drifts in channels & import into vision analyzer

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N.K.
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Joined: Thu Dec 18, 2008 2:30 pm
Location: Switzerland

drifts in channels & import into vision analyzer

Post by N.K. »

hello!

i have a problem with huge drifts in all channels - they go down to -5800 mikro volt. is there possibly a filter i forgot to attach, or any other way i could change/ prevent that from happening?
do you think it could be a problem connected to importing data through eeg lab into vision analyzer?

thanks a lot for your help!

Coen
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Post by Coen »

ActiveTwo is a DC system, signals are stored to BDF file without any high-pass filter.

During review, you should normally aplly a high-pass filter to suppress drift in the electrode offset voltages.

Best regards, Coen (BioSemi)

terracop
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Joined: Tue Mar 03, 2009 9:57 pm
Location: Europe

Post by terracop »

I think you should try to get the source of the problem fixed not filtering the data. DC drifts will occur only if preparation is not done in an appropriate way or sweating artifacts may cause the drifts. DC recordings require some patience as well after inserting the gel. So make sure the preparation is ok and instruct your volunteer afterwards to gain time until the DC potential on the head is kind of normalized. DC recordings are not "quick shots". Highpass filtering during the recording will of course avoid dc drifts. Again, filtering will only "beatify" the data online or offline.

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