radio95/fm95
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Code Issues Activity

add functional lpf, remake hilbert

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This commit is contained in:
KubaPro010
2025-01-26 19:26:20 +01:00
parent d2663bdb9f
commit 16fa3f3702
7 changed files with 144 additions and 66 deletions
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26
src/fm95.c
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@@ -3,7 +3,7 @@
#include <getopt.h>
#define buffer_maxlength 12288
#define buffer_tlength_fragsize 8192
#define buffer_tlength_fragsize 12288
#define buffer_prebuf 16
#define DEFAULT_STEREO 1
@@ -43,6 +43,7 @@
#define SCA_VOLUME 0.1f
#define MPX_VOLUME 1.0f
#define LPF_CUTOFF 15000
volatile sig_atomic_t to_run = 1;
@@ -410,12 +411,16 @@ int main(int argc, char **argv) {
HilbertTransformer hilbert; // An Hilbert shifts a signal in quadrature, generating the I/Q data
init_hilbert(&hilbert);
DelayLine monoDelay; // Hilbert introduces a delay of 99 samples, this should be here to sync the mono with stereo to a sample
init_delay_line(&monoDelay, 99);
init_delay_line(&monoDelay, (HILBERT_TAPS-1)/2);
ResistorCapacitor preemp_l, preemp_r;
init_rc_tau(&preemp_l, preemphasis_tau, SAMPLE_RATE);
init_rc_tau(&preemp_r, preemphasis_tau, SAMPLE_RATE);
FrequencyFilter lpf_l, lpf_r;
init_lpf(&lpf_l, LPF_CUTOFF, SAMPLE_RATE);
init_lpf(&lpf_r, LPF_CUTOFF, SAMPLE_RATE);
signal(SIGINT, stop);
signal(SIGTERM, stop);
@@ -454,8 +459,8 @@ int main(int argc, char **argv) {
float current_mpx_in = mpx_in[i];
float current_sca_in = sca_in[i];
float ready_l = l_in;
float ready_r = r_in;
float ready_l = apply_freqeuncy_filter(&lpf_l, r_in);
float ready_r = apply_freqeuncy_filter(&lpf_r, l_in);
ready_l = apply_pre_emphasis(&preemp_l, ready_l)*2;
ready_r = apply_pre_emphasis(&preemp_r, ready_r)*2;
ready_l = hard_clip(ready_l, clipper_threshold);
@@ -473,9 +478,9 @@ int main(int argc, char **argv) {
stereo += 0.2;
apply_hilbert(&hilbert, stereo, &stereo_i, &stereo_q); // Compute I/Q
#ifdef USB
float signal = (stereo_i*stereo_carrier_cos+stereo_q*(stereo_carrier*0.775f));
float signal = (stereo_i*stereo_carrier_cos+stereo_q*(stereo_carrier));
#else
float signal = (stereo_i*stereo_carrier_cos-stereo_q*(stereo_carrier*0.775f));
float signal = (stereo_i*stereo_carrier_cos-stereo_q*(stereo_carrier));
#endif
output[i] = delay_line(&monoDelay, mono)*MONO_VOLUME +
signal*STEREO_VOLUME;
@@ -496,14 +501,10 @@ int main(int argc, char **argv) {
float stereo_i, stereo_q;
apply_hilbert(&hilbert, stereo, &stereo_i, &stereo_q); // Compute I/Q
#ifdef USB
float signal = (stereo_i*stereo_carrier_cos+stereo_q*(stereo_carrier*0.775f));
#else
float signal = (stereo_i*stereo_carrier_cos-stereo_q*(stereo_carrier*0.775f));
#endif
output[i] = delay_line(&monoDelay, mono)*MONO_VOLUME +
pilot*PILOT_VOLUME +
signal*STEREO_VOLUME;
(stereo_i*stereo_carrier_cos+stereo_q*stereo_carrier)*STEREO_VOLUME;
if(strlen(audio_mpx_device) != 0) output[i] += current_mpx_in*MPX_VOLUME;
if(strlen(audio_sca_device) != 0) output[i] += modulate_fm(&sca_mod, hard_clip(current_sca_in, sca_clipper_threshold))*SCA_VOLUME;
} else {
@@ -544,7 +545,6 @@ int main(int argc, char **argv) {
snd_pcm_close(output_handle);
snd_pcm_hw_params_free(output_params);
}
exit_hilbert(&hilbert);
exit_delay_line(&monoDelay);
return 0;
}