BUTTERWORTH HIGH PASS FILTER MATLAB PROGRAM

BUTTERWORTH HIGH PASS FILTER

 

 

alphap=.4;    %Passband attenuation in db

alphas=30;    %stopband attenuation in db

fs=400;    %stopband frequency in hz

fp=800;    %passband frequency in hz

F=2000;

omp=2*fp/F;oms=2*fs/F;

%To find cutoff frequency and order of the filter

[n,wn]=buttord(omp,oms,alphap,alphas);

%system function of the filter

[b,a]=butter(n,wn,'high');

w=0:.01:pi;

[h,om]=freqz(b,a,w);

m=20*log(abs(h));

an=angle(h);

subplot(2,1,1);

plot(om/pi,m);

grid;

ylabel('Gain in db');

xlabel('Normalised frequency');

subplot(2,1,2);

plot(om/pi,an);

grid;

ylabel('Phase in radians');

xlabel('Normalised frequency');