%=========================================================================
%===== The Response of The Filter Shows A Gradual Roll Off.          =====
%===== This Can Be Improved By Increasing The Order of The Filter As =====
%===== Shown Below. This Shows A Much Sharper Cut Off Response.      =====
%=========================================================================

Fs=400;
wn=[0.25];
[b,a]=fir1(200,wn,hamming(201));
[H,w]=freqz(b,a,512);

figure(1);
plot(w*Fs/(2*pi),abs(H));
title('Filter Frequency Response With A Gradual Roll Off');
xlabel('Frequency (Hz)');
ylabel('Magnitude of Frequency Response');
grid on