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Add parameter to DTMF decode to change frequency margin 

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This commit is contained in:
Andreas Eversberg 2024-04-21 14:47:06 +02:00
parent 49925d4b95
commit b16b26d326
4 changed files with 10 additions and 7 deletions
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2
src/jolly/dsp.c
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@ -90,7 +90,7 @@ int dsp_init_sender(jolly_t *jolly, int nbfm, double squelch_db, int repeater)
/* init dtmf audio processing.
* each frequency may be +6 dB deviation, which means a total deviation of +12 dB is allowed for detection.
* also we allow a minimum of -30 dB for each tone. */
rc = dtmf_decode_init(&jolly->dtmf, jolly, jolly_receive_dtmf, 8000, db2level(6.0), db2level(-30.0));
rc = dtmf_decode_init(&jolly->dtmf, jolly, jolly_receive_dtmf, 8000, db2level(6.0), db2level(-30.0), DTMF_FREQ_MARGIN_PERCENT_DEFAULT);
if (rc < 0) {
LOGP(DDSP, LOGL_ERROR, "Failed to init DTMF decoder!\n");
goto error;

6
src/libdtmf/dtmf_decode.c
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@ -41,7 +41,7 @@
static const char dtmf_digit[] = " 123A456B789C*0#D";
int dtmf_decode_init(dtmf_dec_t *dtmf, void *priv, void (*recv_digit)(void *priv, char digit, dtmf_meas_t *meas), int samplerate, double max_amplitude, double min_amplitude)
int dtmf_decode_init(dtmf_dec_t *dtmf, void *priv, void (*recv_digit)(void *priv, char digit, dtmf_meas_t *meas), int samplerate, double max_amplitude, double min_amplitude, double freq_margin)
{
int rc;
@ -49,7 +49,7 @@ int dtmf_decode_init(dtmf_dec_t *dtmf, void *priv, void (*recv_digit)(void *priv
dtmf->priv = priv;
dtmf->recv_digit = recv_digit;
dtmf->samplerate = samplerate;
dtmf->freq_margin = 1.03; /* 1.8 .. 3.5 % */
dtmf->freq_margin = freq_margin;
dtmf->max_amplitude = max_amplitude;
dtmf->min_amplitude = min_amplitude;
dtmf->forward_twist = db2level(4.0);
@ -118,7 +118,7 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
int amplitude_ok, twist_ok;
int i;
margin = dtmf->freq_margin;
margin = dtmf->freq_margin / 100.0 + 1.0;
min_amplitude = dtmf->min_amplitude;
max_amplitude = dtmf->max_amplitude;
forward_twist = dtmf->forward_twist;

6
src/libdtmf/dtmf_decode.h
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@ -1,6 +1,8 @@
#include "../libfm/fm.h"
typedef struct ftmf_meas {
#define DTMF_FREQ_MARGIN_PERCENT_DEFAULT 3 /* 1.8 .. 3.5 % */
typedef struct dtmf_meas {
double frequency_low;
double frequency_high;
double amplitude_low;
@ -28,7 +30,7 @@ typedef struct dtmf_dec {
dtmf_meas_t meas; /* measurements */
} dtmf_dec_t;
int dtmf_decode_init(dtmf_dec_t *dtmf, void *priv, void (*recv_digit)(void *priv, char digit, dtmf_meas_t *meas), int samplerate, double max_amplitude, double min_amplitude);
int dtmf_decode_init(dtmf_dec_t *dtmf, void *priv, void (*recv_digit)(void *priv, char digit, dtmf_meas_t *meas), int samplerate, double max_amplitude, double min_amplitude, double freq_margin);
void dtmf_decode_exit(dtmf_dec_t *dtmf);
void dtmf_decode_reset(dtmf_dec_t *dtmf);
void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length);

3
src/test/test_dtmf.c
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@ -65,7 +65,8 @@ int main(void)
fm_init(0);
dtmf_decode_init(&dtmf_dec, NULL, recv_digit, SAMPLERATE, db2level(0), db2level(-30.0));
/* decoder uses a strict frequency offset of 0.1 percent. */
dtmf_decode_init(&dtmf_dec, NULL, recv_digit, SAMPLERATE, db2level(0), db2level(-30.0), 0.1);
for (f = 0; f < 8; f++) {
printf("Testing filter with frequency %.0f Hz:\n", test_frequency[f]);