Gray Mapping

This commit is contained in:
2025-10-23 13:03:14 +02:00
parent b4a9fc0cec
commit d3e45f775b
5 changed files with 272 additions and 140 deletions

View File

@ -14,27 +14,23 @@ struct qam_system_s {
double Ts; // Temps d'échantillionage
int N; // Nombre d'échantillions
double Fc; // Fréquence de la porteuse
double complex** constellation; // Tableau de symboles I + j Q
double complex* constellation; // Tableau de symboles I + j Q 1D
};
typedef struct qam_system_s qam_system;
// Initialisation de la constellation (double tableau de taille sqrt(M)),
// ToDo : changer à un tableau à 1 dimension pour éviter de calculer sqrt(M)
void init_constellation (qam_system* qam) {
int sm = (int)sqrt(qam->M);
qam->constellation = (double complex**)malloc(sizeof(double complex*) * sm);
for (int i = 0; i < sm; i++) {
qam->constellation[i] = (double complex*)malloc(sizeof(double complex) * sm);
}
qam->constellation = (double complex*)malloc(sizeof(double complex) * qam->M);
double norm_factor = sqrt((double)(qam->M - 1) / 3.0); // Pour puissance unitaire
for (int i = 0; i < sm; i++) {
double complex ip = -(sm - 1) + 2 * i;
double ip = -(sm - 1) + 2 * i;
for (int j = 0; j < sm; j++) {
double complex qp = -(sm - 1) + 2 * j;
qam->constellation[i][j] = (ip + I * qp) / norm_factor;
double qp = -(sm - 1) + 2 * j;
int idx = i * sm + j;
qam->constellation[idx] = (ip + I * qp) / norm_factor;
}
}
}
@ -81,26 +77,14 @@ void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bit
double min_d = INFINITY;
int i_cl = 0;
int j_cl = 0;
for (int i = 0; i < sm; i++) {
for (int j = 0; j < sm; j++) {
double d = cabs(r - qam->constellation[i][j]);
for (int idx = 0; idx < qam->M; idx++) {
double d = cabs(r - qam->constellation[idx]);
if (d < min_d) {
min_d = d;
i_cl = i;
j_cl = j;
i_cl = idx / sm;
j_cl = idx % sm;
}
}
}
/*
// Ancienne methode (non gray)
// index du symbole (id) : même mappage que dans bits_to_symbols()
int id = i_cl * sm + j_cl;
for (int b = 0; b < qam->k; b++) {
bits_hat[k * qam->k + b] = (id >> (qam->k - 1 - b)) & 1;
}
*/
// Gray mapping
if (qam->k % 2 != 0) {
@ -141,20 +125,6 @@ void add_noise (double complex* s, int len, double sigma) {
}
// Changer le tableau de bits en boolen ou alors la represenation binaire et shifter pour extraire les bits (pas bien si M plus grand)
/*void bits_to_symbols (qam_system* qam, uint8_t* bits, int nb_bits, double complex* symbols) {
int nb_symbols = nb_bits / qam->k;
int sm = sqrt(qam->M);
for (int k = 0; k < nb_symbols; k++) {
int id = 0;
for (int b = 0 ; b < qam->k; b++) {
id = id * 2 + bits[k * qam->k + b];
}
int i = id / sm;
int j = id % sm;
symbols[k] = qam->constellation[i][j];
}
}*/
void bits_to_symbols (qam_system* qam, uint8_t* bits, int nb_bits, double complex* symbols) {
int nb_symbols = nb_bits / qam->k;
int sm = (int)sqrt(qam->M);
@ -182,7 +152,7 @@ void bits_to_symbols (qam_system* qam, uint8_t* bits, int nb_bits, double comple
printf("bits_to_symbols : IOOR i_gray = %d j_gray = %d sm = %d \n", i_gray, j_gray, sm);
exit(1);
}
symbols[sym] = qam->constellation[i_gray][j_gray];
symbols[sym] = qam->constellation[i_gray * sm + j_gray];
}
}
@ -211,7 +181,8 @@ void fill_constellation_data(qam_system* qam, FILE *fp_ref) {
int sm = (int)sqrt(qam->M);
for (int i = 0; i < sm; i++) {
for (int j = 0; j < sm; j++) {
fprintf(fp_ref, "% .8f % .8f\n", creal(qam->constellation[i][j]), cimag(qam->constellation[i][j]));
