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authorAndreas Eversberg <jolly@eversberg.eu>2020-10-11 18:03:12 +0200
committerAndreas Eversberg <jolly@eversberg.eu>2020-10-29 08:01:37 +0100
commitf37dfbe4ee5c1e33957bb9c3d9e4b47c8d0c5662 (patch)
treeb984a3c40b75e288d6d538404921d6968238b34e
parent51204b55a990662c33d7b5190f587a2f11920550 (diff)
DTMF: Correctly handle frequency marging (percent not hertz!)
-rw-r--r--src/libdtmf/dtmf_decode.c38
-rw-r--r--src/libdtmf/dtmf_decode.h2
2 files changed, 20 insertions, 20 deletions
diff --git a/src/libdtmf/dtmf_decode.c b/src/libdtmf/dtmf_decode.c
index c9ace1e..740d504 100644
--- a/src/libdtmf/dtmf_decode.c
+++ b/src/libdtmf/dtmf_decode.c
@@ -64,7 +64,7 @@ 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_tollerance = 3.0;
+ dtmf->freq_margin = 1.03; /* 1.8 .. 3.5 % */
dtmf->max_amplitude = max_amplitude;
dtmf->min_amplitude = min_amplitude;
dtmf->forward_twist = db2level(4.0);
@@ -119,15 +119,15 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
{
sample_t frequency_low[length], amplitude_low[length];
sample_t frequency_high[length], amplitude_high[length];
- double tollerance, min_amplitude, max_amplitude, forward_twist, reverse_twist, f1, f2;
+ double margin, min_amplitude, max_amplitude, forward_twist, reverse_twist, f1, f2;
int time_detect, time_meas, time_pause;
int low = 0, high = 0;
char detected, digit;
int count;
- int aplitude_ok, twist_ok;
+ int amplitude_ok, twist_ok;
int i;
- tollerance = dtmf->freq_tollerance;
+ margin = dtmf->freq_margin;
min_amplitude = dtmf->min_amplitude;
max_amplitude = dtmf->max_amplitude;
forward_twist = dtmf->forward_twist;
@@ -143,27 +143,27 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
for (i = 0; i < length; i++) {
#ifdef DEBUG
- printf("%s %.5f\n", _debug_amplitude(samples[i]/2.0), samples[i]/2.0);
+// printf("%s %.5f\n", _debug_amplitude(samples[i]/2.0), samples[i]/2.0);
#endif
/* get frequency of low frequencies, correct amplitude drop at cutoff point */
f1 = frequency_low[i] + (DTMF_LOW_1 + DTMF_LOW_4) / 2.0;
- if (f1 >= DTMF_LOW_1 - tollerance && f1 <= DTMF_LOW_1 + tollerance) {
+ if (f1 >= DTMF_LOW_1 / margin && f1 <= DTMF_LOW_1 * margin) {
/* cutoff point */
amplitude_low[i] /= 0.7071;
low = 1;
f1 -= DTMF_LOW_1;
} else
- if (f1 >= DTMF_LOW_2 - tollerance && f1 <= DTMF_LOW_2 + tollerance) {
+ if (f1 >= DTMF_LOW_2 / margin && f1 <= DTMF_LOW_2 * margin) {
amplitude_low[i] /= 1.0734;
low = 2;
f1 -= DTMF_LOW_2;
} else
- if (f1 >= DTMF_LOW_3 - tollerance && f1 <= DTMF_LOW_3 + tollerance) {
+ if (f1 >= DTMF_LOW_3 / margin && f1 <= DTMF_LOW_3 * margin) {
amplitude_low[i] /= 1.0389;
low = 3;
f1 -= DTMF_LOW_3;
} else
- if (f1 >= DTMF_LOW_4 - tollerance && f1 <= DTMF_LOW_4 + tollerance) {
+ if (f1 >= DTMF_LOW_4 / margin && f1 <= DTMF_LOW_4 * margin) {
/* cutoff point */
amplitude_low[i] /= 0.7071;
low = 4;
@@ -172,23 +172,23 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
low = 0;
/* get frequency of high frequencies, correct amplitude drop at cutoff point */
f2 = frequency_high[i] + (DTMF_HIGH_1 + DTMF_HIGH_4) / 2.0;
- if (f2 >= DTMF_HIGH_1 - tollerance && f2 <= DTMF_HIGH_1 + tollerance) {
+ if (f2 >= DTMF_HIGH_1 / margin && f2 <= DTMF_HIGH_1 * margin) {
/* cutoff point */
amplitude_high[i] /= 0.7071;
high = 1;
f2 -= DTMF_HIGH_1;
} else
- if (f2 >= DTMF_HIGH_2 - tollerance && f2 <= DTMF_HIGH_2 + tollerance) {
