Trying to undertsand how MATLAB does resampling, looking at
This is the part where (downsampling) filter coefficients are calculated:
fc = 1/2/pqmax; L = 2*N*pqmax + 1; h = firls( L-1, [0 2*fc 2*fc 1], [1 1 0 0]).*kaiser(L,bta)' ; h = p*h/sum(h);
(In this case
p both represent downsampling ratio.)
Not sure what is the purpose of last line where all filter coefficients are scaled by downsampling ratio over coeffs sum,
p/sum(h)? Does anyone know the theory behind?