[Eeglablist] what is the difference between eegfilt and eegfiltfft

[Makoto Miyakoshi]

Dear JingShuiShenLiu,

> Is it ok to concatenate the epochs and filter them with highpass of 0.1
Hz,

No, it's not ok. If you want to apply a high-pass filter, go back to the
continuous data and apply it. It's because your filter order tend to be
long (especially if you want to apply 0.1Hz).

Read this page to see why I recommend it.
http://sccn.ucsd.edu/wiki/Firfilt_FAQ

Makoto

On Wed, Feb 11, 2015 at 7:13 PM, 静水深流 <123975520 at qq.com> wrote:

> Thanks, Makoto! Is it ok to concatenate the epochs and filter them with
> highpass of 0.1 Hz, which should allow any filter order to work with
> eegfilt, and to un-concatenate them afterwards?
> ‍
>
> Ya
>
>
> ------------------ 原始邮件 ------------------
> *发件人:* "Makoto Miyakoshi";<mmiyakoshi at ucsd.edu>;
> *发送时间:* 2015年2月12日(星期四) 上午6:30
> *收件人:* "静水深流"<123975520 at qq.com>;
> *抄送:* "eeglablist"<eeglablist at sccn.ucsd.edu>;
> *主题:* Re: [Eeglablist] what is the difference between eegfilt and
> eegfiltfft
>
> Dear QuietWaterDeepFlow,
>
> Do not apply high-pass filter on the epoched data. Always go back to the
> continuous data and apply it. Every filter has time constant (filter order)
> which is like a sliding window. If you have a boundary on your data, the
> filtering process terminates the process before it and resumes after it.
> You don't want to have it happen too many times, because near the boundary
> data are not properly filtered.
>
> Makoto
>
> On Sat, Feb 7, 2015 at 12:19 AM, 静水深流 <123975520 at qq.com> wrote:
>
>> Hi,
>>
>> I encountered a problem when filtering the epoched data (the frame per
>> epoch is 2000 and the sample rate is 500 Hz) with a highpass of 2 Hz. It
>> was ok to use the eegfiltfft(data, 500, 2, []), but was wrong to use the
>> eegfilt(data, 500, 2, []). However, It was ok to use the eegfilt(data,
>> 500, 3, []). I am wondering why cannot filter the data with a highpass
>> of < 3 Hz. Moreover, what the difference between eegfiltfft and eegfilt?
>> Thanks.
>>
>> Regards
>> Ya
>>
>>
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>
>
>
> --
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>



-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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