static int16_t channel_model(int16_t *new_local, int16_t *new_far, int16_t local, int16_t far)
{
int16_t echo;
int16_t rx;
/* Channel modelling is merely simulating the effects of A-law or u-law distortion
and using one of the echo models from G.168. Simulating the codec is very important,
as this is usually the limiting factor in how much echo reduction is achieved. */
/* The local tx signal will usually have gone through an A-law munging before
it reached the line's analogue area, where the echo occurs. */
local = codec_munge(local);
/* Now we need to model the echo. We only model a single analogue segment, as per
the G.168 spec. However, there will generally be near end and far end analogue/echoey
segments in the real world, unless an end is purely digital. */
echo = fir32(&line_model, local/8);
/* The far end signal will have been through an A-law munging, although
this should not affect things. */
rx = echo + codec_munge(far);
/* This mixed echo and far end signal will have been through an A-law munging
when it came back into the digital network. */
rx = codec_munge(rx);
if (new_far)
*new_far = rx;
if (new_local)
*new_local = local;
return rx;
}
int main(int argc, char *argv[])
{
int f;
int i;
int16_t amp[8000];
int16_t value;
int signal;
float power[10];
tone_gen_descriptor_t tone_desc;
tone_gen_state_t tone_state;
awgn_state_t noise_source;
fir32_state_t line_model_d2;
fir32_state_t line_model_d3;
fir32_state_t line_model_d4;
fir32_state_t line_model_d5;
fir32_state_t line_model_d6;
fir32_state_t line_model_d7;
fir32_state_t line_model_d8;
fir32_state_t line_model_d9;
fir_float_state_t level_measurement_bp;
signal_load(&local_css, "sound_c1_8k.wav");
signal_load(&far_css, "sound_c3_8k.wav");
fir32_create(&line_model_d2,
line_model_d2_coeffs,
sizeof(line_model_d2_coeffs)/sizeof(int32_t));
fir32_create(&line_model_d3,
line_model_d3_coeffs,
sizeof(line_model_d3_coeffs)/sizeof(int32_t));
fir32_create(&line_model_d4,
line_model_d4_coeffs,
sizeof(line_model_d4_coeffs)/sizeof(int32_t));
fir32_create(&line_model_d5,
line_model_d5_coeffs,
sizeof(line_model_d5_coeffs)/sizeof(int32_t));
fir32_create(&line_model_d6,
line_model_d6_coeffs,
sizeof(line_model_d6_coeffs)/sizeof(int32_t));
fir32_create(&line_model_d7,
line_model_d7_coeffs,
sizeof(line_model_d7_coeffs)/sizeof(int32_t));
fir32_create(&line_model_d8,
line_model_d8_coeffs,
sizeof(line_model_d8_coeffs)/sizeof(int32_t));
fir32_create(&line_model_d9,
line_model_d9_coeffs,
sizeof(line_model_d9_coeffs)/sizeof(int32_t));
fir_float_create(&level_measurement_bp,
level_measurement_bp_coeffs,
sizeof(level_measurement_bp_coeffs)/sizeof(float));
for (f = 10; f < 4000; f++)
{
tone_gen_descriptor_init(&tone_desc,
f,
-10,
0,
0,
1,
0,
0,
0,
true);
tone_gen_init(&tone_state, &tone_desc);
tone_gen(&tone_state, amp, 8000);
for (i = 0; i < 10; i++)
power[i] = 0.0f;
for (i = 0; i < 800; i++)
{
signal = fir32(&line_model_d2, amp[i]);
power[0] += ((signal*signal - power[0])/32.0f);
signal = fir32(&line_model_d3, amp[i]);
power[1] += ((signal*signal - power[1])/32.0f);
signal = fir32(&line_model_d4, amp[i]);
power[2] += ((signal*signal - power[2])/32.0f);
signal = fir32(&line_model_d5, amp[i]);
power[3] += ((signal*signal - power[3])/32.0f);
signal = fir32(&line_model_d6, amp[i]);
power[4] += ((signal*signal - power[4])/32.0f);
signal = fir32(&line_model_d7, amp[i]);
power[5] += ((signal*signal - power[5])/32.0f);
signal = fir32(&line_model_d8, amp[i]);
power[6] += ((signal*signal - power[6])/32.0f);
signal = fir32(&line_model_d9, amp[i]);
power[7] += ((signal*signal - power[7])/32.0f);
signal = fir_float(&level_measurement_bp, amp[i]);
power[8] += ((signal*signal - power[8])/32.0f);
signal = amp[i];
power[9] += ((signal*signal - power[9])/32.0f);
}
printf("%d %f %f %f %f %f %f %f %f %f %f\n",
f,
sqrt(power[0])*LINE_MODEL_D2_GAIN,
sqrt(power[1])*LINE_MODEL_D3_GAIN,
sqrt(power[2])*LINE_MODEL_D4_GAIN,
sqrt(power[3])*LINE_MODEL_D5_GAIN,
sqrt(power[4])*LINE_MODEL_D6_GAIN,
sqrt(power[5])*LINE_MODEL_D7_GAIN,
sqrt(power[6])*LINE_MODEL_D8_GAIN,
sqrt(power[7])*LINE_MODEL_D9_GAIN,