+ if (f2 >= DTMF_HIGH_2 / margin && f2 <= DTMF_HIGH_2 * margin) {
amplitude_high[i] /= 1.0731;
high = 2;
f2 -= DTMF_HIGH_2;
} else
- if (f2 >= DTMF_HIGH_3 - tollerance && f2 <= DTMF_HIGH_3 + tollerance) {
+ if (f2 >= DTMF_HIGH_3 / margin && f2 <= DTMF_HIGH_3 * margin) {
amplitude_high[i] /= 1.0372;
high = 3;
f2 -= DTMF_HIGH_3;
} else
- if (f2 >= DTMF_HIGH_4 - tollerance && f2 <= DTMF_HIGH_4 + tollerance) {
+ if (f2 >= DTMF_HIGH_4 / margin && f2 <= DTMF_HIGH_4 * margin) {
/* cutoff point */
amplitude_high[i] /= 0.7071;
high = 4;
@@ -196,15 +196,15 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
} else
high = 0;
digit = 0;
- aplitude_ok = 0;
+ amplitude_ok = 0;
twist_ok = 0;
if (low && high) {
digit = dtmf_digit[low*4+high];
/* check for limits */
if (amplitude_low[i] <= max_amplitude && amplitude_low[i] >= min_amplitude && amplitude_high[i] <= max_amplitude && amplitude_high[i] >= min_amplitude) {
- aplitude_ok = 1;
+ amplitude_ok = 1;
#ifdef DEBUG
- printf("%.5f %.5f %.1f\n", amplitude_low[i], amplitude_high[i], level2db(amplitude_high[i] / amplitude_low[i]));
+ printf("%.1f %.1f (limits %.1f .. %.1f) %.1f\n", level2db(amplitude_low[i]), level2db(amplitude_high[i]), level2db(min_amplitude), level2db(max_amplitude), level2db(amplitude_high[i] / amplitude_low[i]));
#endif
if (amplitude_high[i] / amplitude_low[i] <= forward_twist && amplitude_low[i] / amplitude_high[i] <= reverse_twist)
twist_ok = 1;
@@ -212,7 +212,7 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
}
if (!detected) {
- if (digit && aplitude_ok && twist_ok) {
+ if (digit && amplitude_ok && twist_ok) {
if (count == 0) {
memset(&dtmf->meas, 0, sizeof(dtmf->meas));
}
@@ -236,7 +236,7 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
} else
count = 0;
} else {
- if (!digit || digit != detected || !aplitude_ok || !twist_ok) {
+ if (!digit || digit != detected || !amplitude_ok || !twist_ok) {
count++;
if (count >= time_pause) {
detected = 0;
@@ -249,7 +249,7 @@ void dtmf_decode(dtmf_dec_t *dtmf, sample_t *samples, int length)
}
#ifdef DEBUG
if (digit)
- printf("DTMF tone='%c' diff frequency=%.1f %.1f amplitude=%.1f %.1f dB (%s) twist=%.1f dB (%s)\n", digit, f1, f2, level2db(amplitude_low[i]), level2db(amplitude_high[i]), (aplitude_ok) ? "OK" : "nok", level2db(amplitude_high[i] / amplitude_low[i]), (twist_ok) ? "OK" : "nok");
+ printf("DTMF tone='%c' diff frequency=%.1f %.1f amplitude=%.1f %.1f dB (%s) twist=%.1f dB (%s)\n", digit, f1, f2, level2db(amplitude_low[i]), level2db(amplitude_high[i]), (amplitude_ok) ? "OK" : "nok", level2db(amplitude_high[i] / amplitude_low[i]), (twist_ok) ? "OK" : "nok");
#endif
dtmf->detected = detected;
diff --git a/src/libdtmf/dtmf_decode.h b/src/libdtmf/dtmf_decode.h
index 4aa6546..7c5780f 100644
--- a/src/libdtmf/dtmf_decode.h
+++ b/src/libdtmf/dtmf_decode.h
@@ -12,7 +12,7 @@ typedef struct dtmf_dec {
void *priv;
void (*recv_digit)(void *priv, char digit, dtmf_meas_t *meas);
int samplerate; /* samplerate */
- double freq_tollerance; /* +- limit of frequency deviation to allow */
+ double freq_margin; /* +- limit of frequency deviation (percent) valid tone*/
double min_amplitude; /* minimum amplitude relative to 0 dBm */
double max_amplitude; /* maximum amplitude relative to 0 dBm */
double forward_twist; /* how much do higher frequencies are louder than lower frequencies */