int idx = i * sm + j;
fprintf(fp_ref, "% .8f % .8f\n", creal(qam->constellation[idx]), cimag(qam->constellation[idx]));
}
}
}
@ -241,6 +212,7 @@ void free_constellation(qam_system* qam) {
for (int i = 0; i < sm; i++)
free(qam->constellation[i]);
free(qam->constellation);
}
int main () {

104
QAM/save/2/debug.py Normal file
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@ -0,0 +1,104 @@
#!/usr/bin/env python3
import pyqtgraph as pg
from pyqtgraph.Qt import QtWidgets, QtCore
import numpy as np
import sys, os
# -------------------- Fichiers de données --------------------
REF_FILE = "constellation_ref.dat"
RX_FILE = "constellation.dat"
ERROR_FILE = "pll_error.dat"
# -------------------- Fonctions de chargement --------------------
def load_points(filename):
if os.path.exists(filename):
return np.loadtxt(filename)
else:
return np.zeros((0,2))
def load_error(filename):
if os.path.exists(filename):
return np.loadtxt(filename)
else:
return np.zeros((0,2))
# -------------------- Application --------------------
app = QtWidgets.QApplication(sys.argv)
win = pg.GraphicsLayoutWidget(show=True, title="Constellation")
win.resize(900, 900)
win.setBackground('#0a0a0a') # fond noir profond
plot = win.addPlot()
plot.setAspectLocked(True) # axes égaux
# -------------------- Axes stylés --------------------
plot.getAxis('left').setPen(pg.mkPen('#AAA', width=2))
plot.getAxis('bottom').setPen(pg.mkPen('#AAA', width=2))
plot.getAxis('left').setTextPen(pg.mkPen('#EEE'))
plot.getAxis('bottom').setTextPen(pg.mkPen('#EEE'))
plot.setLabel('left', 'Quadrature (Q)', color='#EEE', size='12pt')
plot.setLabel('bottom', 'In-phase (I)', color='#EEE', size='12pt')
# -------------------- Grille subtile --------------------
grid = pg.GridItem()
grid.setPen(pg.mkPen('#444', width=1, style=QtCore.Qt.DotLine))
plot.addItem(grid)
# -------------------- Chargement initial --------------------
ref_data = load_points(REF_FILE)
rx_data = load_points(RX_FILE)
error_data = load_error(ERROR_FILE)
# Points référence
ref_plot = plot.plot(ref_data[:,0], ref_data[:,1],
pen=None,
symbol='o',
symbolSize=10,
symbolBrush=pg.mkBrush('#1E90FF'), # bleu vif
symbolPen=None,
name='Référence')
# Points reçus
rx_plot = plot.plot(rx_data[:,0], rx_data[:,1],
pen=None,
symbol='x',
symbolSize=6,
symbolBrush=pg.mkBrush('#FF4500'), # orange vif
symbolPen=None,
name='Reçu')
# PLL error en vert
error_plot = plot.plot(error_data[:,0], error_data[:,1],
pen=pg.mkPen('#00FF00', width=2),
symbol=None,
name='PLL error')
# -------------------- Légende stylée --------------------
legend = plot.addLegend()
for item in legend.items:
item[1].setPen(pg.mkPen('#FFF', width=2))
# -------------------- Timer pour mise à jour dynamique --------------------
def update():
ref_data = load_points(REF_FILE)
rx_data = load_points(RX_FILE)
error_data = load_error(ERROR_FILE)
if ref_data.size > 0:
ref_plot.setData(ref_data[:,0], ref_data[:,1])
if rx_data.size > 0:
rx_plot.setData(rx_data[:,0], rx_data[:,1])
if error_data.size > 0:
error_plot.setData(error_data[:,0], error_data[:,1])
timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(500) # ms
# -------------------- Anti-aliasing --------------------
pg.setConfigOptions(antialias=True)
# -------------------- Exécution --------------------
if __name__ == '__main__':
sys.exit(app.exec_())

View File

@ -39,36 +39,16 @@ void init_constellation (qam_system* qam) {
