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

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
View File

@ -218,12 +218,12 @@ void fsk_fm_exit(fsk_fm_demod_t *fsk)
#endif #endif
} }
/* get levels, sync time and jitter from sync sequence or frame data */ /* 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) 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; int count = 0;
double min = 0, max = 0, avg = 0, level; 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 bit_offset;
int i; int i;
@ -252,6 +252,8 @@ static inline void get_levels(fsk_fm_demod_t *fsk, double *_min, double *_max, d
avg += level; avg += level;
count++; count++;
} }
avg /= (double)count;
time /= (double)count;
/* should never happen */ /* should never happen */
if (!count) { 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. * late (positive) we received the sync relative to current bit_time.
* sync_time is the absolute time within the super frame. * 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); sync_time = fmod(sync_average + fsk->bit_time + BITS_PER_SUPERFRAME, BITS_PER_SUPERFRAME);
*_probes = count; *_probes = count;
*_min = min; *_min = min;
*_max = max; *_max = max;
*_avg = avg / (double)count; *_avg = avg;
if (_time) { if (_time) {
// if (fsk->cnetz->dsp_mode == DSP_MODE_SPK_V) // 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; *_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) static inline void got_bit(fsk_fm_demod_t *fsk, int bit, double change_level)
@ -348,11 +360,11 @@ got_sync:
if (debug) if (debug)
fprintf(fsk->debug_fp, " SYNC!"); fprintf(fsk->debug_fp, " SYNC!");
#endif #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; fsk->sync_level = avg;
if (fsk->sync == FSK_SYNC_NEGATIVE) if (fsk->sync == FSK_SYNC_NEGATIVE)
fsk->sync_level = -fsk->sync_level; 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->level_threshold = (double)avg;
fsk->rx_sync = 0; fsk->rx_sync = 0;
fsk->rx_buffer_count = 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)) */ /* 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); 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; break;
} }
@ -457,7 +470,7 @@ static inline void find_change_slope(fsk_fm_demod_t *fsk)
fsk->last_change_positive = change_positive; fsk->last_change_positive = change_positive;
if (!fsk->sync) { if (!fsk->sync) {
fsk->next_bit = 1.5; 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) { 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; fsk->last_change_positive = change_positive;
if (!fsk->sync) { if (!fsk->sync) {
fsk->next_bit = 1.5; fsk->next_bit = 1.5;
/* if bit change is inside window, we can get level from end of window */ /* if bit change is inside window, we can get level from borders of window */
s = fsk->bit_buffer_spl[(fsk->bit_buffer_pos + fsk->bit_buffer_len - 1) % fsk->bit_buffer_len]; s = fsk->bit_buffer_spl[fsk->bit_buffer_pos];
got_bit(fsk, change_positive, fabs(s)); 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) { if (fsk->next_bit <= 0.0) {

2
src/cnetz/fsk_demod.h
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@ -39,7 +39,7 @@ typedef struct fsk_fm_demod {
enum fsk_sync sync; /* set, if we are in sync and what polarity we receive */ enum fsk_sync sync; /* set, if we are in sync and what polarity we receive */
double sync_level; /* what was the level, when we received the sync */ double sync_level; /* what was the level, when we received the sync */
double sync_time; /* when did we receive sync, relative to super frame */ double sync_time; /* when did we receive sync, relative to super frame */
double sync_jitter; /* what was the jitter of the sync */ double sync_stddev; /* standard deviation of level changes */
/* speech */ /* speech */
sample_t *speech_buffer; /* holds one chunk of 12.5ms */ sample_t *speech_buffer; /* holds one chunk of 12.5ms */

