far)
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255 {
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256 int16_t echo;
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257 int16_t rx;
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258
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259 /* Channel modelling is merely simulating the effects of A-law distortion
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260 and using one of the echo models from G.168 */
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261
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262 /* The local tx signal will have gone through an A-law munging before
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263 it reached the line's analogue area where the echo occurs. */
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264 echo = fir32(&line_model, codec_munge(local/8));
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265 /* The far end signal will have been through an A-law munging, although
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266 this should not affect things. */
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267 rx = echo + codec_munge(far);
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268 /* This mixed echo and far end signal will have been through an A-law munging when it came back into
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269 the digital network. */
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270 rx = codec_munge(rx);
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271 return rx;
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272 }
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273 /*- End of function --------------------------------------------------------*/
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274
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275 int main(int argc, char *argv[])
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276 {
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277 modem_echo_can_state_t *ctx;
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278 //awgn_state_t local_noise_source;
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279 awgn_state_t far_noise_source;
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280 int i;
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281 int clean;
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282 int16_t rx;
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283 int16_t tx;
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284 int local_cur;
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285 int far_cur;
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286 int result_cur;
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287 AFfilesetup filesetup;
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288 int line_model_no;
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289 time_t now;
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290 power_meter_t power_before;
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291 power_meter_t power_after;
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292 float unadapted_output_power;
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293 float unadapted_echo_power;
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294 float adapted_output_power;
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295 float adapted_echo_power;
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296 #if defined(ENABLE_GUI)
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297 int16_t amp[2];
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298 #endif
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299
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300 line_model_no = 0;
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301 use_gui = FALSE;
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302 for (i = 1; i < argc; i++)
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303 {
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304 if (strcmp(argv[i], "-g") == 0)
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305 {
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306 use_gui = TRUE;
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307 continue;
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308 }
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309 line_model_no = atoi(argv[1]);
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310 }
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311 time(&now);
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312 ctx = modem_echo_can_create(256);
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313 awgn_init_dbm0(&far_noise_source, 7162534, -50.0f);
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314
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315 signal_load(&local_css, "sound_c1_8k.wav");
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316
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317 filesetup = afNewFileSetup();
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318 if (filesetup == AF_NULL_FILESETUP)
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319 {
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320 fprintf(stderr, " Failed to create file setup\n");
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321 exit(2);
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322 }
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323 afInitSampleFormat(filesetup, AF_DEFAULT_TRACK, AF_SAMPFMT_TWOSCOMP, 16);
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324 afInitRate(filesetup, AF_DEFAULT_TRACK, (float) SAMPLE_RATE);
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325 afInitFileFormat(filesetup, AF_FILE_WAVE);
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326 afInitChannels(filesetup, AF_DEFAULT_TRACK, 2);
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327
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328 resulthandle = afOpenFile("modem_echo.wav", "w", filesetup);
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329 if (resulthandle == AF_NULL_FILEHANDLE)
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330 {
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331 fprintf(stderr, " Failed to open result file\n");
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332 exit(2);
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333 }
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334
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335 #if defined(ENABLE_GUI)
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336 if (use_gui)
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337 start_echo_can_monitor(256);
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338 #endif
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339
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340 local_cur = 0;
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341 far_cur = 0;
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342 result_cur = 0;
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343 channel_model_create(line_model_no);
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344 #if defined(ENABLE_GUI)
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345 if (use_gui)
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346 echo_can_monitor_line_model_update(line_model.coeffs, line_model.taps);
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347 #endif
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348
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349 modem_echo_can_flush(ctx);
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350
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351 power_meter_init(&power_before, 5);
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352 power_meter_init(&power_after, 5);
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353
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354 /* Measure the echo power before adaption */
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355 modem_echo_can_adaption_mode(ctx, FALSE);
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356 for (i = 0; i < 8000*5; i++)
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357 {
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358 tx = tone_1khz[i & 7];
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359 rx = channel_model(tx, 0);
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360 clean = modem_echo_can_update(ctx, tx, rx);
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361 power_meter_update(&power_before, rx);
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362 power_meter_update(&power_after, clean);
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363 }
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364 unadapted_output_power = power_meter_dbm0(&power_before);
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365 unadapted_echo_power = power_meter_dbm0(&power_after);
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366 printf("Pre-adaption: output power %10.5fdBm0, echo power %10.5fdBm0\n", unadapted_output_power, unadapted_echo_power);
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367
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368 /* Converge the canceller */
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369 signal_restart(&local_css);
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370 modem_echo_can_adaption_mode(ctx, TRUE);
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371 for (i = 0; i < 800*2; i++)
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372 {
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373 clean = modem_echo_can_update(ctx, 0, 0);
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374 put_residue(0, clean);
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375 }
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376
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377 for (i = 0; i < 8000*50; i++)
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378 {
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379 tx = signal_amp(&local_css);
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380 rx = channel_model(tx, 0);
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381 clean = modem_echo_can_update(ctx, tx, rx);
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382 power_meter_update(&power_before, rx);
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383 power_meter_update(&power_after, clean);
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384 #if 0
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385 if (i%800 == 0)
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386 printf("Powers %10.5fdBm0 %10.5fdBm0\n", power_meter_dbm0(&power_before), power_meter_dbm0(&power_after));
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387 #endif
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388 put_residue(tx, clean);
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389 #if defined(ENABLE_GUI)
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390 if (use_gui)
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391 {
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392 echo_can_monitor_can_update(ctx->fir_taps16, 256);
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393 amp[0] = tx;
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394 echo_can_monitor_line_spectrum_update(amp, 1);
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395 }
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396 #endif
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397 }
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398
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399 /* Now lets see how well adapted we are */
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400 modem_echo_can_adaption_mode(ctx, FALSE);
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401 for (i = 0; i < 8000*5; i++)
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402 {
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403 tx = tone_1khz[i & 7];
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404 rx = channel_model(tx, 0);
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405 clean = modem_echo_can_update(ctx, tx, rx);
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406 power_meter_update(&power_before, rx);
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407 power_meter_update(&power_after, clean);
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|
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408 }
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409 adapted_output_power = power_meter_dbm0(&power_before);
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410 adapted_echo_power = power_meter_dbm0(&power_after);
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411 printf("Post-adaption: output power %10.5fdBm0, echo power %10.5fdBm0\n", adapted_output_power, adapted_echo_power);
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|
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412
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|
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413 if (fabsf(adapted_output_power - unadapted_output_power) > 0.1f
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|
414 ||
|
|
|
415 adapted_echo_power > unadapted_echo_power - 30.0f)
|
|
|
416 {
|
|
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417 printf("Tests failed.\n");
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|
|
418 exit(2);
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|
|
419 }
|
|
|
420
|
|
|
421 modem_echo_can_free(ctx);
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|
|
422 signal_free(&local_css);
|
|
|
423
|
|
|
424 if (afCloseFile(resulthandle) != 0)
|
|
|
425 {
|
|
|
426 fprintf(stderr, " Cannot close speech file '%s'\n", "result_sound.wav");
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|
|
427 exit(2);
|
|
|
428 }
|
|
|
429 afFreeFileSetup(filesetup);
|
|
|
430
|
|
|
431 #if defined(ENABLE_GUI)
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|
|
432 if (use_gui)
|
|
|
433 echo_can_monitor_wait_to_end();
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|
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434 #endif
|
|
|
435
|
|
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436 printf("Tests passed.\n");
|
|
|
437 return 0;
|
|
|
438 }
|
|
|
439 /*- End of function --------------------------------------------------------*/
|
|
|
440 /*- End of file ------------------------------------------------------------*/
|
