[Eeglablist] Exporting continuous EEG data from BESA to EEGLAB

[Chang Gu]

Hi Arno,

We found our problem of transferring data between EEGLAB and BESA:
Before, we installed the EEGLAB under Mac OX, and BESA is under Window. Once
we switch to EEGLAB under Window to read data from BESA, there's no problem
exporting and importing. Something different in writing data between 2
operating system...

But I still have a question:

Is there a plugin of EEGLAB for reading event information (.evt file)
exported from BESA? In following format: Tmu(Time/latency of a trigger),
TriNo(Trigger number), Comnt(Condition name)...

Tmu             Code    TriNo    Comnt
1723000            1    10    Trigger - snd+
1723000            1    2    Trigger - DIN

2518000            1    2    Trigger - DIN
2518000            1    10    Trigger - snd+

3315000            1    2    Trigger - DIN
3315000            1    10    Trigger - snd+

4112000            1    2    Trigger - DIN

Thanks!

On Wed, Sep 14, 2011 at 2:48 AM, Arnaud Delorme <arno at ucsd.edu> wrote:

> Dear Chang,
>
> do you think one reason why the EDF files look different in EEGLAB could be
> that EDF is 16-bit and that your data is probably 18+ bits?
> There are 2 functions to import EDF in EEGLAB (2 plugins), did you try the
> other one? When you reimport the EDF file in BESA you have exported in BESA,
> does it look different as well or is it just in EEGLAB. We do not have BESA
> so it is hard for us to track down that issue. I feel pretty confident about
> the BIOSIG function, although it is true that we have been arguing a couple
> of years ago with the author of the function about minor signal calibration
> issues.
>
> Best,
>
> Arno
>
> On Aug 25, 2011, at 1:22 AM, Chang Gu wrote:
>
> Hi all,
>
> I'm trying to transfer data between EEGlab and BESA for eye blink
> correction and artifact rejection. But when we exported the EEG data from
> Besa in simple binary format (.dat file) and read it by EEGlab using 'Import
> data:  FromASCII/float file or Matlab array', the potential value of the
> data was rounded and we lost the decimal parts (e.g 80. 232 changed to 80).
> I also tried to have BESA export data in ascii format, but still only have
> integer part. I suspect that BESA rounds the Continuous data automatically
> to the integer (since I use Matlab *fread() *read the .dat, but only see
> the integers.)
>
> Another option is to export the data as .edf file and use biosig plugin in
> EEGLAB to read it.
> The .edf from BESA preserves the decimal part, but the value changed
> somehow in EEGLAB... I'm not sure if the plugin works correctly or not...
> (Someone looks into this function and compared the results?)
>
> Does anyone know how to export (continuous) data from BESA to EEGLAB
> without losing resolution?
>
> Thanks!
>
> Chang
>
> --
> Chang Gu
> Psychology & Human Development
> Vanderbilt University
> Nashville, TN
>
>
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-- 
Chang Gu
Psychology & Human Development
Vanderbilt University
Nashville, TN
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