Design of a Tunable FIR Filter

[KhaledOsmani]

Hello,

please check the following code:

%Illustration of tunable FIR Filter
clf;
clc;
close all;
w = 0:pi/255:pi;
f = [ 0 0.36 0.46 1];
m = [1 1 0 0];
b1 = remez(50, f, m);
h1 = freqz(b1,1,w);
m1 = 20*log10(abs(h1));
n = -25:-1;
c = b1(1:25)./sin(0.41*pi*n);
wc = ]0.31*pi 0.51*pi];
for i = 1:2
    d = c.*sin(wc(i)*n);
    q = (b1(26)*wc(i))/(0.4*pi);
    b2 = [d q fliplr(d)];
    mag(i,:) = 20*log10(abs(freqz(b2,1,w)));
end
plot (w/pi,mag(1,:) , 'b--', w/pi,m1, 'r-', w/pi, mag(2,:), 'g-');
grid;
axis([ 0 1 -80 5]);
xlabel('\omega/\pi');
ylabel('Gain, dB');
legend ('\omega_{c} = 0.31 \pi','\omega_{c} = 0.41/pi ' , '\omega_{c} = 0.51 \pi')

What type of filter is being designed as the nominal filter by the above code? what are its specifications? what is the order of the filter?
what are the cutoff frequencies of the filters being designed?
How to modify the above code so I can be able to determine and plot the gain response of the delay complementary filter of each of the filters being designed in it?

 

[zorro]

Please see the help of the remez function (doc remez).

Z

 

[KhaledOsmani]

not efficient

 

[KhaledOsmani]

@zorro

any other help please?

 

[FvM]

zorro gave the answer. The complete filter specification is in this three lines:

f = [ 0 0.36 0.46 1];
m = [1 1 0 0];
b1 = remez(50, f, m);

If you are using a recent Matlab version, consider this:

The remez function has been replaced by the new firpm function.

 

[KhaledOsmani]

HOW TO modify it to determine and plot the gain response of the delay complementary filter of each of the filters being designed in it?