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Re: [Discuss-gnuradio] MRFM (Magnetic Resonance Force Microsocopy)andGNU
From: |
Jeff Brower |
Subject: |
Re: [Discuss-gnuradio] MRFM (Magnetic Resonance Force Microsocopy)andGNU Radio |
Date: |
Sat, 03 May 2008 13:18:59 -0500 |
Jon-
> > I'm curious .. what do use the 'biquad filters' for? I assume you mean
> > that you've
> > implemented a 4th order IIR filter? If so that would mean somewhat
> > non-linear phase
> > depending on the IIR design type. What type are you using? Elliptic?
> > Other?
>
> The pair of cascaded biquadratic filters form an optimal cantilever
> controller.
> Our experiment software calculates the controller transfer function, a ratio
> of polynomials with four numerator and four denominator coeffcients (floating
> point), using the methods described in the papers linked to our page at
> "Cantilever controller design is discussed _here_ ..."
> Our software refactors and scales that transfer function into two biquad
> filter
> stages with 24-bit integer coefficients. So I guess the filter type is
> "other". Some phase compensation is included in the transfer function,
> as described in the papers.
Ok thanks. A fascinating use of the USRP hardware.
-Jeff