}
}
// Calcul du bruit gaussien pour un sigma donné
// Formule de Box-Muller
double gaussian_noise (double sigma) {
double u1 = (rand() + 1) / ((double)RAND_MAX + 2);
double u2 = (rand() + 1) / ((double)RAND_MAX + 2);
return sigma * sqrt(-2 * log(u1)) * cos(2 * M_PI * u2);
int bin_to_gray (int x) {
return x ^ (x >> 1);
}
// Ajout du bruit
void add_noise (double complex* s, int len, double sigma) {
for (int i = 0; i < len; i++) {
double nr = gaussian_noise(sigma);
double ni = gaussian_noise(sigma);
s[i] += nr + I * ni;
}
}
// Changer le tableau de bits en boolen ou alors la represenation binaire et shifter pour extraire les bits (pas bien si M plus grand)
void bits_to_symbols (qam_system* qam, uint8_t* bits, int nb_bits, double complex* symbols) {
int nb_symbols = nb_bits / qam->k;
int sm = sqrt(qam->M);
for (int k = 0; k < nb_symbols; k++) {
int id = 0;
for (int b = 0 ; b < qam->k; b++) {
id = id * 2 + bits[k * qam->k + b];
}
int i = id / sm;
int j = id % sm;
symbols[k] = qam->constellation[i][j];
}
// Iteration de XOR
int gray_to_bin(int g) {
int b = g;
while (g >>= 1)
b ^= g;
return b;
}
// Modulation QAM
@ -112,12 +92,146 @@ void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bit
}
}
/*
// Ancienne methode (non gray)
// index du symbole (id) : même mappage que dans bits_to_symbols()
int id = i_cl * sm + j_cl;
for (int b = 0; b < qam->k; b++) {
bits_hat[k * qam->k + b] = (id >> (qam->k - 1 - b)) & 1;
}
*/
// Gray mapping
if (qam->k % 2 != 0) {
printf("demodulate : k pair (k = %d)\n", qam->k);
exit(1);
}
int bits_per_axis = qam->k / 2;
int i_bin = gray_to_bin(i_cl);
int j_bin = gray_to_bin(j_cl);
for (int b = 0; b < bits_per_axis; b++) {
bits_hat[k * qam->k + b] = (i_bin >> (bits_per_axis - 1 - b)) & 1;
bits_hat[k * qam->k + bits_per_axis + b] = (j_bin >> (bits_per_axis - 1 - b)) & 1;
}
}
}
// Calcul du bruit gaussien pour un sigma donné
// Formule de Box-Muller
double gaussian_noise (double sigma) {
double u1 = (rand() + 1) / ((double)RAND_MAX + 2);
double u2 = (rand() + 1) / ((double)RAND_MAX + 2);
return sigma * sqrt(-2 * log(u1)) * cos(2 * M_PI * u2);
}
// Ajout du bruit
void add_noise (double complex* s, int len, double sigma) {
//double signal_power = (2.0/3.0)*(qam.M-1);
//double snr_dB = 5; // SNR en dB
//double snr_lin = pow(10.0, snr_dB / 10.0);
//double sigma = sqrt(signal_power / snr_lin);
for (int i = 0; i < len; i++) {
double nr = gaussian_noise(sigma);
double ni = gaussian_noise(sigma);
s[i] += nr + I * ni;
}
}
// Changer le tableau de bits en boolen ou alors la represenation binaire et shifter pour extraire les bits (pas bien si M plus grand)
/*void bits_to_symbols (qam_system* qam, uint8_t* bits, int nb_bits, double complex* symbols) {
int nb_symbols = nb_bits / qam->k;
int sm = sqrt(qam->M);
for (int k = 0; k < nb_symbols; k++) {
int id = 0;
for (int b = 0 ; b < qam->k; b++) {
id = id * 2 + bits[k * qam->k + b];
}
int i = id / sm;
int j = id % sm;
symbols[k] = qam->constellation[i][j];
}
}*/
void bits_to_symbols (qam_system* qam, uint8_t* bits, int nb_bits, double complex* symbols) {
int nb_symbols = nb_bits / qam->k;
int sm = (int)sqrt(qam->M);
// k pair
if (qam->k % 2 != 0) {
printf("bits_to_symbols : k doit être pair (k = %d) \n", qam->k);
exit(1);
}
int bits_per_axis = qam->k / 2;
for (int sym = 0; sym < nb_symbols; sym++) {
// Construire les indices binaires i_bin (MSB...) et j_bin (LSB...)
