MATLAB Program for FIR Filter

MATLAB Program for FIR:

         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.

ALGORITHM:

LOW PASS FILTER:

Step 1: Read the input sequence
Step 2: Perform low pass filter calculations
Step 3: Plot the output sequences

HIGH PASS FILTER:

Step 1: Read the input sequence
Step 2: Perform high pass filter calculations
Step 3: Plot the output sequences

BAND PASS FILTER:

Step 1: Read the input sequence
Step 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:

                     

















             Fig: FIR window Output

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