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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_connect_tones.c - Generation and detection of tones
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5 * associated with modems calling and answering calls.
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6 *
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7 * Written by Steve Underwood <steveu@coppice.org>
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8 *
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9 * Copyright (C) 2006 Steve Underwood
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10 *
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11 * All rights reserved.
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12 *
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13 * This program is free software; you can redistribute it and/or modify
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14 * it under the terms of the GNU General Public License version 2, as
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15 * published by the Free Software Foundation.
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16 *
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17 * This program is distributed in the hope that it will be useful,
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18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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20 * GNU General Public License for more details.
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21 *
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22 * You should have received a copy of the GNU General Public License
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23 * along with this program; if not, write to the Free Software
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24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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25 *
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26 * $Id: modem_connect_tones.c,v 1.6 2006/11/30 15:41:47 steveu Exp $
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27 */
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28
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29 /*! \file */
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30
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31 #ifdef HAVE_CONFIG_H
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32 #include <config.h>
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33 #endif
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34
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35 #include <inttypes.h>
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36 #include <stdlib.h>
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37 #if defined(HAVE_TGMATH_H)
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38 #include <tgmath.h>
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39 #endif
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40 #if defined(HAVE_MATH_H)
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41 #include <math.h>
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42 #endif
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43
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44 #include "spandsp/telephony.h"
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45 #include "spandsp/dds.h"
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46 #include "spandsp/tone_detect.h"
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47 #include "spandsp/tone_generate.h"
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48 #include "spandsp/super_tone_rx.h"
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49 #include "spandsp/modem_connect_tones.h"
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50
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51 int modem_connect_tones_tx(modem_connect_tones_tx_state_t *s,
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52 int16_t amp[],
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53 int len)
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54 {
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55 int mod;
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56 int i;
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57
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58 switch (s->tone_type)
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59 {
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60 case MODEM_CONNECT_TONES_FAX_CNG:
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61 case MODEM_CONNECT_TONES_FAX_CED:
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62 len = tone_gen(&s->tone_tx, amp, len);
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63 break;
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64 case MODEM_CONNECT_TONES_EC_DISABLE:
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65 for (i = 0; i < len; i++)
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66 {
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67 if (--s->hop_timer <= 0)
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68 {
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69 s->hop_timer = ms_to_samples(450);
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70 s->tone_phase += 0x80000000;
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71 }
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72 amp[i] = dds_mod(&s->tone_phase, s->tone_phase_rate, s->level, 0);
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73 }
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74 break;
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75 case MODEM_CONNECT_TONES_EC_DISABLE_MOD:
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76 for (i = 0; i < len; i++)
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77 {
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78 mod = s->level + dds_mod(&s->mod_phase, s->mod_phase_rate, s->mod_level, 0);
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79 if (--s->hop_timer <= 0)
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80 {
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81 s->hop_timer = ms_to_samples(450);
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82 s->tone_phase += 0x80000000;
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83 }
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84 amp[i] = dds_mod(&s->tone_phase, s->tone_phase_rate, mod, 0);
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85 }
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86 break;
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87 }
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88 return len;
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89 }
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90 /*- End of function --------------------------------------------------------*/
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91
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92 modem_connect_tones_tx_state_t *modem_connect_tones_tx_init(modem_connect_tones_tx_state_t *s,
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93 int tone_type)
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94 {
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95 tone_gen_descriptor_t tone_desc;
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96
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97 s->tone_type = tone_type;
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98 switch (s->tone_type)
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99 {
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100 case MODEM_CONNECT_TONES_FAX_CNG:
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101 make_tone_gen_descriptor(&tone_desc,
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102 1100,
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103 -11,
