[Eeglablist] problems with bdf files

[Panin, Francesca]

Thanks a lot!

I did remove the DC Offset and now I can see all my signals

Thank you very much both for your help

Francesca
________________________________________
From: eeglablist [eeglablist-bounces at sccn.ucsd.edu] on behalf of Matt Craddock [m.p.craddock at leeds.ac.uk]
Sent: 25 June 2017 10:47
To: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] problems with bdf files

Hi Francesca,

The first problem is likely just because of the dynamic range of the
BioSemi signals - the channels have very different DC offsets, so some
are out of display range. For display purposes, when you're using the
Channel Data Scroll, then selecting the Remove DC Offset option should
make all the data re-appear. More generally this problem will disappear
if you use a high-pass filter, or if you epoch the data and baseline
correct it.

Second problem - best guess is you might have recorded from 263 channels
even though you only had 32. It's perfectly possible to record empty
channels if the recording software is set up incorrectly. In the
pop_biosig interface it'll give you the option to choose which channels
to load, so just do that - by default it will load all channels present
in the recording. Check how your recording software is set up. Not sure
what Cartool does on import or for display so, it's quite possible it's
removing flatline channels, high-passing the data etc...

Cheers,
Matt

On 23/06/2017 10:11, Panin, Francesca wrote:
> Hi
>
> I have problems opening some BDF files
>
> I keep using the commands illustrated in the guidelines and each time I
> obtain something different!
>
> The problem is not in the file as I could open the data without problems
> using another software called Cartool
>
> I used the command Import data>From Biosemi BDF file and then I leave
> the default options in the two subsequent dialogue boxes and I just click ok
>
> What I obtain is either:
>
> - I can see only one wave in the middle of the plot (but there are 32
> channels)
> or
> - I obtain 263 channels (and, again, I should only have 32)
>
> does anybody know how to help?
>
> Thanks very much
>
> Francesca
>
>
> --
> http://www.anglia.ac.uk/email-disclaimer
>
>
>
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to eeglablist-request at sccn.ucsd.edu
>
_______________________________________________
Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
To unsubscribe, send an empty email to eeglablist-unsubscribe at sccn.ucsd.edu
For digest mode, send an email with the subject "set digest mime" to eeglablist-request at sccn.ucsd.edu