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test of ssb

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This commit is contained in:
KubaPro010
2026-02-15 12:49:09 +01:00
parent 64e3f36e34
commit bffde6cb68
3 changed files with 70 additions and 0 deletions
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40
modulation/stereo_encoder.c
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@@ -1,23 +1,63 @@
#include "stereo_encoder.h"
#ifdef STEREO_SSB
static void init_delay_line(struct delay_line_t *delay_line, uint32_t sample_rate) {
delay_line->buffer = malloc(sample_rate * sizeof(float));
memset(delay_line->buffer, 0, sample_rate * sizeof(float));
}
static void set_delay_line(struct delay_line_t *delay_line, uint32_t new_delay) {
delay_line->delay = new_delay;
}
static inline float delay_line(struct delay_line_t *delay_line, float in) {
delay_line->buffer[delay_line->idx++] = in;
if (delay_line->idx >= delay_line->delay) delay_line->idx = 0;
return delay_line->buffer[delay_line->idx];
}
static void exit_delay_line(struct delay_line_t *delay_line) {
free(delay_line->buffer);
}
#endif
// Multiplier is the multiplier to get to 19 khz
void init_stereo_encoder(StereoEncoder* st, uint8_t multiplier, Oscillator* osc, float audio_volume, float pilot_volume) {
st->multiplier = multiplier;
st->osc = osc;
st->pilot_volume = pilot_volume;
st->audio_volume = audio_volume;
#ifdef STEREO_SSB
init_delay_line(&st->delay, 15); // 7*2+1
#endif
}
#ifdef STEREO_SSB
float stereo_encode(StereoEncoder* st, uint8_t enabled, float left, float right, firhilbf hilbert) {
#else
float stereo_encode(StereoEncoder* st, uint8_t enabled, float left, float right) {
#endif
float mid = (left+right) * 0.5f;
if(!enabled) return mid * st->audio_volume;
mid = delay_line(&st->delay, mid);
float half_audio = st->audio_volume * 0.5f;
float side = (left-right) * 0.5f;
#ifdef STEREO_SSB
float complex stereo_hilbert;
firhilbf_r2c_execute(hilbert, side, &stereo_hilbert);
float signalx2cos = get_oscillator_cos_multiplier_ni(st->osc, st->multiplier * 2.0f);
#endif
float signalx1 = get_oscillator_sin_multiplier_ni(st->osc, st->multiplier);
float signalx2 = get_oscillator_sin_multiplier_ni(st->osc, st->multiplier * 2.0f);
#ifdef STEREO_SSB
float stereo = (crealf(stereo_hilbert) * signalx2cos) - (cimagf(stereo_hilbert) * signalx2);
return (mid*half_audio) + (signalx1*st->pilot_volume) + (stereo * half_audio);
#else
return (mid*half_audio) + (signalx1*st->pilot_volume) + ((side*signalx2) * half_audio);
#endif
}

19
modulation/stereo_encoder.h
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@@ -1,7 +1,19 @@
#pragma once
#define STEREO_SSB
#include <stdint.h>
#include "../dsp/oscillator.h"
#ifdef STEREO_SSB
#include <liquid/liquid.h>
#include <complex.h>
typedef struct delay_line_t {
float *buffer;
uint32_t delay;
uint32_t idx;
} delay_line_t;
#endif
typedef struct
{
@@ -9,8 +21,15 @@ typedef struct
Oscillator* osc;
float audio_volume;
float pilot_volume;
#ifdef STEREO_SSB
struct delay_line_t delay;
#endif
} StereoEncoder;
void init_stereo_encoder(StereoEncoder *st, uint8_t multiplier, Oscillator *osc, float audio_volume, float pilot_volume);
#ifdef STEREO_SSB
float stereo_encode(StereoEncoder* st, uint8_t enabled, float left, float right, firhilbf hilbert);
#else
float stereo_encode(StereoEncoder* st, uint8_t enabled, float left, float right);
#endif

11
src/fm95.c
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@@ -83,6 +83,9 @@ typedef struct
float* rds_in;
Oscillator osc;
iirfilt_rrrf lpf_l, lpf_r;
#ifdef STEREO_SSB
firhilbf stereo_hilbert;
#endif
ResistorCapacitor preemp_l, preemp_r;
BS412Compressor bs412;
StereoEncoder stencode;
@@ -140,6 +143,10 @@ void cleanup_runtime(FM95_Runtime* runtime, const FM95_Config config) {
iirfilt_rrrf_destroy(runtime->lpf_l);
iirfilt_rrrf_destroy(runtime->lpf_r);
}
#ifdef STEREO_SSB
firhilbf_destroy(runtime->stereo_hilbert);
free(runtime->stencode.delay.buffer);
#endif
}
void cleanup_audio_runtime(FM95_Runtime *rt, const FM95_Options options) {
@@ -481,6 +488,10 @@ void init_runtime(FM95_Runtime* runtime, const FM95_Config config) {
runtime->lpf_r = iirfilt_rrrf_create_prototype(LIQUID_IIRDES_CHEBY2, LIQUID_IIRDES_LOWPASS, LIQUID_IIRDES_SOS, config.lpf_order, (config.lpf_cutoff/config.sample_rate), 0.0f, 1.0f, 60.0f);
}
#ifdef STEREO_SSB
runtime->stereo_hilbert = firhilbf_create(7, 60);
#endif
if(config.preemphasis != 0) {
init_preemphasis(&runtime->preemp_l, (float)config.preemphasis * 1.0e-6f, config.sample_rate, config.preemp_unity_freq);
init_preemphasis(&runtime->preemp_r, (float)config.preemphasis * 1.0e-6f, config.sample_rate, config.preemp_unity_freq);