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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;line-height:115%;font-family:Arial;color:navy'>Dear Anette,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;line-height:115%;font-family:Arial;color:navy'>Cfg.tapsmofrq is an
option for multitaper analysis (cfg.taper = ‘dpss’), which might
not be what you want if you want high frequency resolution. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;line-height:115%;font-family:Arial;color:navy'>I would recommend looking
at the tutorial “Time-frequency analysis using Hanning window,
multitapers and wavelets” <a
href="http://fieldtrip.fcdonders.nl/tutorial/timefrequencyanalysis">http://fieldtrip.fcdonders.nl/tutorial/timefrequencyanalysis</a>
there you can read about the differences between hanning taper and multitapers.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;line-height:115%;font-family:Arial;color:navy'>Hope this helps a bit<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;line-height:115%;font-family:Arial;color:navy'>Best Ingrid<o:p></o:p></span></font></p>
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<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal'><b><font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:
Tahoma;font-weight:bold'>From:</span></font></b><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'> FieldTrip discussion list
[mailto:FIELDTRIP@NIC.SURFNET.NL] <b><span style='font-weight:bold'>On Behalf
Of </span></b>Anette Giani<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, December 17, 2009
9:48 AM<br>
<b><span style='font-weight:bold'>To:</span></b> FIELDTRIP@NIC.SURFNET.NL<br>
<b><span style='font-weight:bold'>Subject:</span></b> [FIELDTRIP] A newbie's
question on Fourier using freqanalysis_mtmfft</span></font><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt;
line-height:115%'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Cambria><span style='font-size:12.0pt;
line-height:115%;font-family:Cambria'>Dear all,<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face=Cambria><span style='font-size:
12.0pt;font-family:Cambria'>I am a beginner on MEG and I have some basic
questions on Fourier transformation using the function <font color=black><span
style='color:black'>freqanalysis_mtmfft</span></font>. It would be great if you
could help me!<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face=Cambria><span style='font-size:
12.0pt;font-family:Cambria'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Cambria><span style='font-size:12.0pt;
line-height:115%;font-family:Cambria'>We are interested in Steady State
Responses. Therefore we recorded data 60 seconds trials. <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face=Cambria><span style='font-size:
12.0pt;font-family:Cambria'>To transform the time domain into a frequency
spectrum we used the function <font color=black><span style='color:black'>freqanalysis_mtmfft.
However, I am not sure which </span></font>value </span></font><font size=2
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>cfg.tapsmofrq</span></font><font
size=3 face=Cambria><span style='font-size:12.0pt;font-family:Cambria'>. Since
we would like to have the highest frequency resolution possible I set
cfg.tapsmofrq to 0.25; the lowest value possible. Do you think that was a good
choice? Further, does this value mean that our lowest possible frequency
resolution would be 0.25? If that was the case, how could I avoid all
smoothing?<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face=Cambria><span style='font-size:
12.0pt;font-family:Cambria'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face=Cambria><span style='font-size:
12.0pt;font-family:Cambria'>Second, do you think that it would be useful to pad
the signal with zeros to artificially increase the frequency resolution? I
guess this could be done using cfg.pad?<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face=Cambria><span style='font-size:
12.0pt;font-family:Cambria'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face=Cambria><span style='font-size:
12.0pt;font-family:Cambria'>Lastly, an even more general question: What do you
think would be handier: (1) Compute the frequency spectrum over 60 seconds, to
get a high frequency resolution or (2) to cut the signal into e.g. 4 second
pieces and to average all spectra to increase the signal to noise ratio?<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><font size=3 face="Courier New"><span
style='font-size:12.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Cambria><span style='font-size:12.0pt;
line-height:115%;font-family:Cambria'>Thanks a lot in advance for your help,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Cambria><span style='font-size:12.0pt;
line-height:115%;font-family:Cambria'> Anette<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt;
line-height:115%'><o:p> </o:p></span></font></p>
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<p>----------------------------------</p>
<p>The aim of this list is to facilitate the discussion between users of the FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis.</p>
<p> http://listserv.surfnet.nl/archives/fieldtrip.html</p>
<p> http://www.ru.nl/fcdonders/fieldtrip/</p>
<p>----------------------------------</p>
<p>The aim of this list is to facilitate the discussion between users of the FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis.</p>
<p> http://listserv.surfnet.nl/archives/fieldtrip.html</p>
<p> http://www.ru.nl/fcdonders/fieldtrip/</p>