<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 11 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:"Bookman Old Style";
panose-1:2 5 6 4 5 5 5 2 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:purple;
text-decoration:underline;}
p
{mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman";}
span.E-mailStijl18
{mso-style-type:personal-reply;
font-family:"Bookman Old Style";
color:blue;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
@page Section1
{size:595.3pt 841.9pt;
margin:70.85pt 70.85pt 70.85pt 70.85pt;}
div.Section1
{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=NL link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'>Hi Martin,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'>is there a function in fieldtrip which allows to
reconstruct the signal from the powspctrm? <br>
<br>
<font color=blue><span style='color:blue'><o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'>Let
me answer this question, to take away some load from the shoulders of Jan-Mathijs,
whos is becoming the prime signal processing/source reconstruction expert on
this discussion list.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'>The
answer is that such a function does not exist. In fact, what you ask is not
possible. It is possible to reconstruct a signal from a Fourier transform (using
the inverse Fourier transform), but it is not possible to reconstruct a signal
from the squared amplitude of the Fourier transform (which is the power
spectrum – or at least the most common estimate of the power spectrum). In
the power spectrum the phase information is lost, and therefore you cannot
reconstruct the signal.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'>Good
luck,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'>Eric<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Bookman Old Style"><span
lang=EN-GB style='font-size:12.0pt;font-family:"Bookman Old Style";color:blue'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'><br>
</span>Thanks a lot<br>
<br>
best, Martin<o:p></o:p></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>----------------------------------<o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>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.<o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>http://listserv.surfnet.nl/archives/fieldtrip.html<o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>http://www.ru.nl/fcdonders/fieldtrip/<o:p></o:p></span></font></p>
</div>
</div>
</body>
</html>
<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>