FIR Digital Filter Design using Kaiser Window in MATLAB

This section covers MATLAB source code for designing FIR low pass and high pass filters using the Kaiser window method.

FIR Low Pass Filter MATLAB Code

clc;
clear all;
close all;
format long;
rp=input('enter the passband ripple:(default:0.02)');
rs=input('enter the stopband ripple:(default:0.01)');
fp=input('enter the passband frequency:(default:1000)');
fs=input('enter the stopband frequency:(default:1500)');
f=input('enter the sampling frequency:(default:10000)');
beta=input('enter the beta value:(default:5.8)');

wp=2*(fp/f);
ws=2*(fs/f);

num=-20*log10(sqrt(rp*rs))-13;
dem=14.6*(fs-fp)/f;
n=ceil(num/dem);
n1=n+1;

if(rem(n,2)~=0)
    n1=n;
    n=n-1;
end;

y=kaiser(n1,beta);

%Lowpass filter
b=fir1(n,wp,y);
[h,o]=freqz(b,1,256);
m=20*log10(abs(h));

subplot(2,1,1);
plot(o/pi,m);
ylabel('gain in db---->');
xlabel('Normalised frequency---->');
title('FIR filter using Kaiser window of LPF ----');
%grid on;


## FIR High Pass Filter MATLAB Code

```matlab
%Highpass filter
b=fir1(n,wp,'high',y);
[h,o]=freqz(b,1,256);
m=20*log10(abs(h));
subplot(2,1,2);
plot(o/pi,m);
ylabel('gain in db---->');
xlabel('Normalised frequency---->');
title('FIR filter using Kaiser window of HPF ----');
%grid on;

Output Plot