92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <complex.h>
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struct qam_system_s {
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int M; // Nombre de symboles M-QAM
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int k; // Nombre de bits/symboles
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double Fs; // Fréquence d'échantillionage
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double Ts; // Temps d'échantillionage
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int N; // Nombre d'échantillions
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double Fc; // Fréquence de la porteuse
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double complex** constellation; // Tableau de symboles I + j Q
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};
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typedef struct qam_system_s qam_system;
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void init_constellation (qam_system *qam) {
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int sm = (int)sqrt(qam->M);
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qam->constellation = (double complex**)malloc(sizeof(double complex*) * sm);
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for (int i = 0; i < sm; i++) {
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qam->constellation[i] = (double complex*)malloc(sizeof(double complex) * sm);
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}
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double norm_factor = sqrt((double)(qam->M - 1) / 3.0); // Pour puissance unitaire
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for (int i = 0; i < sm; i++) {
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double complex ip = -(sm - 1) + 2 * i;
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for (int j = 0; j < sm; j++) {
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double complex qp = -(sm - 1) + 2 * j;
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qam->constellation[i][j] = (ip + I * qp) / norm_factor;
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}
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}
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}
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void free_constellation(qam_system *qam) {
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int sm = (int)sqrt(qam->M);
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for (int i = 0; i < sm; i++)
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free(qam->constellation[i]);
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free(qam->constellation);
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}
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void bits_to_symbols (qam_system *qam, int *bits, int nb_bits, double complex *symbols) {
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int nb_symbols = nb_bits / qam->k;
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int sm = sqrt(qam->M);
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for (int k = 0; k < nb_symbols; k++) {
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int id = 0;
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for (int b = 0 ; b < qam->k; b++) {
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id = id * 2 + bits[k * qam->k + b];
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}
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int i = id / sm;
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int j = id % sm;
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symbols[k] = qam->constellation[i][j];
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}
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}
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void modulate (qam_system *qam,double complex *symbols, int nb_symbols, double complex *s) {
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for (int k = 0; k < nb_symbols; k++) {
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double complex iq = symbols[k];
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for (int n = 0; n < qam->N; n++) {
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s[k * qam->N + n] = iq * cexp(2 * M_PI * qam->Fc * ((double)n / qam->Fs));
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}
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}
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}
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int main () {
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qam_system qam;
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qam.M = 16;
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qam.k = (int)log2((double)(qam.M));
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qam.Fs = 44100;
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qam.Ts = 0.01;
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qam.N = (int)qam.Fs * qam.Ts;
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qam.Fc = 2000;
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init_constellation(&qam);
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// Nombre de bit multiple de k sinon remplir de zero jusqu'a ce que ce le soit
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int bits[16] = {1,0,1,1, 0,1,1,0, 1,1,0,0, 0,0,0,1};
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int nb_symbols = 16 / qam.k;
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double complex symbols[nb_symbols];
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bits_to_symbols(&qam, bits, 16, symbols);
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int total_samples = qam.N * nb_symbols;
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double complex* s = (double complex*)malloc(sizeof(double complex) * total_samples);
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modulate(&qam, symbols, nb_symbols, s);
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free_constellation(&qam);
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free(s);
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return 0;
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}
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