329 lines
11 KiB
C
329 lines
11 KiB
C
#include <math.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <complex.h>
|
|
#include "../files/files.h"
|
|
#include <string.h>
|
|
|
|
#define A 1
|
|
|
|
struct qam_system_s {
|
|
int M; // Nombre de symboles M-QAM
|
|
int k; // Nombre de bits/symboles
|
|
double Fs; // Fréquence d'échantillionage
|
|
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
|
|
};
|
|
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);
|
|
}
|
|
|
|
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;
|
|
for (int j = 0; j < sm; j++) {
|
|
double complex qp = -(sm - 1) + 2 * j;
|
|
qam->constellation[i][j] = (ip + I * qp);
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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) {
|
|
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];
|
|
}
|
|
}
|
|
|
|
// Modulation QAM
|
|
void modulate (qam_system* qam, double complex* symbols, int nb_symbols, double complex* s) {
|
|
for (int k = 0; k < nb_symbols; k++) {
|
|
double complex iq = symbols[k];
|
|
for (int n = 0; n < qam->N; n++) {
|
|
s[k * qam->N + n] = iq * cexp(2 * I * M_PI * qam->Fc * ((double)n / qam->Fs));
|
|
}
|
|
}
|
|
}
|
|
|
|
// Demodulation QAM
|
|
void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bits_hat) {
|
|
for (int k = 0; k < nb_symbols; k++) {
|
|
double complex r = 0;
|
|
for (int n = 0; n < qam->N; n++) {
|
|
r += s[k * qam->N + n] * cexp(-2 * I * M_PI * qam->Fc * ((double)n / qam->Fs));
|
|
}
|
|
r /= qam->N;
|
|
|
|
// Distance euclidien de Ir et Qr pour avoir le point le plus proche de la constellation (lent)
|
|
int sm = (int)sqrt(qam->M);
|
|
double min_d = INFINITY;
|
|
int i_cl, 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]);
|
|
if (d < min_d) {
|
|
min_d = d;
|
|
i_cl = i;
|
|
j_cl = j;
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Demodulation QAM avec porteuse estimé
|
|
void demodulate2(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bits_hat) {
|
|
for (int k = 0; k < nb_symbols; k++) {
|
|
double complex r = 0;
|
|
for (int n = 0; n < qam->N; n++) {
|
|
r += s[k * qam->N + n];
|
|
}
|
|
r /= qam->N;
|
|
|
|
// Distance euclidien de Ir et Qr pour avoir le point le plus proche de la constellation (lent)
|
|
int sm = (int)sqrt(qam->M);
|
|
double min_d = INFINITY;
|
|
int i_cl, 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]);
|
|
if (d < min_d) {
|
|
min_d = d;
|
|
i_cl = i;
|
|
j_cl = j;
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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;
|
|
}
|
|
}
|
|
}
|
|
/*
|
|
// Pour j = 1 dans la def de wiki sur l'autocorrelation
|
|
double fc_autocorrelation_1_rad(double complex* s, int N) {
|
|
double complex r = 0;
|
|
for (int n = 0; n < N - 1; n++) {
|
|
r += s[n] * conj(s[n + 1]);
|
|
}
|
|
r /= (N - 1);
|
|
double om = -carg(r); // rad / sample
|
|
return om;
|
|
}
|
|
|
|
// Autocorrelation pour trouver la Fc (fréquence de la porteuse)
|
|
double fc_autocorrelation_multilag_rad(double complex* s, int N, int max_lag) {
|
|
double sum_phase = 0;
|
|
for (int k = 1; k <= max_lag; k++) {
|
|
double complex rk = 0;
|
|
for (int n = 0; n < N - k; n++) {
|
|
rk += s[n] * conj(s[n + k]);
|
|
}
|
|
rk /= (double)(N - k);
|
|
sum_phase += -carg(rk) / k;
|
|
}
|
|
return sum_phase / max_lag; // rad/sample
|
|
}
|
|
|
|
// Correction du signal pour enlever l'offset de la porteuse
|
|
void signal_correction(double complex* s, int total_samples, double om_hat) {
|
|
for (int n = 0; n < total_samples; n++) {
|
|
s[n] *= cexp(-I * om_hat * n);
|
|
}
|
|
}
|
|
*/
|
|
|
|
void blind_carrier(double complex* s, int N, int M) {
|
|
int k = (int)sqrt(M); // puissance à élever
|
|
double complex sum = 0;
|
|
for(int n = 0; n < N; n++)
|
|
sum += cpow(s[n], k);
|
|
|
|
double phi_hat = carg(sum) / k;
|
|
|
|
for(int n = 0; n < N; n++)
|
|
s[n] *= cexp(-I * phi_hat);
|
|
}
|
|
|
|
// Libération de la mémoire
|
|
void free_constellation(qam_system* qam) {
|
|
int sm = (int)sqrt(qam->M);
|
|
for (int i = 0; i < sm; i++)
|
|
free(qam->constellation[i]);
|
|
free(qam->constellation);
|
|
}
|
|
|
|
// Compare deux tableaux de bits (0/1) et retourne le pourcentage de fiabilité.
