reduce sampling rate

gen_wave.py

@@ -1,5 +1,5 @@
-PLOT = True
-FFT = PLOT and True
+PLOT = False
+FFT = PLOT and False
 
 import math
 import io, os
@@ -9,7 +9,7 @@ if FFT: import numpy as np
 DATA_RATE = 1187.5
 SIZE_RATIO = 1
 
-ratio = 16
+ratio = 4
 sample_rate = DATA_RATE*ratio
 print(f"{sample_rate=}")
 if not sample_rate.is_integer(): raise ValueError("Need a even value")
@@ -92,4 +92,4 @@ def generate():
 generate()
 
 outc.close()
-outh.close()
+outh.close()

src/modulator.c

@@ -146,5 +146,5 @@ float get_rds_sample(RDSModulator* rdsMod, uint8_t stream) {
 	if (rdsMod->data[stream].out_sample_index == SAMPLE_BUFFER_SIZE) rdsMod->data[stream].out_sample_index = 0;
 	
 	uint8_t tooutput = rdsMod->params.rdsgen > stream ? 1 : 0;
-	return sample*rdsMod->params.level*tooutput;
+	return sample*rdsMod->params.level*tooutput / 3.5; // 3.5 volts from piracz
 }

src/rds.h

@@ -10,9 +10,9 @@
 
 #define GROUP_LENGTH		4
 #define BITS_PER_GROUP		(GROUP_LENGTH * (BLOCK_SIZE + POLY_DEG))
-#define RDS_SAMPLE_RATE		19000
-#define SAMPLES_PER_BIT     16
-#define FILTER_SIZE	 16
+#define RDS_SAMPLE_RATE		4750
+#define SAMPLES_PER_BIT     4
+#define FILTER_SIZE	 4
 #define SAMPLE_BUFFER_SIZE	(SAMPLES_PER_BIT + FILTER_SIZE)
 
 #define STREAMS 2

src/waveforms.c

@@ -6,5 +6,5 @@
    Released under the GNU GPL v3 license.
 */
 
-float waveform_biphase[16] = {0.0, 0.3826834323650898, 0.7071067811865475, 0.9238795325112867, 1.0, 0.9238795325112867, 0.7071067811865476, 0.3826834323650899, 1.2246467991473532e-16, -0.3826834323650892, -0.7071067811865475, -0.9238795325112868, -1.0, -0.923879532511287, -0.7071067811865477, -0.3826834323650904};
+float waveform_biphase[4] = {0.0, 1.0, 1.2246467991473532e-16, -1.0};
 

src/waveforms.h

@@ -6,4 +6,4 @@
    Released under the GNU GPL v3 license.
 */
 
-extern float waveform_biphase[16];
+extern float waveform_biphase[4];