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<pre style="line-height: 17px; white-space: normal; color: rgb(42, 42, 42); background-color: rgb(255, 255, 255);">Hi Jan-Mathijs and David</pre><pre style="line-height: 17px; white-space: normal; color: rgb(42, 42, 42); background-color: rgb(255, 255, 255);"><br></pre><pre style="line-height: 17px; white-space: normal; color: rgb(42, 42, 42); background-color: rgb(255, 255, 255);">Thanks for the reply. I will low-pass filter first and the do the down-sampling.</pre><pre style="line-height: 17px; white-space: normal; color: rgb(42, 42, 42); background-color: rgb(255, 255, 255);">Thanks again!</pre><pre style="line-height: 17px; white-space: normal; color: rgb(42, 42, 42); background-color: rgb(255, 255, 255);"><br></pre><pre style="line-height: 17px; white-space: normal; color: rgb(42, 42, 42); background-color: rgb(255, 255, 255);">Date: Fri, 11 Jan 2013 09:37:35 +0100<br>From: jan-mathijs schoffelen <jan.schoffelen@donders.ru.nl><br>To: FieldTrip discussion list <fieldtrip@science.ru.nl><br>Subject: Re: [FieldTrip] EEG preprocessing<br>Message-ID: <7A5272B6-AC68-44A3-8003-C5AB3F4F4298@donders.ru.nl><br>Content-Type: text/plain; charset="us-ascii"<br><br>Hi Subbu,<br><br>To follow up on David's reply: when you use the ft_resampledata function, the data is also automatically low-passfiltered to avoid aliasing.<br>Highpass filtering is not necessary to avoid aliasing, but in general helps to make the data better behaved at the edges, which avoids ringing of the low-pass filter.<br><br><br><br>Best,<br><br>Jan-Mathijs<br><br>On Jan 11, 2013, at 4:36 AM, David Groppe wrote:<br><br>> You need to low-pass filter the data before downsaple to avoid aliasing.<br>> The matlab function decimate.m can do this for you.<br>> cheers,<br>> -David<br>> <br>> On Thu, Jan 10, 2013 at 3:22 PM, Narayan Iyer <eeguser@hotmail.com> wrote:<br>>> Hi<br>>> <br>>> I have a question on EEG preprocessing. The sampling rate of my 64 channel<br>>> EEG data is 500 Hz and I would like to down-sample this to 256 Hz or 128 Hz.<br>>> My question is, i it advisable to low-pass filter the data first (70 Hz) and<br>>> then down-sample followed by high-pass filter (0.5 Hz) to avoid aliasing<br>>> effect or should I down-sample first and then band-pass filter the data<br>>> (0.5-70 Hz) ? Or does the sequence really matter ?<br>>> I am new to EEG data analysis so this question might be really basic, but<br>>> any help is highly appreciated!<br>>> <br>>> Thanks<br>>> Subbu<br>>> </pre> </div></body>
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