generate the 66.5 inside the pll via the pilot

.vscode/.server-controller-port.log

@@ -1,5 +1,5 @@
 {
   "port": 13452,
-  "time": 1742717063787,
+  "time": 1742742025054,
   "version": "0.0.3"
 }

lib/filters.c

@@ -14,42 +14,46 @@ float hard_clip(float sample, float threshold) {
 	return fmaxf(-threshold, fminf(threshold, sample));
 }
 
-void init_pll(PLL *pll, float output_freq, float reference_freq, float loop_filter_bandwidth, int quadrature_mode, int sample_rate) {
+void init_pll(PLL *pll, int interpolation, int decimation, float freq, float loop_filter_bandwidth, int quadrature_mode, int sample_rate) {
 	pll->phase = 0.0f;
-    pll->freq = output_freq;
+	pll->freq = freq;
-    pll->ref_freq = reference_freq;
 	pll->loop_filter_state = 0.0f;
-    pll->kp = 2.0f * M_PI * loop_filter_bandwidth;
+	pll->kp = M_2PI * loop_filter_bandwidth;
 	pll->ki = 0.25f * pll->kp * pll->kp;
 	pll->sample_rate = sample_rate;
 	pll->quadrature_mode = quadrature_mode;
+	pll->last_output = 0.0f;
+	pll->interpolation = interpolation;
+	pll->decimation = decimation;
 }
 
-float apply_pll(PLL *pll, float ref_sample, float input_sample) {
+float apply_pll(PLL *pll, float ref_sample) {
 	float phase_error;
 
-    float output = sinf(pll->phase);
+	float vco_phase = pll->phase;
+	if(pll->quadrature_mode) vco_phase += M_PI/2.0f;
 
-    if (pll->quadrature_mode) {
+	float vco_output = sinf(pll->phase);
-        output = sinf(pll->phase + (M_PI / 2.0f));
+	if (pll->quadrature_mode) vco_output = sinf(pll->phase + (M_PI / 2.0f)); // 90 degrees
-    }
 
-    phase_error = ref_sample * input_sample;
+	phase_error = ref_sample * pll->last_output;
 
 	pll->loop_filter_state += pll->ki * phase_error / pll->sample_rate;
 	float loop_output = pll->loop_filter_state + pll->kp * phase_error;
 
-    float freq_adjustment = loop_output / (2.0f * M_PI);
+	float freq_adjustment = loop_output / M_2PI;
 	float instantaneous_freq = pll->freq + freq_adjustment;
 
-    pll->phase += 2.0f * M_PI * instantaneous_freq / pll->sample_rate;
+	pll->phase += M_2PI * instantaneous_freq / pll->sample_rate;
 
-    while (pll->phase >= 2.0f * M_PI) {
+	while (pll->phase >= M_2PI) {
-        pll->phase -= 2.0f * M_PI;
+		pll->phase -= M_2PI;
 	}
 	while (pll->phase < 0.0f) {
-        pll->phase += 2.0f * M_PI;
+		pll->phase += M_2PI;
 	}
 
-    return output;
+	pll->last_output = sinf((vco_phase*pll->interpolation)/pll->decimation);
+
+	return pll->last_output;
 }

lib/filters.h

@@ -19,12 +19,14 @@ float hard_clip(float sample, float threshold);
 typedef struct {
 	float phase;
 	float freq;
-    float ref_freq;
 	float loop_filter_state;
 	float kp;
 	float ki;
+	float last_output;
+	int interpolation;
+	int decimation;
 	int sample_rate;
 	int quadrature_mode;
 } PLL;
-void init_pll(PLL *pll, float output_freq, float refrence_freq, float loop_filter_bandwidth, int quadrature_mode, int sample_rate);
+void init_pll(PLL *pll, int interpolation, int decimation, float freq, float loop_filter_bandwidth, int quadrature_mode, int sample_rate);
-float apply_pll(PLL *pll, float ref_sample, float input_sample);
+float apply_pll(PLL *pll, float ref_sample);

src/fm95.c

@@ -35,13 +35,13 @@
 #define DEFAULT_MASTER_VOLUME 1.0f // Volume of everything combined, for calibration
 #define DEFAULT_AUDIO_VOLUME 1.0f // Audio volume, before clipper
 
-#define MONO_VOLUME 0.45f // L+R Signal
+#define MONO_VOLUME 0.45f
-#define PILOT_VOLUME 0.09f // 19 KHz Pilot
+#define PILOT_VOLUME 0.09f
-#define STEREO_VOLUME 0.45f // L-R signal, should be same as MONO
+#define STEREO_VOLUME 0.45f
-#define RDS_VOLUME 0.075f // RDS Volume, after dsb-sc
+#define RDS_VOLUME 0.075f
-#define RDS2_VOLUME 0.075f // RDS2 Volume
+#define RDS2_VOLUME 0.0675f
-#define SCA_VOLUME 0.1f // FM SCA signal, 10%
+#define SCA_VOLUME 0.1f
-#define MPX_VOLUME 1.0f // Passtrough
+#define MPX_VOLUME 1.0f
 #define MPX_CLIPPER_THRESHOLD 1.0f
 
 static volatile sig_atomic_t to_run = 1;
@@ -408,9 +408,6 @@ int main(int argc, char **argv) {
 	Oscillator osc;
 	init_oscillator(&osc, polar_stereo ? 31250.0 : 19000, sample_rate);
 
-    Oscillator rds2_osc;
-    init_oscillator(&rds2_osc, 66500, sample_rate);
-
 	FMModulator sca_mod;
 	init_fm_modulator(&sca_mod, sca_frequency, sca_deviation, sample_rate);
 
@@ -419,7 +416,7 @@ int main(int argc, char **argv) {
 	init_preemphasis(&preemp_r, preemphasis_tau, sample_rate);
 
 	PLL rds2_pll;
-    init_pll(&rds2_pll, 66500, 19000, 100, 1, sample_rate);
+	init_pll(&rds2_pll, 7, 2, 19000, 100, 1, sample_rate);
 	// #endregion
 
 	signal(SIGINT, stop);
@@ -498,7 +495,7 @@ int main(int argc, char **argv) {
 				float rds_carrier = get_oscillator_sin_multiplier_ni(&osc, 3);
 				output[i] += (current_rds_in*rds_carrier)*RDS_VOLUME;
 				if(!sca_on) {
-                    float rds2_carrier_66 = apply_pll(&rds2_pll, get_oscillator_sin_multiplier_ni(&osc, 1), get_oscillator_cos_sample(&rds2_osc));
+					float rds2_carrier_66 = apply_pll(&rds2_pll, get_oscillator_sin_multiplier_ni(&osc, 1));
 					output[i] += (current_rds2_in*rds2_carrier_66)*RDS2_VOLUME;
 				}
 			}