<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Times New Roman; font-size: 12pt; color: #000000'>Hi Davide,<br><br>Nice data (aside from what is indeed probably line noise). I see four approaches you could take, but not sure if it helps. You could just be unlucky with a very fluctuating line noise in this recording (see http://fieldtrip.fcdonders.nl/faq/why_is_there_a_residual_50hz_line-noise_component_after_applying_a_dft_filter). The options I see:<br>- Check if there is actually a datapadding up to 10 s. With already preprocessed data (e.g., after 3rd order gradiometer correction), it is not directly possible to data pad for subsequent dft-filtering. It happened to me not so long ago, that's why I ask. I made a workaround by first creating trials of 10s length, then do the dft-filetering, and after that cut the actual trials out.<br>- If not already done, apply 3rd-order gradiometer correction first (ft_denoise_synthetic, or in the CTF DataEditor)<br>- Use a bandstop-filter instead of the dft<br>- Source-project the data. With my data that usually also gets rid of most line noise (I use LCMV to reconstruct a virtual sensor time course)<br><br>Hope that helps.<br><br>Stan<br><br><hr id="zwchr"><blockquote style="border-left:2px solid rgb(16, 16, 255);margin-left:5px;padding-left:5px;"><b>Van: </b>"Davide Rivolta" <drivolta81@gmail.com><br><b>Aan: </b>"Email discussion list for the FieldTrip project" <fieldtrip@donders.ru.nl><br><b>Verzonden: </b>Maandag 2 juli 2012 18:20:13<br><b>Onderwerp: </b>[FieldTrip] Info about the power-line noise<br><br><div>Dear fieldtrippers,</div>
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<div>I recently run into the attached figures (S01 files). It seems a failure of the power-line noise filter.</div>
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<div>I used the following settings quite succesfully for other subjects:</div>
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<div>cfg.dftfilter = 'yes';</div>
<div>cfg.padding = 10;</div>
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<div>An example of good figures are the "KAT" files. </div>
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<div>These data come from a visual task where people see moving concentrical gratings. Each trial has a different length that range between around 0.5 until 3 seconds.</div>
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<div>Would the bandstop filter be the only possible solution here?</div>
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<div>Thanks,</div>
<div>Davide<br clear="all"></div>
<br>_______________________________________________<br>fieldtrip mailing list<br>fieldtrip@donders.ru.nl<br>http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</blockquote><br><br><br>-- <br><div><span name="x"></span>Stan van Pelt<br><br>Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen<br>Kapittelweg 29, 6525 EN Nijmegen, Netherlands<br>E-mail: stan.vanpelt@donders.ru.nl<br>Website: www.ru.nl/donders/<br>Phone: (+31) (0)24 36 10981<br>Fax: (+31) (0)24 36 10989<span name="x"></span><br></div></div></body></html>