cleanup

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.10)
 
-project(rds95 VERSION 1.3)
+project(rds95 VERSION 1.4)
 
 add_compile_options(-Wall -Werror -Wextra -pedantic -O2 -std=c18 -march=native -DVERSION=\"${PROJECT_VERSION}\")
 

gen_wave.py

@@ -7,38 +7,12 @@ if PLOT: import matplotlib.pyplot as plt
 if FFT: import numpy as np
 
 DATA_RATE = 1187.5
-SIZE_RATIO = 1
 
 ratio = 4
 sample_rate = DATA_RATE*ratio
 print(f"{sample_rate=}")
 if not sample_rate.is_integer(): raise ValueError("Need a even value")
 
-# this is modified from ChristopheJacquet's pydemod
-def rrcosfilter(NumSamples):
-	T_delta = 1/float(sample_rate)
-	sample_num = list(range(NumSamples))
-	h_rrc = [0.0] * NumSamples
-	SymbolPeriod = 1/(2*DATA_RATE)
-
-	for x in sample_num:
-		t = (x-NumSamples/2)*T_delta
-		if t == 0.0: h_rrc[x] = 1.0 - 1 + (4/math.pi)
-		elif t == SymbolPeriod/4: h_rrc[x] = (1/math.sqrt(2))*(((1+2/math.pi) * (math.sin(math.pi/4))) + ((1-2/math.pi)*(math.cos(math.pi/4))))
-		elif t == -SymbolPeriod/4: h_rrc[x] = (1/math.sqrt(2))*(((1+2/math.pi) * (math.sin(math.pi/4))) + ((1-2/math.pi)*(math.cos(math.pi/4))))
-		else: h_rrc[x] = (4*(t/SymbolPeriod)*math.cos(math.pi*t*2/SymbolPeriod)) / (math.pi*t*(1-(4*t/SymbolPeriod)*(4*t/SymbolPeriod))/SymbolPeriod)
-	blackman = [0.42 + 0.5*math.cos(math.pi*i/(NumSamples-1)) + 0.08*math.cos(2.0*math.pi*i/(NumSamples-1)) for i in range(NumSamples)]
-	h_rrc = [h_rrc[i] * blackman[i] for i in range(NumSamples)]
-
-	return h_rrc
-
-def convolve(a, b):
-	out = [0] * (len(a) + len(b) - 1)
-	for i in range(len(a)):
-		for j in range(len(b)):
-			out[i+j] += a[i] * b[j]
-	return out
-
 PATH = os.path.dirname(os.path.abspath(__file__))
 
 outc = io.open(f"{PATH}/src/waveforms.c", mode="w", encoding="utf8")
@@ -60,7 +34,7 @@ outh.write(header)
 def generate():
 	t = [i / sample_rate for i in range(ratio)]
 	out = [math.sin(2 * math.pi * DATA_RATE * time) for time in t]
-	print(f"{len(out)=} {len(out)/sample_rate=} {1/DATA_RATE=}")
+	print(f"{len(out)=}")
 
 	if PLOT:
 		plt.plot(out*4, label="out")

src/modulator.c

@@ -90,7 +90,7 @@ void init_rds_modulator(RDSModulator* rdsMod, RDSEncoder* enc) {
 
 	rdsMod->enc = enc;
 
-	if(STREAMS > 0) rdsMod->data[1].symbol_shifting.symbol_shift = SAMPLES_PER_BIT / 2;
+	if(STREAMS > 0) rdsMod->data[1].symbol_shifting.symbol_shift = FILTER_SIZE / 2;
 
 	for (uint8_t i = 0; i < 2; i++) {
 		for (uint16_t j = 0; j < FILTER_SIZE; j++) {
@@ -108,7 +108,7 @@ void init_rds_modulator(RDSModulator* rdsMod, RDSEncoder* enc) {
 
 float get_rds_sample(RDSModulator* rdsMod, uint8_t stream) {
 	float *cur_waveform;
-	if (rdsMod->data[stream].sample_count == SAMPLES_PER_BIT) {
+	if (rdsMod->data[stream].sample_count == FILTER_SIZE) {
 		if (rdsMod->data[stream].bit_pos == BITS_PER_GROUP) {
 			get_rds_bits(rdsMod->enc, rdsMod->data[stream].bit_buffer, stream);
 			rdsMod->data[stream].bit_pos = 0;
@@ -126,7 +126,7 @@ float get_rds_sample(RDSModulator* rdsMod, uint8_t stream) {
 			if (idx == SAMPLE_BUFFER_SIZE) idx = 0;
 		}
 
-		rdsMod->data[stream].in_sample_index += SAMPLES_PER_BIT;
+		rdsMod->data[stream].in_sample_index += FILTER_SIZE;
 		if (rdsMod->data[stream].in_sample_index == SAMPLE_BUFFER_SIZE) rdsMod->data[stream].in_sample_index = 0;
 
 		rdsMod->data[stream].sample_count = 0;

src/rds.h

@@ -11,9 +11,8 @@
 #define GROUP_LENGTH		4
 #define BITS_PER_GROUP		(GROUP_LENGTH * (BLOCK_SIZE + POLY_DEG))
 #define RDS_SAMPLE_RATE		4750
-#define SAMPLES_PER_BIT     4
 #define FILTER_SIZE	 4
-#define SAMPLE_BUFFER_SIZE	(SAMPLES_PER_BIT + FILTER_SIZE)
+#define SAMPLE_BUFFER_SIZE	(FILTER_SIZE*2)
 
 #define STREAMS 2
 

src/rds95.c

@@ -94,8 +94,8 @@ int main(int argc, char **argv) {
 	format.rate = RDS_SAMPLE_RATE;
 
 	buffer.prebuf = 0;
-	buffer.tlength = NUM_MPX_FRAMES*4;
-	buffer.maxlength = NUM_MPX_FRAMES*4;
+	buffer.tlength = NUM_MPX_FRAMES*2;
+	buffer.maxlength = NUM_MPX_FRAMES*2;
 
 	rds_device = pa_simple_new(
 		NULL,