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104 0,
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105 0,
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106 500,
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107 3000,
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108 0,
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109 0,
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110 TRUE);
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111 tone_gen_init(&s->tone_tx, &tone_desc);
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112 break;
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113 case MODEM_CONNECT_TONES_FAX_CED:
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114 make_tone_gen_descriptor(&tone_desc,
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115 2100,
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116 -11,
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117 0,
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118 0,
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119 2600,
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120 0,
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121 0,
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122 0,
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123 FALSE);
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124 tone_gen_init(&s->tone_tx, &tone_desc);
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125 break;
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126 case MODEM_CONNECT_TONES_EC_DISABLE:
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127 case MODEM_CONNECT_TONES_EC_DISABLE_MOD:
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128 s->tone_phase_rate = dds_phase_rate(2100.0);
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129 s->mod_phase_rate = dds_phase_rate(15.0);
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130 s->tone_phase = 0;
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131 s->mod_phase = 0;
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132 s->hop_timer = ms_to_samples(450);
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133 s->level = dds_scaling_dbm0(-12);
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134 if (s->tone_type == MODEM_CONNECT_TONES_EC_DISABLE_MOD)
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135 s->mod_level = s->level/5;
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136 else
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137 s->mod_level = 0;
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138 }
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139 return s;
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140 }
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141 /*- End of function --------------------------------------------------------*/
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142
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143 int modem_connect_tones_rx(modem_connect_tones_rx_state_t *s, const int16_t amp[], int len)
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144 {
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145 int i;
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146 int16_t notched;
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147 float v1;
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148 float famp;
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149
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150 switch (s->tone_type)
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151 {
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152 case MODEM_CONNECT_TONES_FAX_CNG:
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153 for (i = 0; i < len; i++)
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154 {
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155 /* A Cauer notch at 1100Hz, spread just wide enough to meet our detection bandwidth
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156 criteria. */
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157 famp = amp[i];
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158 v1 = 0.792928f*famp + 1.0018744927985f*s->z1 - 0.54196833412465f*s->z2;
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159 famp = v1 - 1.2994747954630f*s->z1 + s->z2;
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160 s->z2 = s->z1;
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161 s->z1 = v1;
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162 notched = rintf(famp);
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163
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164 /* Estimate the overall energy in the channel, and the energy in
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165 the notch (i.e. overall channel energy - tone energy => noise).
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166 Use abs instead of multiply for speed (is it really faster?). */
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167 s->channel_level += ((abs(amp[i]) - s->channel_level) >> 5);
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168 s->notch_level += ((abs(notched) - s->notch_level) >> 5);
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169 if (s->channel_level > 70 && s->notch_level*6 < s->channel_level)
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170 {
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171 /* There is adequate energy in the channel, and it is mostly at 1100Hz. */
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172 if (!s->tone_present)
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173 {
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174 if (++s->tone_cycle_duration >= ms_to_samples(415))
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175 {
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176 if (s->tone_callback)
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177 s->tone_callback(s->callback_data, TRUE);
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178 else
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179 s->hit = TRUE;
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180 s->tone_present = TRUE;
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181 }
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182 }
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183 }
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184 else
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185 {
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186 s->tone_cycle_duration = 0;
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187 }
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188 }
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189 break;
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190 case MODEM_CONNECT_TONES_FAX_CED:
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191 for (i = 0; i < len; i++)
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192 {
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193 /* A Cauer notch at 2100Hz, spread just wide enough to meet our detection bandwidth
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194 criteria. */
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195 famp = amp[i];
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196 v1 = 0.76000f*famp - 0.1183852f*s->z1 - 0.5104039f*s->z2;
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197 famp = v1 + 0.1567596f*s->z1 + s->z2;
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198 s->z2 = s->z1;
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199 s->z1 = v1;
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200 notched = rintf(famp);
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201 /* Estimate the overall energy in the channel, and the energy in
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202 the notch (i.e. overall channel energy - tone energy => noise).
