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Altera_Forum's avatar
Altera_Forum
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16 years ago

Output amplitute from an NCO

Am i right in thinking that the output amplitutde from the NCO is not constant over different frequencies?
Altera_Forum's avatar
Altera_Forum
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16 years ago

here is a matlab example of coefficients for inverse sinc 


%inverse sinc filter(31 taps)
n = 31; 
f = linspace(-.5,.5,1024);
A = 1./sinc(f);
h = fftshift(ifft(fftshift(A)));
h = h(513-15:513+15);  %truncate
h = h/sum(h); %normalise

in many cases your interest is in the passband and can improve on it at the expense of stopband