[Eeglablist] Filtering issues

[Marianne Løvstad]

Hello

We are currently using Quik-cap 32 channels to record eeg data on a
Neuroscan system. Do anyomne know of a channel location file we can use in
eeglab?

Marianne Løvstad

2012/9/26 Andreas Widmann <widmann at uni-leipzig.de>

> Hi,
>
> googling the list archives (
> http://www.google.com/search?q=highpass+site:sccn.ucsd.edu/pipermail/eeglablist/)
> gives you several threads discussing this problem, e.g.
> http://sccn.ucsd.edu/pipermail/eeglablist/2008/002210.html
>
> In a nutshell: The filter order as suggested by EEGLAB is too high for
> this extreme cutoff-frequency. Use higher cutoff or different filter type.
> Transition band width is defined as cutoff * 0.15 for firls-based filters
> in EEGLAB IIRC.
>
> Note:
> I recommend upgrading to a more recent version of EEGLAB where fir1 is
> used as default filter function (in case you did not select firls
> explicitly). firls-based filtering does not give optimal results (
> http://www.frontiersin.org/Perception_Science/10.3389/fpsyg.2012.00233/full
> ).
>
> Best,
> Andreas
>
> Am 21.09.2012 um 17:03 schrieb tmle at notes.cc.sunysb.edu:
>
> > Hi eeglablist,
> >
> > I have been attempting to apply a highpass filter to our 64-channel data
> set. So far I have only resampled (to 256) and rereferenced (to average
> reference) prior to this step. However, when I enter .01 for the lower edge
> in the basic filter option, eeglab will run for about 20 minutes then give
> me an out of memory error (eeglab error in function firls() at line 150).
> Could you please let me know why this might be the case? I'm not sure
> whether my laptop memory is a problem as it has 8G of RAM. Also, eeglab
> says the eegfilt () - highpass transition band width is 0.001Hz. Shouldn't
> this be .01 like I have entered for the lower edge?
> >
> > Thanks,
> >
> > Le
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-- 


Marianne Løvstad
Psykologspesialist/Ph.d. student
Sunnaas sykehus
tlf: + 47 93 45 20 03
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