Forum: GNU Radio Bandpass spectral correction

558c40b97bd1af8d912424757714bda9?d=identicon&s=25 unknown (Guest)
on 2013-04-08 20:12
(Received via mailing list)
I have a need to have a *very flat* passband for some of the
analysis I'm doing of neutral hydrogen. Real hardware, of course,
produces passbands that aren't quite flat--some worse than others.

So,
I've tried an experiment in one of my flow-graphs where I take the
(aggressively-averaged) FFT magnitudes by taking each bin magnitude and
dividing by the maximum, and then using the inverse of that to produce a
correction curve, as normalized magnitudes.

I then use those
normalized magnitudes in an FFT filter (after converting into
time-domain), and the result works less-well than I would expect. The
result is a *much-flatter* spectrum, but at the fine-scales I'm doing
analysis at (0.5dB), it's not nearly as flat -- the outer edges are
under-corrected, and the inner bits are over-corrected.

Anybody have
any pointers to good papers on passband flattening techniques?
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