%program for FIR filters

disp('choose the window from the list');

ch=menu('types of

windows','bartlett','blackman','hamming','hanning','kaiser',

'rectangular');

rp=input('enter the passband ripple in db');

rs=input('enter the stopband ripple in db');

wsample=input('enter sampling frequency in hertz');

wp=input('enter the passband frequency in hertz');

ws=input('enter the stopband frequency in hertz');

wp=2*wp/wsample; ws=2*ws/wsample;

p=20*log10(sqrt(rp*rs))-13;

q=14.6*(ws-wp)/wsample;

N=1+floor(p/q);

N1=N;

if(rem(N,2)==0)

N1=N+1;

else

N=N-1;

end

switch ch

case 1

y=bartlett(N1);

case 2

y=blackman(N1);

case 3

y=hamming(N1);

case 4

y=hanning(N1);

case 5

beta=input('enter beta for kaiser window');

y=kaiser(N1,beta);

case 6

y=boxcar(N1);

otherwise

disp('enter proper window number');

end

disp('select the type of filter from the list');

type=menu('types of

filters','lowpass','highpass','bandpass','bandstop');

switch type

case 1

b=fir1(N,wp,'low',y);

case 2

b=fir1(N,wp,'high',y);

case 3

b=fir1(N,[wp ws],'bandpass',y);

case 4

b=fir1(N,[wp ws],'stop',y);

otherwise

disp('enter type number properly');

end

[h,w]=freqz(b,1,512);

magn=20*log10(abs(h));

phase=(180/pi)*unwrap(angle(h));

w=(w*wsample)/(2*pi);

subplot(2,1,1); plot(w,magn),grid on;title('magnitude

plot'); subplot(2,1,2); plot(w,phase),grid on;title('phase

plot');