[Eeglablist] phase shift-free Butterworth filter

[Ronald Phlypo]

Dear Jutta,

the most straightforward way to implement phase shift-free filtering is 
to use a symmetric (non-causal or time-shift) filter, this can be 
obtained through the matlab function "filtfilt" which uses the same 
arguments as the regular "filter" function. Though, you need to be aware 
that this function doubles the filter order (one regular filtering and 
one time-reversed filtering is needed to construct the symmetry) and 
that the filter is no longer causal (due to the time reversal).

Hope this helps,

Ronald

Le 29/03/2012 02:37, Jutta Stahl a écrit :
> Hi EEGlablist,
>
> I want to use a phase shift-free Butterworth filter in EEGlab. Can
> anyone recommend the appropriate function in EEGLAB?
>
> Thanks, Jutta
>
>
>
>
>
> Jutta Stahl
> Differentielle Psychologie und Psychologische Diagnostik
> Höninger Weg 115, 50969 Köln, Raum: 2.02
> Telefon: 0221 470-6289
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> http://www.hf.uni-koeln.de/33398
>
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