<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:m="http://schemas.microsoft.com/office/2004/12/omml" 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 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:10.0pt;color:blue'>Marco and list,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:blue'>This linear phase response is proper – the use of this filter will produce the desired effect in the time domain. See an explanation here:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:blue'><a href="http://www.dspguide.com/ch19/4.htm">http://www.dspguide.com/ch19/4.htm</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:blue'>-Jeff Eriksen<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;color:blue'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> eeglablist-bounces@sccn.ucsd.edu [mailto:eeglablist-bounces@sccn.ucsd.edu] <b>On Behalf Of </b>Marco Montalto<br><b>Sent:</b> Thursday, February 21, 2013 7:58 AM<br><b>To:</b> EEGLAB List<br><b>Subject:</b> [Eeglablist] Phase Shift when using EEGLAB Filters<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Dear List,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I have a question to ask regarding filters in EEGLAB. I am using Basic FIR Filter (new) to bandpass filter my data between 0.5 - 30 Hz. I have read in previous posts that all EEGLAB filters are zero-phase filters. Yet the resulting Frequency Response Plot shows that there is a phase shift in the passband. Here is a link to the saved image of the Frequency Response Plot: <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><a href="https://www.dropbox.com/s/uwruvr05np9qxq7/untitled.jpg">https://www.dropbox.com/s/uwruvr05np9qxq7/untitled.jpg</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Would anyone know why this is so i.e. why there is this phase shift? And also ways to overcome this phase shift?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks and looking forward to hearing from you.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Regards,<o:p></o:p></p></div><div><p class=MsoNormal>Marco Montalto<o:p></o:p></p></div></div></body></html>