[Dspforum] Matlab IIR filter outputs

[Ryan Merton]

Hi,

So if I design an IIR filter with FDATool, set it to single-precision
float quantization, and output the coefficients at SOS, I end with
with something curious:

If I have a 10th order filter, I have 5 SOS.  But what I end up with
are 11 sections.  It appears as though some of the section are just
constants though.  I think their only purpose is to apply gain.  I
think I can just multiply the gain into the numerator coefficients and
be left with 5 sets of numerator/denominator coefficients.

Does that make sense?

Thanks,
Ryan