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QAM add constellation plot

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zeefaad
2025-09-30 13:31:59 +02:00
parent 1b1851be8a
commit 821c3ea016
6 changed files with 188 additions and 20 deletions
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QAM/qam
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60
QAM/qam.c
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@ -3,9 +3,11 @@
#include <stdio.h>
#include <stdlib.h>
#include <complex.h>
#include "../WAV/wav.h"
#include "../wav/wav.h"
#include "../files/files.h"
#include "../plot/plot_constellation.h"
#include <string.h>
#include <SDL2/SDL.h>
#define A 10000
@ -73,7 +75,7 @@ void bits_to_symbols (qam_system* qam, uint8_t* bits, int nb_bits, double comple
}
}
// Modulation qam
// Modulation QAM
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];
@ -83,8 +85,8 @@ 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, double sigma) {
// Demodulation QAM
void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bits_hat) {
for (int k = 0; k < nb_symbols; k++) {
double complex r = 0;
for (int n = 0; n < qam->N; n++) {
@ -128,8 +130,21 @@ void demodulate(qam_system* qam, double complex* s, int nb_symbols, uint8_t* bit
}
}
double complex* demodulate_points(qam_system* qam, double complex* s, int nb_symbols) {
double complex* points = malloc(sizeof(double complex) * nb_symbols);
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;
points[k] = r;
}
return points;
}
// Libération de la mémoire
void free_constellation(qam_system *qam) {
void free_constellation(qam_system* qam) {
int sm = (int)sqrt(qam->M);
for (int i = 0; i < sm; i++)
free(qam->constellation[i]);
@ -143,50 +158,46 @@ int main (int argc, char *argv[]) {
}
qam_system qam;
qam.M = 256;
qam.M = 64;
qam.k = (int)log2((double)(qam.M));
qam.Fs = 44100;
qam.Ts = 0.003;
qam.Ts = 0.0003;
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;
printf("Lecture du fichier\n");
printf("Lecture du fichier...\n");
// Lecture du fichier et conversion en bits
const char *input_filename = argv[1];
bit_array input_bits = file_to_bits(input_filename);
size_t nb_symbols = input_bits.nb_bits / qam.k;
printf("Mise en forme des symboles\n");
printf("Mise en forme des symboles...\n");
// Mise en forme des symboles
double complex *symbols = malloc(sizeof(double complex) * nb_symbols);
bits_to_symbols(&qam, input_bits.bits, input_bits.nb_bits, symbols);
printf("Modulation\n");
printf("Modulation...\n");
// Modulation QAM
int total_samples = qam.N * nb_symbols;
double complex* s = (double complex*)malloc(sizeof(double complex) * total_samples);
modulate(&qam, symbols, nb_symbols, s);
// Ajout du bruit
double signal_power = (2.0/3.0)*(qam.M-1); // puissance moyenne avant échelle
double snr_dB = -27; // Signal to noise ratio
double snr_lin = pow(10.0, snr_dB / 10.0);
double sigma = sqrt(signal_power / snr_lin);
printf("Ajout du bruit \n puissance du signal : %f\n SNR db : %f\n sigma : %f\n", signal_power, snr_dB, sigma);
add_noise(s, total_samples, sigma);
printf("Ajout du bruit... \n puissance du signal : %f\n SNR db : %f\n sigma : %f\n", signal_power, snr_dB, sigma);
add_noise(s, total_samples, 1875);
printf("Demodulation\n");
printf("Demodulation...\n");
// Demodulation QAM
bit_array output_bits;
output_bits.nb_bits = input_bits.nb_bits;
output_bits.bits = (uint8_t*)malloc(output_bits.nb_bits);
demodulate(&qam, s, nb_symbols, output_bits.bits, 0.0);
demodulate(&qam, s, nb_symbols, output_bits.bits);
printf("Ecriture...\n");
// Ecriture du fichier de Demodulation
@ -199,9 +210,18 @@ int main (int argc, char *argv[]) {
for (int i = 0; i < total_samples; i++) {
si[i] = cimag(s[i]);
}
write_wav("s.wav", si, total_samples);
write_wav("output.wav", si, total_samples);
// Plot
printf("Ploting...");
plot_t plot;
plot_init(&plot, 1400, 1400, 0.04);
plot_draw_constellation(&plot, qam.constellation, qam.M);
SDL_Color red = {255, 0, 0, 255};
plot_draw_points_animated(&plot, demodulate_points(&qam, s, nb_symbols), nb_symbols, red, 5);
// Libération mémoire
plot_close(&plot);
free_bit_array(&input_bits);
free_bit_array(&output_bits);
free(symbols);

