<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">Dear Fabio,<div><br></div><div><span style="color:rgb(31,73,125)">> even though I band-pass filter 2-45 Hz, it does not remove the 50Hz.</span><br></div><div><br></div><div>Even if you set your cutoff frequency at 45 Hz, if the transition band width is 20 Hz, it would not suppress 50 Hz very well! Check what EEGLAB filter does--at 45 Hz, it specifies the pass-band edge. I don't know if it guarantees maximum suppression at 50 Hz. Maybe you want to check your filter parameters.</div><div><a href="https://sccn.ucsd.edu/wiki/Firfilt_FAQ">https://sccn.ucsd.edu/wiki/Firfilt_FAQ</a><br></div><div><br></div><div>To suppress line noise,</div><div><ol><li>Apply CleanLine. <a href="https://www.nitrc.org/projects/cleanline/">https://www.nitrc.org/projects/cleanline/</a></li><li>If CleanLine does not work (see <a href="https://sccn.ucsd.edu/wiki/Makoto's_preprocessing_pipeline#Remove_line_noise_using_CleanLine_.2805.2F17.2F2018_Updated.29">https://sccn.ucsd.edu/wiki/Makoto's_preprocessing_pipeline#Remove_line_noise_using_CleanLine_.2805.2F17.2F2018_Updated.29</a>), apply either notch filter at 50 Hz or low-pass filter before 50 Hz.</li></ol><div>Makoto</div></div></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Wed, Dec 5, 2018 at 9:49 AM Fabio Castro <<a href="mailto:Fabio.Castro@brunel.ac.uk">Fabio.Castro@brunel.ac.uk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="color:#1f497d">Hello,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:black"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">I am conducting an experiment where participants imagine a movement, and I am collecting eeg data to analyse the event-related desynchronisation. I had a couple of participants’ data that look a bit weird when
uploaded on EEGLAB. (v. 14.1.1). Data was collected using an ANT eego sport system, and it was recorded online with reference to CPz, but was re-referenced offline to the average of the two mastoid electrodes. Data was uploaded on EEGLAB using the ANT extension
(.cnt format).</span><span style="color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">The data has also been band-pass filtered 2-45 Hz, but the signal looks different from the one I collected. I also checked if the original file had this same problem (the non-re-referenced one), and yes, it has
the same problem. I have uploaded the same file (same extension), in brainstorm, another Matlab toolbox for EEG analysis, and the signal looks completely different.</span><span style="color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">I also have run the power spectrum analysis on both software, and I looks that in EEGLAB, even though I band-pass filter 2-45 Hz, it does not remove the 50Hz. On the contrary, in Brainstorm it does remove it.</span><span style="color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="color:#1f497d">Do you know what may be the problem here, and why the 50 Hz are not removed?</span><span style="color:black"><u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Kind Regards<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">FABIO<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
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