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// demonstrate windowing functions
#include <stdio.h>
#include <stdlib.h>
#include "liquid.h"
#define OUTPUT_FILENAME "windowing_example.m"
int main(int argc, char*argv[])
{
// options
liquid_window_type wtype = LIQUID_WINDOW_KAISER;
unsigned int wlen = 51; // window size
float arg = 10.0f; // generic argument
// compute window coefficients
float w[wlen];
unsigned int i;
for (i=0; i<wlen; i++) {
w[i] = liquid_windowf(wtype, i, wlen, arg);
printf("%12.8f\n", w[i]);
}
// export output file
FILE*fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s: auto-generated file\n\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\n");
fprintf(fid,"close all;\n\n");
fprintf(fid,"wlen=%u;\n",wlen);
fprintf(fid,"nfft=%u;\n",1200);
for (i=0; i<wlen; i++)
fprintf(fid,"w(%4u) = %12.4e;\n", i+1, w[i]);
fprintf(fid,"t=0:(wlen-1);\n");
fprintf(fid,"f=[0:(nfft-1)]/nfft-0.5;\n");
fprintf(fid,"figure('position',[50 50 600 800]);\n");
fprintf(fid,"subplot(2,1,1);\n");
fprintf(fid," plot(t,w,'Color',[0 0.25 0.5],'LineWidth',2);\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('Sample Index');\n");
fprintf(fid," ylabel('Window Value');\n");
fprintf(fid," axis([-1 wlen -0.1 1.1]);\n");
fprintf(fid,"subplot(2,1,2);\n");
fprintf(fid," plot(f,20*log10(abs(fftshift(fft(w,nfft)/sum(w)))),'Color',[0 0.5 0.25],'LineWidth',2);\n");
fprintf(fid," grid on;\n");
fprintf(fid," xlabel('Normalized Frequency [f/F_s]');\n");
fprintf(fid," ylabel('PSD [dB]');\n");
fprintf(fid," axis([-0.5 0.5 -140 20]);\n");
fclose(fid);
printf("results written to %s\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
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