113
plot/plot_constellation.c Normal file
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@ -0,0 +1,113 @@
#include "plot_constellation.h"
#include <stdlib.h>
#include <math.h>
#include <stdio.h>
// Fonction utilitaire pour dessiner un cercle plein
static void draw_filled_circle(SDL_Renderer* renderer, int cx, int cy, int radius) {
for (int w = -radius; w <= radius; w++) {
for (int h = -radius; h <= radius; h++) {
if (w*w + h*h <= radius*radius) {
SDL_RenderDrawPoint(renderer, cx + w, cy + h);
}
}
}
}
// Initialisation SDL
void plot_init(plot_t *plot, int width, int height, double scale) {
if (SDL_Init(SDL_INIT_VIDEO) != 0) {
fprintf(stderr, "Erreur SDL_Init: %s\n", SDL_GetError());
exit(1);
}
plot->width = width;
plot->height = height;
plot->scale = scale;
plot->offset_x = width / 2.0;
plot->offset_y = height / 2.0;
plot->window = SDL_CreateWindow("Constellation QAM", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
width, height, SDL_WINDOW_SHOWN);
if (!plot->window) { fprintf(stderr, "Erreur SDL_CreateWindow: %s\n", SDL_GetError()); exit(1); }
plot->renderer = SDL_CreateRenderer(plot->window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
if (!plot->renderer) { fprintf(stderr, "Erreur SDL_CreateRenderer: %s\n", SDL_GetError()); exit(1); }
SDL_SetRenderDrawColor(plot->renderer, 0, 0, 0, 255); // fond noir
SDL_RenderClear(plot->renderer);
SDL_RenderPresent(plot->renderer);
}
// Dessiner la constellation (grille verte)
void plot_draw_constellation(plot_t *plot, double complex **constellation, int M) {
int sm = (int)sqrt(M);
SDL_SetRenderDrawColor(plot->renderer, 0, 255, 0, 255); // vert
int radius = 8; // gros cercle pour la grille
for (int i = 0; i < sm; i++) {
for (int j = 0; j < sm; j++) {
int x = (int)(creal(constellation[i][j]) * plot->scale + plot->offset_x);
int y = (int)(cimag(constellation[i][j]) * plot->scale + plot->offset_y);
draw_filled_circle(plot->renderer, x, y, radius);
}
}
SDL_RenderPresent(plot->renderer);
}
// Dessiner un tableau de points complexes (rouges)
void plot_draw_points(plot_t *plot, double complex *points, int nb_points, SDL_Color color) {
int radius = 4; // plus petit que la grille verte
SDL_SetRenderDrawColor(plot->renderer, color.r, color.g, color.b, color.a);
for (int k = 0; k < nb_points; k++) {
int x = (int)(creal(points[k]) * plot->scale + plot->offset_x);
int y = (int)(cimag(points[k]) * plot->scale + plot->offset_y);
draw_filled_circle(plot->renderer, x, y, radius);
}
SDL_RenderPresent(plot->renderer);
}
// Dessiner les points progressivement avec animation
void plot_draw_points_animated(plot_t *plot, double complex *points, int nb_points, SDL_Color color, int delay_ms) {
int radius = 4;
int k;
for (k = 0; k < nb_points; k++) {
SDL_SetRenderDrawColor(plot->renderer, color.r, color.g, color.b, color.a);
int x = (int)(creal(points[k]) * plot->scale + plot->offset_x);
int y = (int)(cimag(points[k]) * plot->scale + plot->offset_y);
draw_filled_circle(plot->renderer, x, y, radius);
SDL_RenderPresent(plot->renderer);
// Gestion événements pour stopper animation
SDL_Event event;
int stop = 0;
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) return;
if (event.type == SDL_KEYDOWN) { stop = 1; break; }
}
if (stop) break;
SDL_Delay(delay_ms);
}
// Après animation ou keypress, attendre fermeture ou keypress
int running = 1;
SDL_Event event;
while (running) {
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) running = 0;
if (event.type == SDL_KEYDOWN) running = 0;
}
SDL_Delay(10);
}
}
// Fermer SDL
void plot_close(plot_t *plot) {
SDL_DestroyRenderer(plot->renderer);
SDL_DestroyWindow(plot->window);
SDL_Quit();
}

35
plot/plot_constellation.h Normal file
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@ -0,0 +1,35 @@
#ifndef PLOT_CONSTELLATION_H
#define PLOT_CONSTELLATION_H
#include <complex.h>
#include <SDL2/SDL.h>
typedef struct {
SDL_Window *window;
SDL_Renderer *renderer;
int width;
int height;
double scale;
double offset_x;
double offset_y;
} plot_t;
// Initialiser SDL et la fenêtre
void plot_init(plot_t *plot, int width, int height, double scale);
// Dessiner la constellation (grille de départ)
void plot_draw_constellation(plot_t *plot, double complex **constellation, int M);
// Dessiner un tableau de points complexes
void plot_draw_points(plot_t *plot, double complex *points, int nb_points, SDL_Color color);
// Dessiner les points progressivement avec animation
// delay_ms = délai entre chaque point en millisecondes
// Keypress pendant animation coupe l’animation
void plot_draw_points_animated(plot_t *plot, double complex *points, int nb_points, SDL_Color color, int delay_ms);
// Fermer SDL proprement
void plot_close(plot_t *plot);
#endif

0
WAV/wav.c → wav/wav.c
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0
WAV/wav.h → wav/wav.h
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