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Re: [Discuss-gnuradio] resample ratio for fractional_resampler
From: |
Andy Walls |
Subject: |
Re: [Discuss-gnuradio] resample ratio for fractional_resampler |
Date: |
Tue, 24 Oct 2017 08:16:12 -0400 |
Hi Marcus:
Nice insights and plots.
> From: Marcus Müller
> Date: Mon, 23 Oct 2017 20:10:23 +0200
[snip]
> From the above figure, I'd say: go for 256 taps; 50 dB of anti-
> aliasing should probably suffice.
> On my machine, the 256 tap FIR filter with decimation=64 ran about
> 20% faster than the fractional resampler; comparing what they do to
> white noise, I'd say that whilst the spectral shape of the 256 tap
> FIR is not perfect, the MMSE is pretty much unusable, I guess:
I'd just like to interject here that GNURadio's MMSE filterbank is only
MMSE for input spectral components in the range [-sample_rate/4,
sample_rate/4].
Also it appears that the mmse/fractional_resampler blocks don't perform
any explicit anti-alias filtering. So that's another reason to have a
band-limiting filter out in front of it.
-Andy
- Re: [Discuss-gnuradio] resample ratio for fractional_resampler,
Andy Walls <=