qam edits

QAM/constellation_ref.dat

@@ -0,0 +1,16 @@
+-3.00000000 -3.00000000
+-3.00000000 -1.00000000
+-3.00000000  1.00000000
+-3.00000000  3.00000000
+-1.00000000 -3.00000000
+-1.00000000 -1.00000000
+-1.00000000  1.00000000
+-1.00000000  3.00000000
+ 1.00000000 -3.00000000
+ 1.00000000 -1.00000000
+ 1.00000000  1.00000000
+ 1.00000000  3.00000000
+ 3.00000000 -3.00000000
+ 3.00000000 -1.00000000
+ 3.00000000  1.00000000
+ 3.00000000  3.00000000

QAM/plot_const.plt

@@ -0,0 +1,16 @@
+set terminal qt size 600,600 title "Diagramme de constellation"
+set xlabel "I (In-phase)"
+set ylabel "Q (Quadrature)"
+set grid
+set key off
+set pointsize 1.5
+set xrange [-5:5]
+set yrange [-5:5]
+
+while (1) {
+    plot \
+        'constellation_ref.dat' using 1:2 with points pt 7 ps 2.5 lc rgb "yellow", \
+        'constellation.dat' using 1:2 with points pt 7 ps 1 lc rgb "blue"
+    pause 0.15
+}
+

QAM/qam.c

@@ -4,8 +4,9 @@
 #include <stdlib.h>
 #include <complex.h>
 #include <string.h>
+#include "../wav/wav.h"
 
-#define A 1 
+#define A 3000
 
 struct qam_system_s {
     int M; // Nombre de symboles M-QAM
@@ -82,7 +83,7 @@ void modulate (qam_system* qam, double complex* symbols, int nb_symbols, double
 }
 
 // Demodulation QAM 
-void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bits_hat) {
+void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bits_hat, FILE *fp_constel) {
     for (int k = 0; k < nb_symbols; k++) {
         double complex r = 0;
         for (int n = 0; n < qam->N; n++) {
@@ -90,8 +91,12 @@ void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bit
         }
         r /= qam->N;
 
-        // Distance euclidien de Ir et Qr pour avoir le point le plus proche de la constellation (lent)
+        if (fp_constel) {
+            fprintf(fp_constel, "% .8f % .8f\n", creal(r), cimag(r));
+            fflush(fp_constel); 
+        }
 
+        // 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;
@@ -106,7 +111,7 @@ void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bit
             }
         }
 
-                // index du symbole (id) : même mappage que dans bits_to_symbols()
+        // 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++) {
@@ -131,37 +136,12 @@ double compare_bits(uint8_t* bits1, uint8_t* bits2, int nb_bits) {
     return (double)errors / nb_bits;
 }
 
-void symbol_timing_recovery(double complex* r, int r_len, double complex* preamble, int preamble_len, int N_max, int* offset_est, int* N_est) {
-    double max_corr = 0;
-    int best_offset = 0;
-    int best_N = 1;
-
-    for(int N_try = 1; N_try <= N_max; N_try++) {
-        for(int off = 0; off <= r_len - preamble_len * N_try; off++) {
-            double complex corr = 0;
-            for(int k = 0; k < preamble_len; k++) {
-                for(int n = 0; n < N_try; n++) {
-                    corr += r[off + k * N_try + n] * conj(preamble[k]);
-                }
-            }
-            double mag = cabs(corr);
-            if(mag > max_corr) {
-                max_corr = mag;
-                best_offset = off;
-                best_N = N_try;
-            }
-        }
-    }
-
-    *offset_est = best_offset;
-    *N_est = best_N;
-}
 int main () {
     qam_system qam;
     qam.M = 16;
     qam.k = (int)log2((double)(qam.M));
     qam.Fs = 44100;
-    qam.Ts = 0.0003;
+    qam.Ts = 0.05;
     qam.N = (int)qam.Fs * qam.Ts;
     qam.Fc = 2000;
     init_constellation(&qam);
@@ -173,7 +153,7 @@ int main () {
     //for (int i = 0; i < nb_bits; i++) {
     //    input_bits[i] = rand() % 2;
     //}
-    char* texte = "Bonjour tout le monde salut !!";  
+    char* texte = "Test du test";  
     int nb_chars = strlen(texte);
     int nb_bits = nb_chars * 8;
     int nb_symbols = (nb_bits + qam.k - 1) / qam.k;
@@ -200,53 +180,27 @@ int main () {
     double snr_dB = 5; // SNR en dB
     double snr_lin = pow(10.0, snr_dB / 10.0);
     double sigma = sqrt(signal_power / snr_lin);
-    add_noise(s, total_samples, 0);
+    add_noise(s, total_samples, sigma + 3);
+
+
+    FILE *fp_ref = fopen("constellation_ref.dat", "w");
+    int sm = (int)sqrt(qam.M);
+    for (int i = 0; i < sm; i++) {
+        for (int j = 0; j < sm; j++) {
+            fprintf(fp_ref, "% .8f % .8f\n",
+                    creal(qam.constellation[i][j]),
+                    cimag(qam.constellation[i][j]));
+        }
+    }
+    fclose(fp_ref);
+    FILE *fp_constel = fopen("constellation.dat", "w");
 
