Posted By

yuconner on 08/10/06


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filter audio dsp


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yuconner
zdroshnya


Digital low pass filter (first order)


 / Published in: MatLab
 

URL: http://audiores.uint8.com.ar/blog/?p=20

It's a simple low pass filter with comparative graphs.

  1. function [ salida ] = pasabajos(nombre)
  2. %Filtro pasabajos de 1er orden:
  3.  
  4. [X,Fs,bits] = wavread(nombre); %carga el wav
  5. FX = fft(X);
  6. Xmed=mean(X); %debe dar 0
  7. Xvar=var(X);
  8.  
  9. pfiltro = [1 1]; %orden 1, promediador de 2 muestras: y[n]=(x[n]+x[n-1])/2
  10.  
  11. Y=1/2*filter(pfiltro,[1],X);
  12. FY = fft(Y);
  13.  
  14. N=length(FX);
  15. if ( mod(N,2) == 0 )
  16. t=N/2;
  17. else
  18. t=floor(N/2)+1;
  19. end
  20. rectaFrec=linspace(0,pi*Fs/(2*pi),floor(N/2)+1);
  21.  
  22. FX = fftshift(FX);
  23. FY = fftshift(FY);
  24.  
  25. subplot(2,1,1)
  26. title(’Original’)
  27. Espectro=abs(FX(t:N));
  28. plot(rectaFrec,Espectro,’r'); %Grafico en funcion de la frecuencia en Hz
  29.  
  30. subplot(2,1,2)
  31. title(’Pasabajos de 1er orden’)
  32. Espectro=abs(FY(t:N));
  33. plot(rectaFrec,Espectro,’b'); %Grafico en funcion de la frecuencia en Hz
  34.  
  35. salida = Y;

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