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Actiview display settings + offsets

Posted: Tue Feb 21, 2023 6:22 pm
by ducttapelab
Hi there,

We have a 128 channel system from yourselves. I have a few questions regarding interacting with the actiview pane:

1) We have been aiming for the lowest possible offsets, usually <20, however, on occasions some values are closer to 40. Would you say this is still within an acceptable range?

2) On occasions, and having read the forum, it seems that there is often bridging between the drl and surrounding electrodes. Would you expect all 128 channels to have clean readouts or is it inherent that there will quite often be some noisy channels?

3) When viewing the live data, what would be the recommended level of ‘zoom’/y-scale to have the display at? At what level is it applicable to check for ‘noisy channels’?

4) What is the recommended low/high pass filters to have when using actiview? 0.16/30?

Thanks so much!

Re: Actiview display settings + offsets

Posted: Thu Feb 23, 2023 3:57 pm
by Coen
Offsets should be stable and approximately within the +50 mV to -50 mV range. Trying to get them closer to zero does not improve anything.

Bridging with DRL (50 Hz noise) or CMS (flat line) indicates that you use too much gel. In that case, there are probably several other gel bridges (adjacent electrodes with identical waveforms). Use just enough gel to fill the cavity, but not more. Prevent the cap from shifting on the head after gel is applied. All (128) electrodes should be noise free.

Data is typically viewed with the 100 or 50 uV scale setting and 0.16 - 100 Hz bandwidth (data to file is always full bandwidth).

Best regards, Coen (BioSemi)

Re: Actiview display settings + offsets

Posted: Thu Feb 23, 2023 4:30 pm
by ducttapelab
Absolutely brilliant - thank you so much for that detailed reply! I will make use of your knowledge during upcoming data collection