     // Démodulation
-    //uint8_t* output_bits = malloc(nb_bits * sizeof(uint8_t));
-    //demodulate(&qam, s, nb_symbols, output_bits);
+    uint8_t* output_bits = malloc(nb_bits * sizeof(uint8_t));
+    demodulate(&qam, s, nb_symbols, output_bits, fp_constel);
 
-    // Calcul du taux d'erreur
-    //double ber = compare_bits(input_bits, output_bits, nb_bits);
-    //printf("Taux d'erreur : %.4f\n", ber *  100);
+    fclose(fp_constel);
 
-    // Blind QAM
-    int preamble_symbols = 32;
-    uint8_t* preamble_bits = malloc(preamble_symbols * qam.k * sizeof(uint8_t));
-    // Genere un préambule aléatoire
-    for(int i = 0; i < preamble_symbols * qam.k; i++) {
-        preamble_bits[i] = rand() % 2;
-    }
-    double complex* preamble_symbols_complex = (double complex*)malloc(sizeof(double complex) * preamble_symbols);
-    bits_to_symbols(&qam, preamble_bits, preamble_symbols * qam.k, preamble_symbols_complex);
-    // Ajout du préambule dans les données
-    int total_symbols = preamble_symbols + nb_symbols;
-    double complex* all_symbols = malloc(sizeof(double complex) * total_symbols);
-    // Copier le préambule
-    for(int i = 0; i < preamble_symbols; i++) {
-        all_symbols[i] = preamble_symbols_complex[i];
-    }
-    // Copier les symboles réels
-    for(int i = 0; i < nb_symbols; i++) {
-        all_symbols[i + preamble_symbols] = symbols[i];
-    }
-    int total_samples_with_preamble = total_symbols * qam.N;
-    double complex* s_with_preamble = malloc(sizeof(double complex) * total_samples_with_preamble);
-
-    modulate(&qam, all_symbols, total_symbols, s_with_preamble);
-
-
-    // Symbol Timing Recovery blind 
-    int offset_est = 0;
-    int N_est = 0;
-    symbol_timing_recovery(s_with_preamble, total_samples_with_preamble, preamble_symbols_complex, preamble_symbols, qam.N*2, &offset_est, &N_est);
-
-    printf("Symbol Timing Recovery : offset=%d, N_est=%d (%d)\n", offset_est, N_est, qam.N);
-
-    /*
-    // Calcul du BER
-    double ber = compare_bits(input_bits, output_bits, nb_bits);
-    printf("Taux d'erreur blind QAM: %.4f\n", ber * 100);
 
     // Reconstruction du texte
     char* texte_recup = malloc(nb_chars + 1);
@@ -260,11 +214,22 @@ int main () {
     texte_recup[nb_chars] = '\0';
     printf("Texte original : %s\n", texte);
     printf("Texte demodulé : %s\n", texte_recup);
-    */
+
+    // Calcul du BER
+    double ber = compare_bits(input_bits, output_bits, nb_bits);
+    printf("Taux d'erreur blind QAM: %.4f\n", ber * 100);
+
+    // Affichage du signal dans un .wav
+    double* si = (double*)malloc(sizeof(double) * total_samples);
+    for (int i = 0; i < total_samples; i++) {
+       si[i] = cimag(s[i]); 
+    }
+    write_wav("output.wav", si, total_samples);
+
 
     // Libération mémoire
     free(input_bits);
-    //free(output_bits);
+    free(output_bits);
     free(symbols);
     free(s);
     free_constellation(&qam);