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Re: [Discuss-gnuradio] CIC stop band
From: |
Eng. Firas |
Subject: |
Re: [Discuss-gnuradio] CIC stop band |
Date: |
Thu, 17 May 2007 08:28:39 -0700 (PDT) |
Hello,
I can give you a precise MATLAB based simulated USRP frequency response. All
what I need is the HBF coefficients. So this is an open invitation to our
dear Matt to give us his designed USRP HBF coefficients or frequency
response.
Firas,
Hans Glitsch wrote:
>
> Hello,
>
> Thank you for the graphs. I wasn't aware that there was a HBF after the
> CIC. Yes, I'd like to know the frequency response of the whole usrp from
> input to output when I decimate by 250.
>
> Thank you to everyone for the help so far,
> Hans
> ----- Original Message -----
> From: Firas abbas
> To: Hans Glitsch
> Cc: gnuradio mailing list ; Eric Blossom
> Sent: Wednesday, May 16, 2007 11:19 PM
> Subject: Re: [Discuss-gnuradio] CIC stop band
>
>
> Dear Hans,
>
> I think you meant the frequency response of CIC+ HBF filters. However,
> the USRP CIC decimation filter has 4 stages. I did MATLAB analysis for 4
> stages CIC filter with decimation rate of 250 (as you requested) without
> the HBF. The spectrum analysis result is attached. The first plot is for
> entire range [0 to Fs/2]. The second one is zoomed near the interested
> band. You will see a huge theoretical gain (more than 190 dB) because of
> CIC bit growth.
>
> Firas
>
> Eric Blossom <address@hidden> wrote:
> On Wed, May 16, 2007 at 04:00:24PM -0700, Hans Glitsch wrote:
> > Hello,
> >
> > What is the stop band of the FPGA CIC filter? How do I figure out
> the
> > attenuation at a given frequency outside my bandwidth?
> >
> > I'm decimating by 250.
> >
> > Thanks,
> > Hans
>
> It's a fourth order CIC.
> See http://users.snip.net/~donadio/cic.pdf for the transfer function.
>
> Eric
>
>
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Re: [Discuss-gnuradio] CIC stop band, Robert McGwier, 2007/05/17