williamp/osmocom-analog
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

B-Netz: Use standard deviation to determine if an FSK frame is valid or not

Browse Source
This commit is contained in:
Andreas Eversberg
2017-08-13 14:15:53 +02:00
parent 41bd9999b1
commit ee61c4362b
3 changed files with 22 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
src/bnetz/dsp.c
View File

@@ -161,6 +161,7 @@ static void fsk_receive_tone(bnetz_t *bnetz, int bit, int goodtone, double level
/* Collect 16 data bits (digit) and check for sync mark '01110'. */
static void fsk_receive_bit(void *inst, int bit, double quality, double level)
{
double level_avg, level_dev, quality_avg;
bnetz_t *bnetz = (bnetz_t *)inst;
int i;
@@ -187,15 +188,24 @@ static void fsk_receive_bit(void *inst, int bit, double quality, double level)
return;
/* average level and quality */
level = quality = 0;
level_avg = level_dev = quality_avg = 0;
for (i = 0; i < 16; i++) {
level += bnetz->rx_telegramm_level[i];
quality += bnetz->rx_telegramm_quality[i];
level_avg += bnetz->rx_telegramm_level[bnetz->rx_telegramm_qualidx];
quality_avg += bnetz->rx_telegramm_quality[bnetz->rx_telegramm_qualidx];
if (++bnetz->rx_telegramm_qualidx == 16)
bnetz->rx_telegramm_qualidx = 0;
}
level /= 16.0; quality /= 16.0;
level_avg /= 16.0; quality_avg /= 16.0;
for (i = 0; i < 16; i++) {
level = bnetz->rx_telegramm_level[bnetz->rx_telegramm_qualidx];
level_dev += (level - level_avg) * (level - level_avg);
if (++bnetz->rx_telegramm_qualidx == 16)
bnetz->rx_telegramm_qualidx = 0;
}
level_dev = sqrt(level_dev / 16.0);
/* send telegramm */
bnetz_receive_telegramm(bnetz, bnetz->rx_telegramm, level, quality);
bnetz_receive_telegramm(bnetz, bnetz->rx_telegramm, level_avg, level_dev, quality_avg);
}
/* Process received audio stream from radio unit. */