1D constellation + precalculated sqrt(M)

QAM/qam.c

@@ -208,6 +208,32 @@ void free_constellation(qam_system* qam) {
     free(qam->constellation);
 }
 
+// Préambule QAM
+void generate_preamble(qam_system* qam, double complex* preamble, int L) {
+    // L 1er symboles de la constellation
+    for (int i = 0; i < L; i++) {
+        preamble[i] = qam->constellation[i % qam->M];
+    }
+}
+
+// Concatène le préambule avec le signal modulé
+double complex* concat_preamble_signal(double complex* preamble_mod, int preamble_len, double complex* s_mod, int nb_symbols, int N) {
+    int total_samples = (preamble_len + nb_symbols) * N;
+    double complex* s_concat = malloc(sizeof(double complex) * total_samples);
+
+    // Copier le préambule modulé
+    for (int i = 0; i < preamble_len * N; i++) {
+        s_concat[i] = preamble_mod[i];
+    }
+
+    // Copier le signal modulé après le préambule
+    for (int i = 0; i < nb_symbols * N; i++) {
+        s_concat[preamble_len * N + i] = s_mod[i];
+    }
+
+    return s_concat;
+}
+
 int main () {
     // Initialisation du system qam
     qam_system qam;
@@ -232,13 +258,23 @@ int main () {
     double complex* symbols = malloc(sizeof(double complex) * nb_symbols);
     bits_to_symbols(&qam, input_bits, nb_bits, symbols);
 
-    // Modulation
-    int total_samples = qam.N * nb_symbols;
+    // Initialisation du préambule
+    int L = 16;
+    int total_samples = qam.N * (nb_symbols + L);
+
+    double complex* preamble = malloc(sizeof(double complex) * L);
+    generate_preamble(&qam, preamble, L);
+    double complex* preamble_mod = malloc(sizeof(double complex) * L * qam.N);
+    modulate(&qam, preamble, L, preamble_mod);
+
+    double complex* s_mod = malloc(sizeof(double complex) * nb_symbols * qam.N);
+    modulate(&qam, symbols, nb_symbols, s_mod);
+
     double complex* s = malloc(sizeof(double complex) * total_samples);
-    modulate(&qam, symbols, nb_symbols, s);
+    double complex* s_with_preamble = concat_preamble_signal(preamble_mod, L, s_mod, nb_symbols, qam.N);
 
     // Ajout du bruit
-    add_noise(s, total_samples, 0);
+    add_noise(s_with_preamble, total_samples, 0);
 
     FILE *fp_ref = fopen("constellation_ref.dat", "w");
     fill_constellation_data(&qam, fp_ref);
@@ -248,12 +284,12 @@ int main () {
     //add_dephasage(s, M_PI / 6.0, total_samples);
     
     // AJout de decalage de fréquence
-    //add_freq(&qam, s, 1, total_samples); 
+    add_freq(&qam, s_with_preamble, 0, 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);
+    demodulate(&qam, s_mod, nb_symbols, output_bits, fp_constel);
     fclose(fp_constel);
 
     // Reconstruction du texte