[Eeglablist] Notch filter

Tarik S Bel-Bahar tarikbelbahar at gmail.com
Tue Oct 3 23:53:06 PDT 2017

​Greetings, would it be possible for eeglab developers to put in a formal
warning on the GUI option that allows running of this broken old function,
including a link to Andreas' article? Ideally it would be in RED, and have
a "Warning" right within the GUI (not just in the output). If a car had an
airbag that did not work, one should not be able to start the car. One
should not have to crash to find out the airbag doesn't work anymore :)

On Fri, Sep 29, 2017 at 2:45 AM, Andreas Widmann <widmann at uni-leipzig.de>

> Hi Luis,
> > I'm trying to run this code:
> >
> > EEGOUT = pop_eegfilt( EEG, 45, 55, 'revfilt',1);
> >
> > But Matlab shows this error:
> >
> > Filter error: continuous data portion too narrow (DC removed if highpass
> only)
> (1) Do NOT use pop_eegfilt („legacy" in GUI)! it is known to be broken
> since many years. It is deprecated and left for backward compatibility only
> (see https://www.frontiersin.org/articles/10.3389/fpsyg.2012.00233/full
> for more details).
> (2) The syntax is wrong. It should not take string arguments. Correct
> syntax would be pop_eegfilt( EEG, 45, 55, [], 1 );
> (3) The error message suggests that you have very short continuous
> segments (or epoched data?). The error is due to pop_eegfilt using filtfilt
> not accepting segments shorter than 3 times filter order (IIRC).
> However, note that notch filters do show ringing at the signal edges.
> Thus, you should not notch filter short segments or epochs. Even if the
> solution suggested below would run it is not actually recommended to be
> used here.
> > Could anyone tell me which it is the best way to run a Notch filter?
> EEGOUT = pop_eegfiltnew( EEG, 47.5, 52.5, [], 1 );
> Hope this helps! Best,
> Andreas
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