7
src/cnetz/telegramm.c
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@ -1462,7 +1462,7 @@ static const char *deinterleave(const char *input)
return output; return output;
} }
void cnetz_decode_telegramm(cnetz_t *cnetz, const char *bits, double level, double sync_time, double jitter) void cnetz_decode_telegramm(cnetz_t *cnetz, const char *bits, double level, double sync_time, double stddev)
{ {
telegramm_t telegramm; telegramm_t telegramm;
uint8_t opcode; uint8_t opcode;
@ -1489,12 +1489,11 @@ void cnetz_decode_telegramm(cnetz_t *cnetz, const char *bits, double level, doub
opcode = telegramm.opcode; opcode = telegramm.opcode;
telegramm.level = level; telegramm.level = level;
telegramm.sync_time = sync_time; telegramm.sync_time = sync_time;
telegramm.jitter = jitter;
if (bit_errors) if (bit_errors)
PDEBUG_CHAN(DDSP, DEBUG_INFO, "RX Level: %.0f%% Jitter: %.2f Sync Time: %.2f (TS %.2f) Bit errors: %d %s\n", fabs(level) / cnetz->fsk_deviation * 100.0, jitter, sync_time, sync_time / 396.0, bit_errors, (level < 0) ? "NEGATIVE (phone's mode)" : "POSITIVE (base station's mode)"); PDEBUG_CHAN(DDSP, DEBUG_INFO, "RX Level: %.0f%% Standard deviation: %.0f%% Sync Time: %.2f (TS %.2f) Bit errors: %d %s\n", fabs(level) / cnetz->fsk_deviation * 100.0, stddev / fabs(level) * 100.0, sync_time, sync_time / 396.0, bit_errors, (level < 0) ? "NEGATIVE (phone's mode)" : "POSITIVE (base station's mode)");
else else
PDEBUG_CHAN(DDSP, DEBUG_INFO, "RX Level: %.0f%% Jitter: %.2f Sync Time: %.2f (TS %.2f) %s\n", fabs(level) / cnetz->fsk_deviation * 100.0, jitter, sync_time, sync_time / 396.0, (level < 0) ? "NEGATIVE (phone's mode)" : "POSITIVE (base station's mode)"); PDEBUG_CHAN(DDSP, DEBUG_INFO, "RX Level: %.0f%% Standard deviation: %.0f%% Sync Time: %.2f (TS %.2f) %s\n", fabs(level) / cnetz->fsk_deviation * 100.0, stddev / fabs(level) * 100.0, sync_time, sync_time / 396.0, (level < 0) ? "NEGATIVE (phone's mode)" : "POSITIVE (base station's mode)");
if (cnetz->sender.loopback) { if (cnetz->sender.loopback) {
PDEBUG(DFRAME, DEBUG_NOTICE, "Received Telegramm in loopback test mode (opcode %d = %s)\n", opcode, definition_opcode[opcode].message_name); PDEBUG(DFRAME, DEBUG_NOTICE, "Received Telegramm in loopback test mode (opcode %d = %s)\n", opcode, definition_opcode[opcode].message_name);

3
src/cnetz/telegramm.h
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@ -61,7 +61,6 @@
typedef struct telegramm { typedef struct telegramm {
double level; /* average level of received sync sequence */ double level; /* average level of received sync sequence */
double sync_time; /* when did we receive the sync for this frame */ double sync_time; /* when did we receive the sync for this frame */
double jitter; /* phase jitter of sync sequence */
uint8_t opcode; uint8_t opcode;
/* used parameters depend on opcode */ /* used parameters depend on opcode */
uint8_t fuz_fuvst_nr; uint8_t fuz_fuvst_nr;
@ -124,6 +123,6 @@ int match_fuz(cnetz_t *cnetz, telegramm_t *telegramm, int cell);
int match_futln(telegramm_t *telegramm, uint8_t futln_nat, uint8_t futln_fuvst, uint16_t futln_rest); int match_futln(telegramm_t *telegramm, uint8_t futln_nat, uint8_t futln_fuvst, uint16_t futln_rest);
int detect_sync(uint64_t bitstream); int detect_sync(uint64_t bitstream);
void cnetz_decode_telegramm(cnetz_t *cnetz, const char *bits, double level, double sync_time, double jitter); void cnetz_decode_telegramm(cnetz_t *cnetz, const char *bits, double level, double sync_time, double stddev);
const char *cnetz_encode_telegramm(cnetz_t *cnetz); const char *cnetz_encode_telegramm(cnetz_t *cnetz);