int i_bin = 0;
int j_bin = 0;
for (int b = 0; b < bits_per_axis; b++) {
i_bin = (i_bin << 1) | bits[sym * qam->k + b];
j_bin = (j_bin << 1) | bits[sym * qam->k + bits_per_axis + b];
}
int i_gray = bin_to_gray(i_bin);
int j_gray = bin_to_gray(j_bin);
if (i_gray < 0 || i_gray >= sm || j_gray < 0 || j_gray >= sm) {
printf("bits_to_symbols : IOOR i_gray = %d j_gray = %d sm = %d \n", i_gray, j_gray, sm);
exit(1);
}
symbols[sym] = qam->constellation[i_gray][j_gray];
}
}
double compare_bits(uint8_t* bits1, uint8_t* bits2, int nb_bits) {
int errors = 0;
for (int i = 0; i < nb_bits; i++) {
if (bits1[i] != bits2[i]) errors++;
}
return (double)errors / nb_bits;
}
void add_dephasage(double complex* s, double phi_offset, int total_samples) {
for (int i = 0; i < total_samples; i++) {
s[i] *= cexp(I * phi_offset);
}
}
void add_freq(qam_system* qam, double complex* s, double freq_offset, int total_samples) {
for (int i = 0; i < total_samples; i++) {
double t = (double)i / qam->Fs;
s[i] *= cexp(I * 2 * M_PI * freq_offset * t);
}
}
void fill_constellation_data(qam_system* qam, FILE *fp_ref) {
int sm = (int)sqrt(qam->M);
for (int i = 0; i < sm; i++) {
for (int j = 0; j < sm; j++) {
fprintf(fp_ref, "% .8f % .8f\n", creal(qam->constellation[i][j]), cimag(qam->constellation[i][j]));
}
}
}
void reconstruction_text(int nb_chars, uint8_t* output_bits, char* texte_recup) {
for(int i = 0; i < nb_chars; i++){
char c = 0;
for(int b = 0; b < 8; b++){
c |= output_bits[i*8 + b] << (7-b);
}
texte_recup[i] = c;
}
texte_recup[nb_chars] = '\0';
}
void text_to_bits(int nb_chars, int nb_bits, char* texte, uint8_t* input_bits) {
for(int i = 0; i < nb_chars; i++){
for(int b = 0; b < 8; b++){
input_bits[i*8 + b] = (texte[i] >> (7-b)) & 1;
}
}
}
@ -129,45 +243,24 @@ void free_constellation(qam_system* qam) {
free(qam->constellation);
}
double compare_bits(uint8_t* bits1, uint8_t* bits2, int nb_bits) {
int errors = 0;
for (int i = 0; i < nb_bits; i++) {
if (bits1[i] != bits2[i]) errors++;
}
return (double)errors / nb_bits;
}
int main () {
// Initialisation du system qam
qam_system qam;
qam.M = 16;
qam.k = (int)log2((double)(qam.M));
qam.Fs = 44100;
//qam.Ts = 0.0003;
//qam.N = (int)qam.Fs * qam.Ts;
qam.Ts = 0.01;
qam.N = (int)(qam.Fs * qam.Ts);
qam.Fc = 2000;
init_constellation(&qam);
//int nb_bits = 1000;
//int nb_symbols = nb_bits / qam.k;
//uint8_t* input_bits = malloc(nb_bits * sizeof(uint8_t));
//for (int i = 0; i < nb_bits; i++) {
// input_bits[i] = rand() % 2;
//}
char* texte = "Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux";
// Conversion du texte en bits
char* texte = "Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux, Vif juge, trempez ce blond whisky aqueux";