sqrt(power[8]),
sqrt(power[9]));
}
awgn_init_dbm0(&noise_source, 1234567, -20.0f);
for (i = 0; i < 10; i++)
power[i] = 0.0f;
signal_restart(&local_css, 0.0f);
signal_restart(&far_css, 0.0f);
for (i = 0; i < SAMPLE_RATE; i++)
{
value = signal_amp(&local_css);
//value = awgn(&noise_source);
signal = fir32(&line_model_d2, value);
power[0] += ((signal*signal - power[0])/32.0f);
signal = fir32(&line_model_d3, value);
power[1] += ((signal*signal - power[1])/32.0f);
signal = fir32(&line_model_d4, value);
power[2] += ((signal*signal - power[2])/32.0f);
signal = fir32(&line_model_d5, value);
power[3] += ((signal*signal - power[3])/32.0f);
signal = fir32(&line_model_d6, value);
power[4] += ((signal*signal - power[4])/32.0f);
signal = fir32(&line_model_d7, value);
power[5] += ((signal*signal - power[5])/32.0f);
signal = fir32(&line_model_d8, value);
power[6] += ((signal*signal - power[6])/32.0f);
signal = fir32(&line_model_d9, value);
power[7] += ((signal*signal - power[7])/32.0f);
signal = fir_float(&level_measurement_bp, value);
power[8] += ((signal*signal - power[8])/32.0f);
signal = value;
power[9] += ((signal*signal - power[9])/32.0f);
}
for (i = 0; i < 10; i++)
power[i] = 0.0f;
for (i = 0; i < SAMPLE_RATE; i++)
{
value = signal_amp(&local_css);
//value = awgn(&noise_source);
signal = fir32(&line_model_d2, value);
power[0] += ((signal*signal - power[0])/32.0f);
signal = fir32(&line_model_d3, value);
power[1] += ((signal*signal - power[1])/32.0f);
signal = fir32(&line_model_d4, value);
power[2] += ((signal*signal - power[2])/32.0f);
signal = fir32(&line_model_d5, value);
power[3] += ((signal*signal - power[3])/32.0f);
signal = fir32(&line_model_d6, value);
power[4] += ((signal*signal - power[4])/32.0f);
signal = fir32(&line_model_d7, value);
power[5] += ((signal*signal - power[5])/32.0f);
signal = fir32(&line_model_d8, value);
power[6] += ((signal*signal - power[6])/32.0f);
signal = fir32(&line_model_d9, value);
power[7] += ((signal*signal - power[7])/32.0f);
signal = fir_float(&level_measurement_bp, value);
power[8] += ((signal*signal - power[8])/32.0f);
signal = value;
power[9] += ((signal*signal - power[9])/32.0f);
}
printf("%d %f %f %f %f %f %f %f %f %f %f\n",
0,
sqrt(power[0])*LINE_MODEL_D2_GAIN,
sqrt(power[1])*LINE_MODEL_D3_GAIN,
sqrt(power[2])*LINE_MODEL_D4_GAIN,
sqrt(power[3])*LINE_MODEL_D5_GAIN,
sqrt(power[4])*LINE_MODEL_D6_GAIN,
sqrt(power[5])*LINE_MODEL_D7_GAIN,
sqrt(power[6])*LINE_MODEL_D8_GAIN,
sqrt(power[7])*LINE_MODEL_D9_GAIN,
sqrt(power[8]),
sqrt(power[9]));
printf("%d %f %f %f %f %f %f %f %f %f %f\n",
0,
sqrt(power[0]),
sqrt(power[1]),
sqrt(power[2]),
sqrt(power[3]),
sqrt(power[4]),
sqrt(power[5]),
sqrt(power[6]),
sqrt(power[7]),
sqrt(power[8]),
sqrt(power[9]));
printf("%d %f %f %f %f %f %f %f %f %f %f\n",
0,
sqrt(power[0])/sqrt(power[9]),
sqrt(power[1])/sqrt(power[9]),
sqrt(power[2])/sqrt(power[9]),
sqrt(power[3])/sqrt(power[9]),
sqrt(power[4])/sqrt(power[9]),
sqrt(power[5])/sqrt(power[9]),
sqrt(power[6])/sqrt(power[9]),
sqrt(power[7])/sqrt(power[9]),
sqrt(power[8]),
sqrt(power[9]));
printf("%d %f %f %f %f %f %f %f %f %f %f\n",
0,
sqrt(power[0])*LINE_MODEL_D2_GAIN/sqrt(power[9]),
sqrt(power[1])*LINE_MODEL_D3_GAIN/sqrt(power[9]),
sqrt(power[2])*LINE_MODEL_D4_GAIN/sqrt(power[9]),
sqrt(power[3])*LINE_MODEL_D5_GAIN/sqrt(power[9]),
sqrt(power[4])*LINE_MODEL_D6_GAIN/sqrt(power[9]),
sqrt(power[5])*LINE_MODEL_D7_GAIN/sqrt(power[9]),
sqrt(power[6])*LINE_MODEL_D8_GAIN/sqrt(power[9]),
sqrt(power[7])*LINE_MODEL_D9_GAIN/sqrt(power[9]),
sqrt(power[8]),
sqrt(power[9]));
for (i = 0; i < (int) (sizeof(css_c1)/sizeof(css_c1[0])); i++)
printf("%d\n", css_c1[i]);
printf("\n");
for (i = 0; i < (int) (sizeof(css_c1)/sizeof(css_c3[0])); i++)
printf("%d\n", css_c3[i]);
signal_free(&local_css);
signal_free(&far_css);
fir32_free(&line_model_d2);
fir32_free(&line_model_d3);
fir32_free(&line_model_d4);
fir32_free(&line_model_d5);
fir32_free(&line_model_d6);
fir32_free(&line_model_d7);
fir32_free(&line_model_d8);
fir32_free(&line_model_d9);
fir_float_free(&level_measurement_bp);
return 0;
}
