Fixed FFT scaling, moved logging to stderr
This commit is contained in:
Karlis Goba
parent
5de7436d87
commit
ccc80ff9e3
2 changed files with 38 additions and 20 deletions
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@ -2,11 +2,11 @@
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#include <stdio.h>
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#define LOG_INFO 0
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#define LOG_WARN 1
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#define LOG_ERROR 2
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#define LOG_FATAL 3
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#define LOG_DEBUG 0
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#define LOG_INFO 1
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#define LOG_WARN 2
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#define LOG_ERROR 3
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#define LOG_FATAL 4
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#define LOG(level, ...) if (level >= LOG_LEVEL) printf(__VA_ARGS__)
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#define LOG(level, ...) if (level >= LOG_LEVEL) fprintf(stderr, __VA_ARGS__)
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@ -9,16 +9,20 @@
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#include "ft8/constants.h"
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#include "common/wave.h"
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#include "common/debug.h"
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#include "fft/kiss_fftr.h"
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#define LOG_LEVEL LOG_INFO
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const int kMax_candidates = 100;
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const int kLDPC_iterations = 20;
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const int kMax_decoded_messages = 50;
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const int kMax_message_length = 20;
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void usage() {
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printf("Decode a 15-second WAV file.\n");
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fprintf(stderr, "Decode a 15-second WAV file.\n");
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}
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@ -55,6 +59,7 @@ float blackman_i(int i, int N) {
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void extract_power(const float signal[], int num_blocks, int num_bins, uint8_t power[]) {
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const int block_size = 2 * num_bins; // Average over 2 bins per FSK tone
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const int nfft = 2 * block_size; // We take FFT of two blocks, advancing by one
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const float fft_norm = 2.0f / nfft;
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float window[nfft];
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for (int i = 0; i < nfft; ++i) {
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@ -64,15 +69,13 @@ void extract_power(const float signal[], int num_blocks, int num_bins, uint8_t p
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size_t fft_work_size;
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kiss_fftr_alloc(nfft, 0, 0, &fft_work_size);
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printf("N_FFT = %d\n", nfft);
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printf("FFT work area = %lu\n", fft_work_size);
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LOG(LOG_INFO, "N_FFT = %d\n", nfft);
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LOG(LOG_INFO, "FFT work area = %lu\n", fft_work_size);
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void *fft_work = malloc(fft_work_size);
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kiss_fftr_cfg fft_cfg = kiss_fftr_alloc(nfft, 0, fft_work, &fft_work_size);
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// Currently bit unsure about the scaling factor of kiss FFT
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int offset = 0;
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float fft_norm = 1.0f / nfft / sqrtf(nfft);
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float max_mag = -100.0f;
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for (int i = 0; i < num_blocks; ++i) {
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// Loop over two possible time offsets (0 and block_size/2)
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@ -90,8 +93,8 @@ void extract_power(const float signal[], int num_blocks, int num_bins, uint8_t p
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// Compute log magnitude in decibels
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for (int j = 0; j < nfft/2 + 1; ++j) {
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float mag2 = fft_norm * (freqdata[j].i * freqdata[j].i + freqdata[j].r * freqdata[j].r);
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mag_db[j] = 10.0f * log10f(1E-10f + mag2);
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float mag2 = (freqdata[j].i * freqdata[j].i + freqdata[j].r * freqdata[j].r);
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mag_db[j] = 10.0f * log10f(1E-10f + mag2 * fft_norm * fft_norm);
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}
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// Loop over two possible frequency bin offsets (for averaging)
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@ -102,7 +105,7 @@ void extract_power(const float signal[], int num_blocks, int num_bins, uint8_t p
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float db = (db1 + db2) / 2;
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// Scale decibels to unsigned 8-bit range and clamp the value
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int scaled = (int)(2 * (db + 100));
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int scaled = (int)(2 * (db + 120));
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power[offset] = (scaled < 0) ? 0 : ((scaled > 255) ? 255 : scaled);
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++offset;
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@ -112,20 +115,34 @@ void extract_power(const float signal[], int num_blocks, int num_bins, uint8_t p
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}
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}
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printf("Max magnitude: %.1f dB\n", max_mag);
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LOG(LOG_INFO, "Max magnitude: %.1f dB\n", max_mag);
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free(fft_work);
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}
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void normalize_signal(float *signal, int num_samples) {
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float max_amp = 1E-5f;
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for (int i = 0; i < num_samples; ++i) {
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float amp = fabsf(signal[i]);
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if (amp > max_amp) {
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max_amp = amp;
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}
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}
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for (int i = 0; i < num_samples; ++i) {
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signal[i] /= max_amp;
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}
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}
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void print_tones(const uint8_t *code_map, const float *log174) {
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for (int k = 0; k < 3 * FT8_ND; k += 3) {
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uint8_t max = 0;
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if (log174[k + 0] > 0) max |= 4;
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if (log174[k + 1] > 0) max |= 2;
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if (log174[k + 2] > 0) max |= 1;
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printf("%d", code_map[max]);
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LOG(LOG_DEBUG, "%d", code_map[max]);
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}
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printf("\n");
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LOG(LOG_DEBUG, "\n");
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}
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@ -146,6 +163,7 @@ int main(int argc, char **argv) {
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if (rc < 0) {
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return -1;
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}
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normalize_signal(signal, num_samples);
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const float fsk_dev = 6.25f; // tone deviation in Hz and symbol rate
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@ -154,7 +172,7 @@ int main(int argc, char **argv) {
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const int block_size = 2 * num_bins;
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const int num_blocks = (num_samples - (block_size/2) - block_size) / block_size;
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printf("%d blocks, %d bins\n", num_blocks, num_bins);
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LOG(LOG_INFO, "%d blocks, %d bins\n", num_blocks, num_bins);
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// Compute FFT over the whole signal and store it
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uint8_t power[num_blocks * 4 * num_bins];
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@ -220,10 +238,10 @@ int main(int argc, char **argv) {
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// Fake WSJT-X-like output for now
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int snr = 0; // TODO: compute SNR
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printf("000000 %3d %4.1f %4d ~ %s\n", idx, time_sec, (int)(freq_hz + 0.5f), message);
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printf("000000 %3d %4.1f %4d ~ %s\n", cand.score, time_sec, (int)(freq_hz + 0.5f), message);
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}
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}
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printf("Decoded %d messages\n", num_decoded);
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LOG(LOG_INFO, "Decoded %d messages\n", num_decoded);
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return 0;
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}
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