QAM completed

QAM/qam.c

@@ -2,6 +2,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <complex.h>
+#include "../WAV/wav.h"
+
+#define A 10000
 
 struct qam_system_s {
     int M; // Nombre de symboles M-QAM
@@ -14,7 +17,7 @@ struct qam_system_s {
 };
 typedef struct qam_system_s qam_system;
 
-void init_constellation (qam_system *qam) {
+void init_constellation (qam_system* qam) {
     int sm = (int)sqrt(qam->M);
     qam->constellation = (double complex**)malloc(sizeof(double complex*) * sm);
     
@@ -28,19 +31,13 @@ void init_constellation (qam_system *qam) {
         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) / norm_factor; 
+            qam->constellation[i][j] = A * (ip + I * qp) / norm_factor; 
         }
     }
 }
 
-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);
-}
-
-void bits_to_symbols (qam_system *qam, int *bits, int nb_bits, double complex *symbols) {
+// 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, 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++) {
@@ -54,38 +51,97 @@ void bits_to_symbols (qam_system *qam, int *bits, int nb_bits, double complex *s
     }
 }
 
-void modulate (qam_system *qam,double complex *symbols, int nb_symbols, double complex *s) {
+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)); 
+            s[k * qam->N + n] = iq * cexp(2 * I * M_PI * qam->Fc * ((double)n / qam->Fs)); 
         }
     }
 }
 
+void demodulate(qam_system* qam, double complex* s, int nb_symbols, int* bits_hat, double sigma) {
+    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
+        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;
+                }
+            }
+        }
+
+        int id = i_cl * sm + j_cl;
+        for (int b = 0; b < qam->k; b++) {
+            bits_hat[k * qam->k + (qam->k - 1 - b)] = (id >> b) & 1;
+        }
+    }
+}
+
+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);
+}
+
 int main () {
     qam_system qam;
-    qam.M = 16;
+    qam.M = 256;
     qam.k = (int)log2((double)(qam.M));
     qam.Fs = 44100;
-    qam.Ts = 0.01;
+    qam.Ts = 0.00003;
     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_bits = 16;
     int nb_symbols = 16 / qam.k;
+
+
     double complex symbols[nb_symbols];
-    bits_to_symbols(&qam, bits, 16, symbols);
+    bits_to_symbols(&qam, bits, nb_bits, 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);
 
+    int bits_hat[nb_bits];
+    demodulate(&qam, s, nb_symbols, bits_hat, 0.0);
+
+    for (int i = 0; i < nb_bits; i++) 
+        printf("%d", bits[i]);
+    printf("\n");
+
+    for (int i = 0; i < nb_bits; i++) 
+        printf("%d", bits_hat[i]);
+    printf("\n");
+
+    double* si = (double*)malloc(sizeof(double) * total_samples);
+
+    for (int i = 0; i < total_samples; i++) {
+       si[i] = cimag(s[i]); 
+    }
+
+    write_wav("s.wav", si, total_samples);
+
     free_constellation(&qam);
     free(s);
+    free(si);
 
     return 0;
 }