[SciPy-User] Signal to noise ratio

Ariel Rokem arokem@berkeley....
Wed Mar 3 20:20:32 CST 2010


Hi Warren,

thanks for this example!

I am getting the following error:

Library/Frameworks/Python.framework/Versions/6.0.0/lib/python2.6/site-packages/scipy/signal/filter_design.py:224:
BadCoefficients: Badly conditionned filter coefficients (numerator): the
results may be meaningless
  "results may be meaningless", BadCoefficients)

For any attempt to filter a low-pass below 12 Hz in this example (so - I
don't get the plot you got - instead I get a flat line on the bottom
subplot). Do you (or anyone?) have any idea why that is?

Cheers,

Ariel

On Wed, Feb 24, 2010 at 7:51 AM, Warren Weckesser <
warren.weckesser@enthought.com> wrote:

> Nils Wagner wrote:
> > Hi all,
> >
> > I have two questions concerning signal processing
> >
> > I have used scipy.stats.signaltonoise to compute the
> > signal-to-noise ratio.
> > The value is 0.0447.
> > How can I judge it ?
> >
> > How can I filter out high frequencies using scipy ?
> >
>
> I posted an example low-pass filtering using 'butter' and 'lfilter' from
> scipy.signal here:
>
>    http://mail.scipy.org/pipermail/scipy-user/2010-January/024032.html
>
> Warren
>
> > How can I eliminate noise from the signal ?
> >
> > Nils
> > _______________________________________________
> > SciPy-User mailing list
> > SciPy-User@scipy.org
> > http://mail.scipy.org/mailman/listinfo/scipy-user
> >
>
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>



-- 
Ariel Rokem
Helen Wills Neuroscience Institute
University of California, Berkeley
http://argentum.ucbso.berkeley.edu/ariel
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