AFG/dump1090
3
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity

Tweaks to noise measurements.

Browse source
This commit is contained in:
Oliver Jowett 2015-06-16 10:13:25 +01:00
parent 7d4eaf6a48
commit 21bdc45bf0
7 changed files with 48 additions and 50 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
convert.c
View file

@ -65,8 +65,8 @@ static void convert_uc8_nodc_power(void *iq_data,
{
uint16_t *in = iq_data;
unsigned i;
uint16_t mag;
uint64_t power = 0;
uint16_t mag;
MODES_NOTUSED(state);
@ -74,45 +74,46 @@ static void convert_uc8_nodc_power(void *iq_data,
for (i = 0; i < (nsamples>>3); ++i) {
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
}
for (i = 0; i < (nsamples&7); ++i) {
mag = Modes.maglut[*in++];
*mag_data++ = mag;
power += mag*mag;
power += (uint32_t)mag * (uint32_t)mag;
}
if (out_power)
*out_power = power / (65535.0 * 65535.0);
if (out_power) {
*out_power = power / 65535.0 / 65535.0;
}
}
static void convert_uc8_generic(void *iq_data,

56
demod_2400.c
View file

@ -161,7 +161,7 @@ void demodulate2400(struct mag_buf *mag)
uint16_t *m = mag->data;
uint32_t mlen = mag->length;
double total_signal_power = 0.0;
uint64_t sum_scaled_signal_power = 0;
memset(&mm, 0, sizeof(mm));
msg = msg1;
@ -412,30 +412,6 @@ void demodulate2400(struct mag_buf *mag)
mm.score = bestscore;
mm.bFlags = mm.correctedbits = 0;
// measure signal power
{
uint64_t signal_power_sum = 0;
double signal_power;
int signal_len = msglen*12/5 + 1;
int k;
for (k = 0; k < signal_len; ++k) {
uint64_t s = m[j+19+k];
signal_power_sum += s * s;
}
mm.signalLevel = signal_power = signal_power_sum / MAX_POWER / signal_len;
Modes.stats_current.signal_power_sum += signal_power;
Modes.stats_current.signal_power_count ++;
if (signal_power > Modes.stats_current.peak_signal_power)
Modes.stats_current.peak_signal_power = signal_power;
if (signal_power > 0.50119)
Modes.stats_current.strong_signal_count++; // signal power above -3dBFS
total_signal_power += signal_power_sum / MAX_POWER;
}
// Decode the received message
{
int result = decodeModesMessage(&mm, bestmsg);
@ -450,6 +426,29 @@ void demodulate2400(struct mag_buf *mag)
}
}
// measure signal power
{
double signal_power;
uint64_t scaled_signal_power = 0;
int signal_len = msglen*12/5;
int k;
for (k = 0; k < signal_len; ++k) {
uint32_t mag = m[j+19+k];
scaled_signal_power += mag * mag;
}
signal_power = scaled_signal_power / 65535.0 / 65535.0;
mm.signalLevel = signal_power / signal_len;
Modes.stats_current.signal_power_sum += signal_power;
Modes.stats_current.signal_power_count += signal_len;
sum_scaled_signal_power += scaled_signal_power;
if (mm.signalLevel > Modes.stats_current.peak_signal_power)
Modes.stats_current.peak_signal_power = mm.signalLevel;
if (mm.signalLevel > 0.50119)
Modes.stats_current.strong_signal_count++; // signal power above -3dBFS
}
// Skip over the message:
// (we actually skip to 8 bits before the end of the message,
@ -457,7 +456,7 @@ void demodulate2400(struct mag_buf *mag)
// where the preamble of the second message clobbered the last
// few bits of the first message, but the message bits didn't
// overlap)
j += (8 + msglen - 8)*12/5 - 1;
j += msglen*12/5;
// Pass data to the next layer
useModesMessage(&mm);
@ -465,8 +464,9 @@ void demodulate2400(struct mag_buf *mag)
/* update noise power if measured */
if (Modes.measure_noise) {
Modes.stats_current.noise_power_sum += (mag->total_power - total_signal_power) / mag->length;
Modes.stats_current.noise_power_count ++;
double sum_signal_power = sum_scaled_signal_power / 65535.0 / 65535.0;
Modes.stats_current.noise_power_sum += (mag->total_power - sum_signal_power);
Modes.stats_current.noise_power_count += mag->length;
}
}

2
dump1090.c
View file

@ -175,7 +175,6 @@ void modesInit(void) {
Modes.trailing_samples = (MODES_PREAMBLE_US + MODES_LONG_MSG_BITS + 16) * 1e-6 * Modes.sample_rate;
if ( ((Modes.maglut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) ||
((Modes.magsqlut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) ||
((Modes.log10lut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) )
{
fprintf(stderr, "Out of memory allocating data buffer.\n");
@ -231,7 +230,6 @@ void modesInit(void) {
if (magsq > 1)
magsq = 1;
Modes.magsqlut[le16toh((i*256)+q)] = (uint16_t) round(magsq * 65535.0);
Modes.maglut[le16toh((i*256)+q)] = (uint16_t) round(sqrtf(magsq) * 65535.0);
}
}

1
dump1090.h
View file

@ -268,7 +268,6 @@ struct { // Internal state
int fd; // --ifile option file descriptor
input_format_t input_format; // --iformat option
uint16_t *maglut; // I/Q -> Magnitude lookup table
uint16_t *magsqlut; // I/Q -> Magnitude-squared lookup table
uint16_t *log10lut; // Magnitude -> log10 lookup table
int exit; // Exit from the main loop when true

4
net_io.c
View file

@ -853,9 +853,9 @@ static char * appendStatsJson(char *p,
p += snprintf(p, end-p, "]");
if (st->signal_power_count > 0)
if (st->signal_power_sum > 0 && st->signal_power_count > 0)
p += snprintf(p, end-p,",\"signal\":%.1f", 10 * log10(st->signal_power_sum / st->signal_power_count));
if (st->noise_power_count > 0)
if (st->noise_power_sum > 0 && st->noise_power_count > 0)
p += snprintf(p, end-p,",\"noise\":%.1f", 10 * log10(st->noise_power_sum / st->noise_power_count));
if (st->peak_signal_power > 0)
p += snprintf(p, end-p,",\"peak_signal\":%.1f", 10 * log10(st->peak_signal_power));

6
stats.c
View file

@ -89,17 +89,17 @@ void display_stats(struct stats *st) {
for (j = 1; j <= Modes.nfix_crc; ++j)
printf(" %u accepted with %d-bit error repaired\n", st->demod_accepted[j], j);
if (st->noise_power_count) {
if (st->noise_power_sum > 0 && st->noise_power_count > 0) {
printf(" %.1f dBFS noise floor\n",
10 * log10(st->noise_power_sum / st->noise_power_count));
}
if (st->signal_power_count) {
if (st->signal_power_sum > 0 && st->signal_power_count > 0) {
printf(" %.1f dBFS mean signal power\n",
10 * log10(st->signal_power_sum / st->signal_power_count));
}
if (st->peak_signal_power) {
if (st->peak_signal_power > 0) {
printf(" %.1f dBFS peak signal power\n",
10 * log10(st->peak_signal_power));
}

4
stats.h
View file

@ -73,11 +73,11 @@ struct stats {
// noise floor:
double noise_power_sum;
uint32_t noise_power_count;
uint64_t noise_power_count;
// mean signal power:
double signal_power_sum;
uint32_t signal_power_count;
uint64_t signal_power_count;
// peak signal power seen
double peak_signal_power;