<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Mikel,<div><br></div><div>I think Jörn gave you already the answer. You need enough time points to accurately estimate the oscillations of a frequency. For example in wavelet analysis (morlet) people use at least 5 cycles.</div><div><br></div><div>Best,</div><div><br></div><div>Stephan</div><div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div><div>________________________________________________________</div><div>Stephan Moratti, PhD<br><br></div><div>see also: <a href="http://web.me.com/smoratti/">http://web.me.com/smoratti/</a><br><br></div><div>Universidad Complutense de Madrid</div><div>Facultad de Psicología</div><div>Departamento de Psicología Básica I</div><div>Campus de Somosaguas</div><div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain</div><div><br></div><div>and</div><div><br></div><div>Center for Biomedical Technology</div><div>Laboratory for Cognitive and Computational Neuroscience</div><div>Parque Científico y Tecnológico de la Universidad Politecnica de Madrid<br>Campus Montegancedo</div><div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain<br><br><br>email: <a href="mailto:smoratti@psi.ucm.es">smoratti@psi.ucm.es</a><br>Tel.: +34 679219982</div></div></span>
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<br><div><div>El 27/03/2012, a las 12:46, Ion Lavado escribió:</div><br class="Apple-interchange-newline"><blockquote type="cite">Thank you Stephan, just one thing, why i need a time window big enough? so i'm just studying the frequency.<br><br>Best,<br><br>Mikel<br><br><div class="gmail_quote">2012/3/27 Stephan Moratti <span dir="ltr"><<a href="mailto:smoratti@psi.ucm.es">smoratti@psi.ucm.es</a>></span><br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="word-wrap:break-word">Dear Mikel,<div><br></div><div>I understand that you should do a mtmfft with a center frequency of interest (in your case cfg.foil = [11 11]) and then you do a frequency smoothing of 3 Hz (cfg.tapsmofrq = 3). Of course you need a time window big enough to allow such a smoothing. The CSD should represent a frequency window of 8 to 14 Hz then. Then you put the result of the mtmfft into the dics beamformer.</div>
<div><br></div><div>Best,</div><div><br></div><div>Stephan</div><div> <br><div><div>El 27/03/2012, a las 11:19, Ion Lavado escribió:</div><br><blockquote type="cite"><div><div class="h5"><span>Hello, i'm having problems trying the beamformer analysis with a frequency band of interest. I would like to have for example an interval like [8 14] Hz. My concept problem is about the cfg.frequency and cfg.tapsmofrq values. (it must be a escalar, but i want a frequency band). </span><div>
<br></div><div>%FREQ ANALYSIS</div><div><div>cfg = [];</div><div>cfg.method = 'mtmfft';</div><div>cfg.output = 'powandcsd';</div><div>cfg.tapsmofrq = 5;</div><div>cfg.foilim = [8 14];</div>
<div>freq_words_alpha = ft_freqanalysis(cfg, words);</div></div><div><br></div><div><br></div><div>%SOURCE ANALYSIS</div><div><div>cfg = []; </div><div>cfg.frequency = 11; </div><div>
cfg.lambda=0;</div><div>cfg.method = 'dics';</div><div>cfg.coordsys = 'neuromag';</div><div>cfg.projectnoise = 'yes';</div><div>cfg.grad = freq_words_alpha.grad;</div><div>
cfg.channel = {'MEG'}; </div>
<div>cfg.grid = grid; </div><div>cfg.reducerank = 2;</div><div>cfg.vol = vol02;</div><div>vol02=ft_convert_units(vol02,'cm');</div><div>source_pre11 = ft_sourceanalysis(cfg, freq_words_alpha );</div>
</div><div><br></div><div><br></div><div>I use a cfg.frequency of 11 but i don't have really clear what i'm doing as a get the same result using cfg.frequency=11 but a freqanalysis in [10 12]. I would be very grateful if someone could solve my doubt.</div>
<div><br></div><div>Best wishes,</div><div><br></div><div>Mikel</div></div></div>
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<br>________________________________________________________</div><div>Stephan Moratti, PhD<br><br></div><div>see also: <a href="http://web.me.com/smoratti/" target="_blank">http://web.me.com/smoratti/</a><br><br></div><div>
Universidad Complutense de Madrid</div><div>Facultad de Psicología</div><div>Departamento de Psicología Básica I</div><div>Campus de Somosaguas</div><div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain</div><div><br></div>
<div>and</div><div><br></div><div>Center for Biomedical Technology</div><div>Laboratory for Cognitive and Computational Neuroscience</div><div>Parque Científico y Tecnológico de la Universidad Politecnica de Madrid<br>Campus Montegancedo</div>
<div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain<br><br><br>email: <a href="mailto:smoratti@psi.ucm.es" target="_blank">smoratti@psi.ucm.es</a><br>Tel.: <a href="tel:%2B34%20679219982" value="+34679219982" target="_blank">+34 679219982</a><br>
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