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<p class=MsoNormal><span style='font-size:12.0pt;line-height:115%;font-family:
"Cambria","serif"'>Dear all,<o:p></o:p></span></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Cambria","serif"'>I
am a beginner on MEG and I have some basic questions on Fourier transformation
using the function </span><span style='font-size:12.0pt;font-family:"Cambria","serif";
color:black'>freqanalysis_mtmfft</span><span style='font-size:12.0pt;
font-family:"Cambria","serif"'>. It would be great if you could help me!<o:p></o:p></span></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Cambria","serif"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;line-height:115%;font-family:
"Cambria","serif"'>We are interested in Steady State Responses. Therefore we
recorded data 60 seconds trials. <o:p></o:p></span></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Cambria","serif"'>To
transform the time domain into a frequency spectrum we used the function </span><span
style='font-size:12.0pt;font-family:"Cambria","serif";color:black'>freqanalysis_mtmfft.
However, I am not sure which </span><span style='font-size:12.0pt;font-family:
"Cambria","serif"'>value </span><span style='font-size:10.0pt;font-family:"Courier New"'>cfg.tapsmofrq</span><span
style='font-size:12.0pt;font-family:"Cambria","serif"'>. 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></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Cambria","serif"'><o:p> </o:p></span></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Cambria","serif"'>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></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Cambria","serif"'><o:p> </o:p></span></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Cambria","serif"'>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></p>
<p class=MsoNormal style='margin-bottom:0in;margin-bottom:.0001pt;line-height:
normal;text-autospace:none'><span style='font-size:12.0pt;font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;line-height:115%;font-family:
"Cambria","serif"'>Thanks a lot in advance for your help,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;line-height:115%;font-family:
"Cambria","serif"'> Anette<o:p></o:p></span></p>
<p class=MsoNormal><o:p> </o:p></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>