AIM:
To write a program for FIR(Finite Impulse Response) filter like Low pass FIR filter, High pass FIR filter, Band pass FIR filter and Band stop FIR filter using Rectangular window using MATLAB in IT1254 - DSP and Communications Systems Lab.ALGORITHM:
LOW PASS FILTER:
Step 1: Read the input sequenceStep 2: Perform low pass filter calculations
Step 3: Plot the output sequences
HIGH PASS FILTER:
Step 1: Read the input sequenceStep 2: Perform high pass filter calculations
Step 3: Plot the output sequences
BAND PASS FILTER:
Step 1: Read the input sequenceStep 2: Perform band pass filter calculations
Step 3: Plot the output sequences
BAND STOP FILTER:
Step 1: Read the input sequence Step 2: Perform band stop filter calculations
Step 3: Plot the output sequences
PROGRAM:
clc;
clear all;
close all;
rp=input('Enter the passband ripple(rp):');
rs=input('Enter the stopband ripple(rs):');
fp=input('Enter the passband frequency(fp):');
fs=input('Enter the stopband
frequency(fs):');
f=input('Enter the sampling frequency(f):');
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=boxcar(n1);
%Low pass filter
b=fir1(n,wp,y);
[h,o]=freqz(b,1,256);
m=20*log10(abs(h));
subplot(2,2,1);
plot(m);
ylabel('Gain(db)->');
xlabel('(a)Normalised frequency->');
%High pass filter
b=fir1(n,wp,'high',y);
[h,o]=freqz(b,1,256);
m=20*log10(abs(h));
subplot(2,2,2);
plot(m);
ylabel('Gain(db)->');
xlabel('(b)Normalised frequency->');
%Band pass filter
wn=[wp*ws];
b=fir1(n,wn,y);
[h,o]=freqz(b,1,256);
m=20*log10(abs(h));
subplot(2,2,3);
plot(m);
ylabel('Gain(db)->');
xlabel('(c)Normalised frequency->');
%Band stop filter
wn=[wp*ws];
b=fir1(n,wn,'stop',y);
[h,o]=freqz(b,1,256);
m=20*log10(abs(h));
subplot(2,2,4);
plot(m);
ylabel('Gain(db)->');
xlabel('(d)Normalised frequency->');
OUTPUT:
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RESULT:
Thus the program for FIR Filter using Rectangular window was performed using MATLAB and the output sequences were drawn.
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