MATLAB: Using sinc() in a filter desing

digital signal processingfilterfirsinc

In order to design a filter (windowing method), I first generate my sinc function like so:

L = 20;
fc = 0.25;
n = (1:L)';
my_sinc = sin(2*pi*fc*(n-L/2)) ./ (pi*(n-L/2));            
my_sinc(L/2) = 2*fc;

Then I apply window:

win = blackman(L, 'symmetric');
filter_coeffs = (my_sinc .* win);

Can the first step be done using Matlab builtin sinc()?

Best Answer

This works:

2*fc * sinc(2*fc*(n-L/2))

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MATLAB: Solve a system of equations

function main
x0=zeros(8,1);
sol=fminsearch(@(x)fun(x(1),x(2),x(3),x(4),x(5),x(6),x(7),x(8)),x0)
sol=fminsearch(@(x)fun(x(1),x(2),x(3),x(4),x(5),x(6),x(7),x(8)),sol)
sol=fminsearch(@(x)fun(x(1),x(2),x(3),x(4),x(5),x(6),x(7),x(8)),sol)
sol=fminsearch(@(x)fun(x(1),x(2),x(3),x(4),x(5),x(6),x(7),x(8)),sol)
res=fun(sol(1),sol(2),sol(3),sol(4),sol(5),sol(6),sol(7),sol(8))
end
function res = fun(a1,a2,a3,a4,R1,R2,R3,R4)
l1=50;
l2=50;
l3=50; 
Fc1=30; 
Fc2=50; 
Fc3=100; 
a=25;
b=25;
c=25;
d=25;
e=25;
f=25;
v1=0;
v2=0;
v3=0;
v4=0;
m1=0;
m2=0;
m3=0;
m4=0;
A=[12/l1^2, 6/l1^2, -12/l1^3, 6/l1^2, 0, 0, 0, 0;...
    6/l1^2, 4/l1^2, -6/l1^2, 4/l1^2, 0, 0, 0, 0; ...
    -12/l1^3, -6/l1^2, 12/l1^3+12/l2^3, -6/l1^2+6/l2^2, -12/l2^3, 6/l2^2, 0, 0; ...
    6/l1^2, 2/l1 -6/l1^2+6/l2^2, 4/l1+4/l2, -6/l2^2, 4/l2, 0, 0; ...
    0, 0, -12/l2^3, -6/l2^2, 12/l2^3+12/l3^3, -6/l2^2+6/l3^2, -12/l3^3, 6/l3^2; ...
    0, 0, 6/l2^2, 2/l2, -6/l2^2+6/l3^2, 4/l2+4/l3, -6/l3^2, 4/l3; ...
    0, 0, 0, 0, -12/l3^3, -6/l3^2, 12/l3^3, -6/l3^2; ...
    0, 0, 0, 0, 6/l3^2, 2/l3, -6/l3^2, 4/l3];
x=[v1, a1, v2, a2, v3, a3, v4, a4]';
s=[R1, m1, R2, m2, R3, m3, R4, m4]';
F=[(l1+2*a^3-3*l1*a^2)*Fc1/l1^3, (a^3+l1^2*a-2*l1*a)*Fc1/l1^3, ...
    (2*a^3-3*l1*a^2)*Fc1/l1^2+(l2+2*c^3-3*l2*c^2)*Fc2/l2^3, (a^3-l1*a^2)*Fc1/l1^2+(c^3+l2^2*c-2*l2*c)*Fc2/l2^2, ...
    (2*c^3-3*l2*c^2)*Fc2/l2^2+(l3+2*e^3-3*l3*e)*Fc3/l3^3, (c^3-l2*c^2)*Fc2/l2^2+(e^3+l3*e-2*l3*e)*Fc3/l3^2, ...
    (2*e^3-3*l3*e^2)*Fc3/l3^3, (e^3-l3^2)*Fc3/l3^2]';
res=sum((A*x-s-F).^2);
end

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

Déjà vu

how to design IIR highpass filter with cutoff frequency of 20Hz and FIR bandpass filter with cutoff frequency of 10Hz and 15Hz?

Make the appropriate changes to get the cascaded filter you want.

Best Answer

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MATLAB: Solve a system of equations

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

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