|
|
double taux_erreur_bits(const uint8_t *in_bits, size_t nb_bits_in,
|
|
const uint8_t *out_bits, size_t nb_bits_out) {
|
|
if (!in_bits || !out_bits)
|
|
return 1.0;
|
|
|
|
size_t n_min = nb_bits_in < nb_bits_out ? nb_bits_in : nb_bits_out;
|
|
size_t n_max = nb_bits_in > nb_bits_out ? nb_bits_in : nb_bits_out;
|
|
size_t err = n_max - n_min;
|
|
|
|
for (size_t i = 0; i < n_min; i++)
|
|
err += ((in_bits[i] ^ out_bits[i]) & 1);
|
|
|
|
return n_max ? (double)err / n_max : 0.0;
|
|
}
|
|
|
|
|
|
int main (int argc, char *argv[]) {
|
|
if (argc < 2) {
|
|
fprintf(stderr, "Utilisation: %s <fichier_entree>\n", argv[0]);
|
|
return 1;
|
|
}
|
|
|
|
qam_system qam;
|
|
qam.M = 16;
|
|
qam.k = (int)log2((double)(qam.M));
|
|
qam.Fs = 44100;
|
|
qam.Ts = 0.3;
|
|
qam.N = (int)qam.Fs * qam.Ts;
|
|
qam.Fc = 2000;
|
|
init_constellation(&qam);
|
|
|
|
printf("Lecture du fichier...\n");
|
|
// Lecture du fichier et conversion en bits
|
|
const char *input_filename = argv[1];
|
|
bit_array input_bits = file_to_bits(input_filename);
|
|
size_t nb_symbols = input_bits.nb_bits / qam.k;
|
|
|
|
printf("Mise en forme des symboles...\n");
|
|
// Mise en forme des symboles
|
|
double complex *symbols = malloc(sizeof(double complex) * nb_symbols);
|
|
bits_to_symbols(&qam, input_bits.bits, input_bits.nb_bits, symbols);
|
|
|
|
printf("Modulation...\n");
|
|
// Modulation QAM
|
|
int total_samples = qam.N * nb_symbols;
|
|
double complex* s = (double complex*)malloc(sizeof(double complex) * total_samples);
|
|
modulate(&qam, symbols, nb_symbols, s);
|
|
|
|
// Ajout du bruit
|
|
double signal_power = (2.0/3.0)*(qam.M-1); // puissance moyenne avant échelle
|
|
double snr_dB = 10; // Signal to noise ratio
|
|
double snr_lin = pow(10.0, snr_dB / 10.0);
|
|
double sigma = sqrt(signal_power / snr_lin);
|
|
printf("Ajout du bruit... \n puissance du signal : %f\n SNR db : %f\n sigma : %f\n", signal_power, snr_dB, sigma);
|
|
add_noise(s, total_samples, 0);
|
|
|
|
|
|
// Demodulation QAM
|
|
//printf("Demodulation...\n");
|
|
//bit_array output_bits;
|
|
//output_bits.nb_bits = input_bits.nb_bits;
|
|
//output_bits.bits = (uint8_t*)malloc(output_bits.nb_bits * sizeof(uint8_t));
|
|
//demodulate(&qam, s, nb_symbols, output_bits.bits);
|
|
|
|
//printf("Ecriture...\n");
|
|
// Ecriture du fichier de Demodulation
|
|
//char *output_filename = make_output_filename(input_filename);
|
|
//bits_to_file(output_filename, &output_bits);
|
|
|
|
//double erreurs = taux_erreur_bits(input_bits.bits, input_bits.nb_bits, output_bits.bits, output_bits.nb_bits);
|
|
|
|
//printf("Comparaison :\n");
|
|
//printf(" Erreurs : %f\n", erreurs * 100);
|
|
|
|
/*
|
|
double om_hat = fc_autocorrelation_1_rad(s, total_samples);
|
|
printf("Estimation de fc 1: %f\n", (om_hat * qam.Fs) / (2 * M_PI));
|
|
|
|
om_hat = fc_autocorrelation_multilag_rad(s, total_samples, 10);
|
|
printf("Estimation de fc multilag: %f\n", (om_hat * qam.Fs) / (2 * M_PI));
|
|
|
|
// Correction du signal avec Fc (en rad/sample) trouvé
|
|
signal_correction(s, total_samples, om_hat);
|
|
|
|
printf("Demodulation...\n");
|
|
demodulate2(&qam, s, nb_symbols, output_bits.bits);
|
|
*/
|
|
|
|
// Avant la demodulation
|
|
printf("Test de blind carrier correction...\n");
|
|
|
|
// Paramètres CMA simples
|
|
double mu = 0.001; // pas d'adaptation
|
|
int num_iter = 100; // nombre d'itérations
|
|
|
|
// Appel de la fonction blind carrier correction
|
|
blind_carrier(s, total_samples, qam.M);
|
|
|
|
// Ensuite, utilise ton démodulateur actuel
|
|
bit_array output_bits;
|
|
output_bits.nb_bits = input_bits.nb_bits;
|
|
output_bits.bits = (uint8_t*)malloc(output_bits.nb_bits * sizeof(uint8_t));
|
|
|
|
demodulate2(&qam, s, nb_symbols, output_bits.bits);
|
|
|
|
// Comparaison avec bits originaux
|
|
double erreurs = taux_erreur_bits(input_bits.bits, input_bits.nb_bits, output_bits.bits, output_bits.nb_bits);
|
|
printf("Taux d'erreur après blind carrier correction: %f %%\n", erreurs * 100);
|
|
|
|
// Ecriture du fichier de Demodulation
|
|
printf("Ecriture...\n");
|
|
char *output_filename = make_output_filename(input_filename);
|
|
bits_to_file(output_filename, &output_bits);
|
|
|
|
// Libération mémoire
|
|
free_bit_array(&input_bits);
|
|
free_bit_array(&output_bits);
|
|
free(symbols);
|
|
free(s);
|
|
free_constellation(&qam);
|
|
free(output_filename);
|
|
|
|
return 0;
|
|
}
|