int nb_chars = strlen(texte);
int nb_bits = nb_chars * 8;
int nb_symbols = (nb_bits + qam.k - 1) / qam.k;
// Conversion du texte en bits
uint8_t* input_bits = malloc(nb_bits * sizeof(uint8_t));
for(int i = 0; i < nb_chars; i++){
for(int b = 0; b < 8; b++){
input_bits[i*8 + b] = (texte[i] >> (7-b)) & 1;
}
}
text_to_bits(nb_chars, nb_bits, texte, input_bits);
// Conversion en symboles
double complex* symbols = malloc(sizeof(double complex) * nb_symbols);
@ -179,65 +272,28 @@ int main () {
modulate(&qam, symbols, nb_symbols, s);
// Ajout du bruit
double signal_power = (2.0/3.0)*(qam.M-1); // puissance moyenne
double snr_dB = 5; // SNR en dB
double snr_lin = pow(10.0, snr_dB / 10.0);
double sigma = sqrt(signal_power / snr_lin);
add_noise(s, total_samples, 0);
FILE *fp_ref = fopen("constellation_ref.dat", "w");
int sm = (int)sqrt(qam.M);
for (int i = 0; i < sm; i++) {
for (int j = 0; j < sm; j++) {
fprintf(fp_ref, "% .8f % .8f\n", creal(qam.constellation[i][j]), cimag(qam.constellation[i][j]));
}
}
fill_constellation_data(&qam, fp_ref);
fclose(fp_ref);
FILE *fp_constel = fopen("constellation.dat", "w");
// Ajout de dephasage
//double phase_offset = M_PI / 6.0; // 30 degrés
//for (int i = 0; i < total_samples; i++) {
// s[i] *= cexp(I * phase_offset);
//}
//add_dephasage(s, M_PI / 6.0, total_samples);
// AJout de decalage de fréquence
//double freq_offset = 1; // Hz de décalage
//for (int i = 0; i < total_samples; i++) {
// double t = (double)i / qam.Fs;
// s[i] *= cexp(I * 2 * M_PI * freq_offset * t);
//}
// Ajout de decalage entre les symbole
//int offset_samples = (int)(0.3 * qam.N); // décalage de 30% dun symbole
//memmove(s + offset_samples, s, (total_samples - offset_samples) * sizeof(double complex));
//double complex* r_corr = malloc(sizeof(double complex) * total_samples);
//double Kp = 0.2;
//double Ki = 0.02;
//double alpha = 0.1;
//FILE* fp_error = fopen("pll_error.dat", "w");
//pll_qam_symbol(&qam, s, r_corr, nb_symbols, Kp, Ki, alpha, fp_error);
//fclose(fp_error);
//add_freq(&qam, s, 1, total_samples);
// Démodulation
FILE *fp_constel = fopen("constellation.dat", "w");
uint8_t* output_bits = (uint8_t*)malloc(nb_bits * sizeof(uint8_t));
demodulate(&qam, s, nb_symbols, output_bits, fp_constel);
fclose(fp_constel);
// Reconstruction du texte
char* texte_recup = malloc(nb_chars + 1);
for(int i = 0; i < nb_chars; i++){
char c = 0;
for(int b = 0; b < 8; b++){
c |= output_bits[i*8 + b] << (7-b);
}
texte_recup[i] = c;
}
texte_recup[nb_chars] = '\0';
reconstruction_text(nb_chars, output_bits, texte_recup);
printf("Texte original : %s\n\n", texte);
printf("Texte demodulé : %s\n", texte_recup);