EEG raw voltage

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maarcc2050
Posts: 27
Joined: Sun Jan 17, 2010 1:23 pm
Location: Brisbane

EEG raw voltage

Post by maarcc2050 »

Hi.

What should be the raw voltage range we expect to see when using Biosemi to record EEG?

We recorded some EEG signals in a bdf file. When we open this raw bdf file (raw = no processing done), we see that some channels' voltages fall in the positive microvolt values, while some channels fall in the negative range. E.g. Channel 29 drifts in the negative voltage range (-2900 to -2300) while channel 30 drifts in the positive voltage range (+9500 to +7800)

What decides/influence if a channel will be in positive or negative voltage range? If we record using other EEG hardware not from biosemi, are we expected to see similar results (if all being equal)?

Thank you.

Coen
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Post by Coen »

It is a DC system, the electrode offset determines the DC value (between +262 mV and -262 mV), LSB = 31.25 nV, apply high-pass or baseline correction to remove offset values, select a reference and subtract this reference form all channels to remove Common Mode noise.

Best regards, Coen (BioSemi)

maarcc2050
Posts: 27
Joined: Sun Jan 17, 2010 1:23 pm
Location: Brisbane

Post by maarcc2050 »

Could you recommend a base line correction method?

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