110 lines
2.4 KiB
C
110 lines
2.4 KiB
C
#include <stdio.h>
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#include <math.h>
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#include <stdlib.h>
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#include "../WAV/wav.h"
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// Fréquence d'échantillonage
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#define FS 44100
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// Temps d'échantillonage
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#define TS 0.05
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// Nombre d'échantillions
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#define NS (int)(FS*TS)
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// Amplitude du signal
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#define A 22767
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// Fréquence de la porteuse
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#define FC 400
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// Fonction de concaténation deux tableau
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double* concat_tab(double **t, int a, int b) {
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double* tf = malloc(sizeof(double) * a * b);
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int pos = 0;
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for (int i = 0; i < b; i++) {
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for (int j = 0; j < a; j++) {
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tf[pos] = t[i][j];
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pos++;
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}
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}
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return tf;
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}
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// Fontion permetant la modulation d'un bit
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double* modulation_unique(int b) {
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double* s = (double*)malloc(NS * sizeof(double));
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int c = (b == 0) ? A / 2 : A;
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for (int n = 0; n < NS; n++) {
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s[n] = c * cos(2 * M_PI * FC * ((double)n / FS));
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}
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return s;
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}
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// Fonction permetant la modulation d'un suite de bits
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double* modulation(int* b, int nb_symbole) {
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double** s = (double**)malloc(sizeof(double*) * nb_symbole);
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for (int k = 0; k < nb_symbole; k++) {
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s[k] = modulation_unique(b[k]);
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}
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double *sf = concat_tab(s, NS, nb_symbole);
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for (int i = 0; i < nb_symbole; i++) {
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free(s[i]);
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}
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free(s);
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return sf;
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}
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int* askdemodulation(double* r, int nb_symbole) {
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int* sb = (int*)malloc(sizeof(int) * nb_symbole);
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double thr = (A + A / 2.0) / 4.0;
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for (int k = 0; k < nb_symbole; k++) {
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double sum = 0;
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for (int n = 0 ; n < NS; n++) {
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sum += fabs(r[k * NS + n]);
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}
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double avg = sum / NS;
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sb[k] = (avg > thr) ? 1 : 0;
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}
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return sb;
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}
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int main() {
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int bits[] = {0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1,0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1,0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1,0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1};
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int nb_symbole = (sizeof(bits) / sizeof(bits[0])) / 2;
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for (int i = 0; i < 2 * nb_symbole; i++) {
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printf("%d ", bits[i]);
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}
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printf("\n");
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double* sf = modulation(bits, 2 * nb_symbole);
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write_wav("signal.wav", sf, (double)NS * (double)nb_symbole);
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int wav_len;
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double* wav_data = read_wav("signal.wav", &wav_len);
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int* dbits = askdemodulation(wav_data, 2 * nb_symbole);
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for (int i = 0; i < 2 * nb_symbole; i++) {
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printf("%d ", dbits[i]);
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}
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printf("\n");
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free(sf);
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return 0;
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}
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