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203 Use abs instead of multiply for speed (is it really faster?). */
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204 s->channel_level += ((abs(amp[i]) - s->channel_level) >> 5);
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205 s->notch_level += ((abs(notched) - s->notch_level) >> 5);
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206 if (s->channel_level > 70 && s->notch_level*6 < s->channel_level)
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207 {
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208 /* There is adequate energy in the channel, and it is mostly at 2100Hz. */
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209 if (!s->tone_present)
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210 {
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211 if (++s->tone_cycle_duration >= ms_to_samples(500))
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212 {
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213 if (s->tone_callback)
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214 s->tone_callback(s->callback_data, TRUE);
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215 else
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216 s->hit = TRUE;
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217 s->tone_present = TRUE;
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218 }
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219 }
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220 }
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221 else
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222 {
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223 s->tone_cycle_duration = 0;
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224 }
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225 }
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226 break;
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227 case MODEM_CONNECT_TONES_EC_DISABLE:
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228 case MODEM_CONNECT_TONES_EC_DISABLE_MOD:
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229 for (i = 0; i < len; i++)
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230 {
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231 /* A Cauer notch at 2100Hz, spread just wide enough to meet our detection bandwidth
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232 criteria. */
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233 /* This is actually centred at 2095Hz, but gets the balance we want, due
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234 to the asymmetric walls of the notch */
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235 famp = amp[i];
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236 v1 = 0.76000f*famp - 0.1183852f*s->z1 - 0.5104039f*s->z2;
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237 famp = v1 + 0.1567596f*s->z1 + s->z2;
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238 s->z2 = s->z1;
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239 s->z1 = v1;
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240 notched = rintf(famp);
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241 /* Estimate the overall energy in the channel, and the energy in
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242 the notch (i.e. overall channel energy - tone energy => noise).
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243 Use abs instead of multiply for speed (is it really faster?).
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244 Damp the overall energy a little more for a stable result.
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245 Damp the notch energy a little less, so we don't damp out the
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246 blip every time the phase reverses */
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247 s->channel_level += ((abs(amp[i]) - s->channel_level) >> 5);
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248 s->notch_level += ((abs(notched) - s->notch_level) >> 4);
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249 if (s->channel_level > 280)
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250 {
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251 /* There is adequate energy in the channel. Is it mostly at 2100Hz? */
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252 if (s->notch_level*6 < s->channel_level)
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253 {
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254 /* The notch says yes, so we have the tone. */
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255 if (!s->tone_present)
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256 {
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257 /* Do we get a kick every 450+-25ms? */
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258 if (s->tone_cycle_duration >= ms_to_samples(425)
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259 &&
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260 s->tone_cycle_duration <= ms_to_samples(475))
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261 {
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262 if (++s->good_cycles > 2)
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263 {
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264 if (s->tone_callback)
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265 s->tone_callback(s->callback_data, TRUE);
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266 else
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267 s->hit = TRUE;
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268 }
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269 }
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270 s->tone_cycle_duration = 0;
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271 s->tone_present = TRUE;
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272 }
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273 }
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274 else
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275 {
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276 s->tone_present = FALSE;
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277 }
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278 s->tone_cycle_duration++;
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279 }
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280 else
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281 {
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282 s->tone_present = FALSE;
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283 s->tone_cycle_duration = 0;
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284 s->good_cycles = 0;
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285 }
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286 }
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287 }
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288 return 0;
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289 }
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290 /*- End of function --------------------------------------------------------*/
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291
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292 int modem_connect_tones_rx_get(modem_connect_tones_rx_state_t *s)
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293 {
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294 int x;
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295
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296 x = s->hit;
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297 s->hit = FALSE;
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298 return x;
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299 }
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300 /*- End of function --------------------------------------------------------*/
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301
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302 modem_connect_tones_rx_state_t *modem_connect_tones_rx_init(modem_connect_tones_rx_state_t *s,
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303 int tone_type,
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304 tone_report_func_t tone_callback,
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305 void *user_data)
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306 {
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307 s->tone_type = tone_type;
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308 s->channel_level = 0;
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309 s->notch_level = 0;
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310 s->tone_present = FALSE;
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311 s->tone_cycle_duration = 0;
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312 s->good_cycles = 0;
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313 s->hit = FALSE;
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314 s->tone_callback = tone_callback;
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315 s->callback_data = user_data;
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316 s->z1 = 0.0f;
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317 s->z2 = 0.0f;
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318 return s;
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319 }
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320 /*- End of function --------------------------------------------------------*/
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321 /*- End of file ------------------------------------------------------------*/
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