On 3 March 2010 21:20, Ariel Rokem <arokem@berkeley.edu> wrote:

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

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