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C-Netz: Show standard deviation of bit levels instead of jitter

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This commit is contained in:
Andreas Eversberg
2017-10-02 12:28:51 +02:00
parent 5ea48588e5
commit 3f2f0fdd8c
4 changed files with 31 additions and 19 deletions
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38
src/cnetz/fsk_demod.c
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@@ -218,12 +218,12 @@ void fsk_fm_exit(fsk_fm_demod_t *fsk)
#endif
}
/* get levels, sync time and jitter from sync sequence or frame data */
static inline void get_levels(fsk_fm_demod_t *fsk, double *_min, double *_max, double *_avg, int *_probes, int num, double *_time, double *_jitter)
/* get levels, sync time and jitter/stddev from sync sequence or frame data */
static inline void get_levels(fsk_fm_demod_t *fsk, double *_min, double *_max, double *_avg, int *_probes, int num, double *_time, double *_jitter, double *_stddev)
{
int count = 0;
double min = 0, max = 0, avg = 0, level;
double time = 0, t, sync_average, sync_time, jitter = 0;
double time = 0, t, sync_average, sync_time, jitter = 0.0, stddev = 0.0;
int bit_offset;
int i;
@@ -252,6 +252,8 @@ static inline void get_levels(fsk_fm_demod_t *fsk, double *_min, double *_max, d
avg += level;
count++;
}
avg /= (double)count;
time /= (double)count;
/* should never happen */
if (!count) {
@@ -264,13 +266,13 @@ static inline void get_levels(fsk_fm_demod_t *fsk, double *_min, double *_max, d
* late (positive) we received the sync relative to current bit_time.
* sync_time is the absolute time within the super frame.
*/
sync_average = time / (double)count;
sync_average = time;
sync_time = fmod(sync_average + fsk->bit_time + BITS_PER_SUPERFRAME, BITS_PER_SUPERFRAME);
*_probes = count;
*_min = min;
*_max = max;
*_avg = avg / (double)count;
*_avg = avg;
if (_time) {
// if (fsk->cnetz->dsp_mode == DSP_MODE_SPK_V)
@@ -303,6 +305,16 @@ static inline void get_levels(fsk_fm_demod_t *fsk, double *_min, double *_max, d
}
*_jitter = jitter / (double)count;
}
if (_stddev) {
/* get standard deviation of level */
for (i = 0; i < num; i++) {
level = fsk->change_levels[(fsk->change_pos - 1 - i) & 0xff];
if (level <= 0.0)
continue;
stddev += (level - avg) * (level - avg);
}
*_stddev = sqrt(stddev / (double)count);
}
}
static inline void got_bit(fsk_fm_demod_t *fsk, int bit, double change_level)
@@ -348,11 +360,11 @@ got_sync:
if (debug)
fprintf(fsk->debug_fp, " SYNC!");
#endif
get_levels(fsk, &min, &max, &avg, &probes, 30, &fsk->sync_time, &fsk->sync_jitter);
get_levels(fsk, &min, &max, &avg, &probes, 30, &fsk->sync_time, NULL, &fsk->sync_stddev);
fsk->sync_level = avg;
if (fsk->sync == FSK_SYNC_NEGATIVE)
fsk->sync_level = -fsk->sync_level;
// printf("sync (change min=%.0f%% max=%.0f%% avg=%.0f%% sync_time=%.2f jitter=%.2f probes=%d)\n", min * 100, max * 100, avg * 100, fsk->sync_time, fsk->sync_jitter, probes);
// printf("sync (change min=%.0f%% max=%.0f%% avg=%.0f%% sync_time=%.2f stddev=%.0f%% probes=%d)\n", min * 100, max * 100, avg * 100, fsk->sync_time, fsk->sync_stddev / avg, probes);
fsk->level_threshold = (double)avg;
fsk->rx_sync = 0;
fsk->rx_buffer_count = 0;
@@ -381,7 +393,8 @@ got_sync:
/* received 662 bits after start of block (10 SPK blocks + 1 bit (== 2 level changes)) */
fsk->sync_time = fmod(fsk->sync_time - (66*10+2) + BITS_PER_SUPERFRAME, BITS_PER_SUPERFRAME);
}
cnetz_decode_telegramm(fsk->cnetz, fsk->rx_buffer, fsk->sync_level, fsk->sync_time, fsk->sync_jitter);
/* receive frame */
cnetz_decode_telegramm(fsk->cnetz, fsk->rx_buffer, fsk->sync_level, fsk->sync_time, fsk->sync_stddev);
}
break;
}
@@ -457,7 +470,7 @@ static inline void find_change_slope(fsk_fm_demod_t *fsk)
fsk->last_change_positive = change_positive;
if (!fsk->sync) {
fsk->next_bit = 1.5;
got_bit(fsk, change_positive, (level_max - level_min) / 2);
got_bit(fsk, change_positive, (level_max - level_min) / 2.0);
}
}
if (fsk->next_bit <= 0.0) {
@@ -530,9 +543,10 @@ static inline void find_change_level(fsk_fm_demod_t *fsk)
fsk->last_change_positive = change_positive;
if (!fsk->sync) {
fsk->next_bit = 1.5;
/* if bit change is inside window, we can get level from end of window */
s = fsk->bit_buffer_spl[(fsk->bit_buffer_pos + fsk->bit_buffer_len - 1) % fsk->bit_buffer_len];
got_bit(fsk, change_positive, fabs(s));
/* if bit change is inside window, we can get level from borders of window */
s = fsk->bit_buffer_spl[fsk->bit_buffer_pos];
s -= fsk->bit_buffer_spl[(fsk->bit_buffer_pos + fsk->bit_buffer_len - 1) % fsk->bit_buffer_len];
got_bit(fsk, change_positive, fabs(s / 2.0));
}
}
if (fsk->next_bit <= 0.0) {