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osmo-cc-ss5-endpoint
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Detect signaling tones before trying to detect MF tones. 

This prevents missing signaling tones, if MF tones or noise is present.
This commit is contained in:
Andreas Eversberg 2023-12-09 20:04:10 +01:00
parent 2c02ad31c0
commit 480179541f
1 changed files with 34 additions and 4 deletions
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38
src/common/dsp.c
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@ -35,6 +35,7 @@
//#define DEBUG_DEMODULATOR
#define NUM_TONES 8
#define NUM_MF_TONES 6
#define db2level(db) pow(10, (double)(db) / 20.0)
#define level2db(level) (20 * log10(level))
@ -416,19 +417,19 @@ static void detect_tones(dsp_t *dsp, sample_t *samples, sample_t **levels_square
}
#endif
/* find the tone which is the loudest */
/* find the signaling tone which is the loudest */
f1 = -1;
f1_level_squared = -1.0;
for (t = 0; t < dsp->mf_demod->tones; t++) {
for (t = NUM_MF_TONES; t < dsp->mf_demod->tones; t++) {
if (levels_squared[t][s] > f1_level_squared) {
f1_level_squared = levels_squared[t][s];
f1 = t;
}
}
/* find the tone which is the second loudest */
/* find the signaling tone which is the second loudest */
f2 = -1;
f2_level_squared = -1.0;
for (t = 0; t < dsp->mf_demod->tones; t++) {
for (t = NUM_MF_TONES; t < dsp->mf_demod->tones; t++) {
if (t == f1)
continue;
if (levels_squared[t][s] > f2_level_squared) {
@ -442,6 +443,35 @@ static void detect_tones(dsp_t *dsp, sample_t *samples, sample_t **levels_square
if (f2 >= 0 && f2_level_squared < tone_min_ampl_sq[f2])
f2 = -1;
/* if no signaling tone was found, check MF tones */
if (f1 < 0) {
/* find the MF tone which is the loudest */
f1 = -1;
f1_level_squared = -1.0;
for (t = 0; t < NUM_MF_TONES; t++) {
if (levels_squared[t][s] > f1_level_squared) {
f1_level_squared = levels_squared[t][s];
f1 = t;
}
}
/* find the MF tone which is the second loudest */
f2 = -1;
f2_level_squared = -1.0;
for (t = 0; t < NUM_MF_TONES; t++) {
if (t == f1)
continue;
if (levels_squared[t][s] > f2_level_squared) {
f2_level_squared = levels_squared[t][s];
f2 = t;
}
}
/* now check if the minimum level is reached */
if (f1 >= 0 && f1_level_squared < tone_min_ampl_sq[f1])
f1 = -1;
if (f2 >= 0 && f2_level_squared < tone_min_ampl_sq[f2])
f2 = -1;
}
#ifdef DEBUG_DEMODULATOR
if (incoming)
printf("%s f1=%.0f (%.1f dBm) f2=%.0f (%.1f dBm)\n", CHAN, (f1 >= 0) ? tone_freq[f1] : 0, level2db(sqrt(f1_level_squared)), (f2 >= 0) ? tone_freq[f2] : 0, level2db(sqrt(f2_level_squared)));