OpenViBE forum

Hi there
I am currently working through the motor-imagery-bci-2-classifier-trainer using Emotiv Epoc. I obtained the following error

[ ERROR ] At time 0.141 sec <Box algorithm::Reference Channel> Channel not found [Nz]
[WARNING] Box algorithm <Reference Channel> has been deactivated because process phase returned bad status

What should I be using for the reference channel?

Hi,

The Reference channel box substracts the value received on the reference to the other channels.
This is useful with some EEG devices. The reference is usually placed on a spot where only the noise remains (e.g. on the nose). Doing so will remove the acquired noise on the other channels to get a cleaner signal.

The Emotiv headset does not have such electrode, thus the reference channel box is not needed. You can remove it from your scenario.
I'm afraid you may have to change other boxes in these scenario (the basic motor imagery example uses a Surface Laplacian as a spatial filter, it won't even work with the emotiv electrode placement).

I suggest you use the motor-imagery-CSP scenarios instead of the no-CSP ones.
The CSP spatial filters should help find the best channels, regardless of their position, and you won't have much work to do to adapt the scenarios to the Emotiv data.


Hope this helps !

Laurent-