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Re: Xlating FIR filter delay
From: |
CEL |
Subject: |
Re: Xlating FIR filter delay |
Date: |
Thu, 19 Dec 2019 14:31:42 +0000 |
Ah, no!
So, what you're seeing is no processing delay caused by our
implementation of the xlating FIR filter, but simply *group delay*,
which every linear system has.
I don't know your background, so it's a bit hard to recommend some
literature, but group delay would be covered in a "signals and systems"
text book.
> Guess I've found the answer:
> (len(filter_taps) - 1) / 2
That is true ONLY if your filter has linear phase. It has linear phase
iff it's symmetric to the center tap.
Best regards,
Marcus
On Thu, 2019-12-19 at 14:08 +0000, Angilberto Muniz Sb wrote:
> Yes Marcus, I'm interested in the "excess" delay, thats why I need to cancel
> the group delay.
>
> Guess I've found the answer:
>
> (len(filter_taps) - 1) / 2
>
> Will try it..
>
>
> Angilberto.
>
>
> Em quinta-feira, dezembro 19, 2019, 9:16 AM, Müller, Marcus (CEL)
> <address@hidden> escreveu:
>
> > Hi Angilberto,
> >
> > am I right to assume that you already are considering the group delay
> > of the filter that you specified and there's "excess" delay beyond
> > that?
> >
> > Best regards,
> > Marcus
> >
> > On Wed, 2019-12-18 at 19:59 +0000, Angilberto Muniz Sb wrote:
> > > Hi all,
> > >
> > > I have a dual tone signal that I down convert and split into two common
> > > frequency signals with the Xlating-fir filter. So far so good.
> > >
> > > However I noticed there is a phase shift between the signals generated (I
> > > assume this is due the filter delay). I have to compensate for that.
> > >
> > > The question: How to determine or estimate that delay?
> > >
> > > Thank you,
> > >
> > >
> > > Angilberto.
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