Start of QAM

QAM/qam.c

@@ -0,0 +1,85 @@
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <complex.h>
+
+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;
+
+void init_constellation (qam_system *qam) {
+    int sm = 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);
+    }
+
+    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; 
+            qam->constellation[i][j] /= sqrt((qam->M-1)/3.0); // Pour puissance unitaire
+        }
+    }
+}
+
+void bits_to_symbols (qam_system *qam, int *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 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 * M_PI * qam->Fc * ((double)n / qam->Fs)); 
+        }
+    }
+}
+
+int main () {
+    qam_system qam;
+    qam.M = 16;
+    qam.k = (int)log2((double)(qam.M));
+    qam.Fs = 44100;
+    qam.Ts = 0.01;
+    qam.N = (int)qam.Fs * qam.Ts;
+    qam.Fc = 2000;
+    init_constellation(&qam);
+
+    // Nombre de bit multiple de k sinon remplir de zero jusqu'a ce que ce le soit
+    int bits[16] = {1,0,1,1,  0,1,1,0,  1,1,0,0,  0,0,0,1};
+
+    int nb_symbols = 16 / qam.k;
+    double complex symbols[nb_symbols];
+    bits_to_symbols(&qam, bits, 16, symbols);
+
+    int total_samples = qam.N * nb_symbols;
+    double complex* s = (double complex*)malloc(sizeof(double complex) * total_samples);
+    modulate(&qam, symbols, nb_symbols, s);
+
+    for(int i=0; i<sqrt(qam.M); i++) 
+        free(qam.constellation[i]);
+    free(qam.constellation);
+    free(s);
+
+    return 0;
+}