Design of a 4th order digital Chebeyshev type-I filter that passes only the component of 800πt from the signal: x(t)= 2*sin (100πt) + 3*cos (800πt) + sin (1500πt)

MATLAB CODE:

fs=3000;
t=0:1/fs:1;
x=2*sin(100*pi*t)+3*cos(800*pi*t)+sin(1500*pi*t);
X=fft(x);
n=0:1:length(X)-1;
plot(n,abs(X));
figure;
N=4;
f1=300;
f2=500;
Wp1=2*f1/fs;
Wp2=2*f2/fs;
Wp=[Wp1 Wp2];
R=3;
[b,a]=cheby1(N,R,Wp);
zplane(b,a);
freqz(b,a);
y=filter(b,a,x);
Y=fft(y);
figure;

RESULTs:

Input Signal Frequency Components:

Filtered Signal Frequency Components: