<div>Francesco, </div><div>Have you actually looked at the FFT of the raw data? That will tell you what needs to be removed. You might have line noise at one frequency and monitor noise at a neighboring frequency. </div><div>
Stan<br><br></div><div class="gmail_quote">On Fri, Oct 28, 2011 at 3:15 AM, Roemer van der Meij <span dir="ltr"><<a href="mailto:r.vandermeij@donders.ru.nl">r.vandermeij@donders.ru.nl</a>></span> wrote:<br><blockquote style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;" class="gmail_quote">
<div text="#000000" bgcolor="#FFFFFF">
Hi Francesco,<br>
<br>
Just as a small add to Eelke's reply, you can specify a bs-filter
for several ranges at once by doing it in a matrix, e.g.:<br>
cfg.bsfreq = [58 62; 118 122];<br>
Note though, these filters (at least the standard butterworth) get
increasingly inaccurate (less sharp filter-response, more
'filter-rolling'/edge-artifacts) when going to higher frequencies,
if you are using the same frequency-range-width. <br>
<br>
Best,<br>
Roemer<div><div></div><div class="h5"><br>
<br>
<br>
On 28-10-11 10:36, Eelke Spaak wrote:
<blockquote type="cite">
<pre>Dear Francesco,
A notch filter is referred to as a band-stop filter in
ft_preprocessing's documentation, and is different from the
(regression-based) DFT filter. To use a notch filter, specify:
cfg.bsfilter = 'yes';
cfg.bsfreq = [58 62]; % or whatever you deem appropriate
Note that you will have to apply ft_preprocessing repeatedly if you
explicitly want to filter out the harmonics of the line noise as well.
Best,
Eelke
2011/10/28 Francesco Di Pompeo <a href="mailto:f.dipompeo@unich.it" target="_blank"><f.dipompeo@unich.it></a>:
</pre>
<blockquote type="cite">
<pre>Dear all,
I need a 60 Hz notch filter before the ICA of continuous 4D data.
I did it using ft_preprocessing but the 60 Hz line is still there..
Something wrong in my script?
cfg = [];
cfg.dataset = '0';
cfg.channel = {'MEG', '-A246', '-A170', '-A110', '-A19'};
cfg.bpfilter = 'yes';
cfg.bpfreq = [1 150];
cfg.dftfilter = 'yes';
cfg.dftfreq = [60 120 180];
data_meg = ft_preprocessing(cfg);
-----------------------------------------------------------------
Francesco Di Pompeo, PhD
Institute of Advanced Biomedical Technologies and
Department of Neuroscience and Imaging
University of Chieti "G. d'Annunzio"
Via dei Vestini - Campus Universitario
66013 Chieti - ITALY
ph: <a href="tel:%2B39-0871-3556907" target="_blank" value="+3908713556907">+39-0871-3556907</a>
fax:<a href="tel:%2B39-0871-3556930" target="_blank" value="+3908713556930">+39-0871-3556930</a>
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<br>
</div></div><div>-- <br>
<font size="2"><font color="darkblue"><font face="calibri">Roemer
van der Meij M.Sc.<br>
PhD student<div class="im"><br>
Donders Institute for Brain, Cognition and Behaviour<br></div>
Centre for Cognition<br>
P.O. Box 9104<br>
6500 HE Nijmegen<br>
The Netherlands<br>
Tel: <a href="tel:%2B31%280%2924%203655932" target="_blank" value="+31243655932">+31(0)24 3655932</a><br>
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