[FieldTrip] Amplifier for EGI-data in fieldtrip???

Joseph Dien jdien07 at mac.com
Thu Sep 6 03:17:03 CEST 2012


The Simple Binary (.raw) files don't get corrected for gain when imported (I helped write them).  I've experienced occasional unpredictable bugs with NetStation export routines where the files are generated with amplitudes many times too large, even with text format files.  It's a bit disconcerting to say the least.  I could take a look at your files if you'd like confirmation.

Joe

On Sep 4, 2012, at 4:00 PM, Ingrid Nieuwenhuis <inieuwenhuis at BERKELEY.EDU> wrote:

> Hi Daria,
> 
> Also, did you try looking at your raw data (so before the ERPs are made) in FieldTrip and in Net Station? So open your .raw data in NetStation. You can just look at a random participant's data, and     check if the scale is the same. I'm pretty sure no amplification takes place when reading in the data into FieldTrip, this check can confirm that. Hope this helps, and let us know what you find.
> 
> Cheers,
> Ingrid
> 
> 
> On 9/3/2012 1:35 PM, Robert Oostenveld wrote:
>> Hi Daria,
>> 
>> There might indeed be an incompatibility in the gain  value applied to the data.
>> 
>> If you are able to export the data using the EGI software in another format (e.g. EDF), you could read them both into FieldTrip and compare the timecourse aplitudes to check whether they are different. In case they are, I suggest to involve EGI support. They are aware of the FieldTrip reading functions and will know much more about the internals of their various file formats.
>> 
>> best regards
>> Robert
>> 
>> 
>> 
>> 
>> On 3 Sep 2012, at 17:22, Daria Laptinskaya wrote:
>> 
>>> Dear Fieldtrippers,
>>> 
>>> I analysed EGI-data (.raw-files, NetStation 4.3.) with the fieldtrip toolbox. 
>>> The ERPs look perfect. 
>>> The 'only' problem is, that my signals look to strong.
>>> It looks like if I get amplitutes (average) until 70 ┬ÁV. 
>>> I think it must be an intern amplifier for the signals.
>>> Does anyone know this problem with EGI-data?
>>> 
>>> Or does anyone know, where I can see the amplifier?
>>> 
>>> 
>>> 
>>> 
>>> Greetings,
>>> 
>>> Daria _______________________________________________
>>> fieldtrip mailing list
>>> fieldtrip at donders.ru.nl
>>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>> 
>> 
>> 
>> _______________________________________________
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> 
> -- 
> Ingrid Nieuwenhuis PhD
> Postdoctoral Fellow
> Sleep and Neuroimaging Laboratory
> Department of Psychology
> University of California, Berkeley
> California 94720-1650
> Tolman Hall, room 5305
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip


--------------------------------------------------------------------------------

Joseph Dien,
Senior Research Scientist
University of Maryland 

E-mail: jdien07 at mac.com
Phone: 301-226-8848
Fax: 301-226-8811
http://joedien.com//










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