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Problems with NeuroRT dry sensor driver with DSI-24 device

Posted: Wed Aug 09, 2017 6:24 am
by aizmeng
Is this a bug about A1 channel lost with the NeuroRT Driver Collection[Wearable Sensing Dry Sensor Interface]?

Openvibe v1.2.2 was used. I used NeuroRT Driver Collection[Wearable Sensing Dry Sensor Interface] as the driver and the wearable sensing' DSI-24 device was used as EEG device.
The DSI-24 device can be connected to the Openvibe Acquisition Server. However, for the designer part, some channel data can be seen by using signal-display.xml and the A1 channel was lost.
For DSI-24, there are 24 channels,including P3,C3,F3,Fz,F4,C4,P4,Cz,Pz,A1,Fp1,Fp2,T3,T5,O1,O2,X3,X2,F7,F8,X1,A2,T6,T4.
The obtained EEG signals does not contain the A1 channel, someone can help me?

Re: Problems with NeuroRT dry sensor driver with DSI-24 devi

Posted: Fri Aug 11, 2017 2:25 pm
by Mensia Support
Dear aizmeng,

We were not reported this bug, but this driver was not tested with a DSI-24, since we support DSI-7.

A1 seems like an auxiliary channel, that may not be active by default, you should try to check option "Acquire Auxiliary Channel".

Also note that in "Cap montage" you should choose the "Let the driver decide" montage rather than "Custom electrode montage", otherwise your channel names will be overwritten.

Hope this helps, regards,

Morgane, Developer at Mensia Technologies

Re: Problems with NeuroRT dry sensor driver with DSI-24 devi

Posted: Sun Aug 13, 2017 1:49 pm
by aizmeng
Thanks for your reply. However, the A1 channel is not an auxiliary channel, just a reference channel located the earlobe.
In OpenVibe v1.2.2, there is no "Cap montage" configuration item, just the Aquisition Server Configuration---Drift Correction including the "Let the driver decide".
Mensia Support wrote:Dear aizmeng,

We were not reported this bug, but this driver was not tested with a DSI-24, since we support DSI-7.

A1 seems like an auxiliary channel, that may not be active by default, you should try to check option "Acquire Auxiliary Channel".

Also note that in "Cap montage" you should choose the "Let the driver decide" montage rather than "Custom electrode montage", otherwise your channel names will be overwritten.

Hope this helps, regards,

Morgane, Developer at Mensia Technologies

Re: Problems with NeuroRT dry sensor driver with DSI-24 device

Posted: Fri Nov 20, 2020 12:57 pm
by AsherLi
Same to me, I try to use 'NeuroRT Collection: Wearable Sensing DSI' in acq server in openvibe to acquire signals from DSI-24 device. However, i can only get 23 channels as 'A1' channel is missing, Is there any solution ?

Re: Problems with NeuroRT dry sensor driver with DSI-24 device

Posted: Wed Mar 03, 2021 2:34 pm
by wsoussou
Hi All, sorry for the delay in posting the answer to this:

Kindly note that, by default, the headset re-references Channels to the "traditional" reference, which is: (A1 + A2)/2, often called Linked-Ears.

Therefore API delivers
A2 – ((A1+A2)/2), which is the negative of A1 – ((A1+A2)/2)

A1 is not delivered, as it is just the negative of A2, so users can generate A2 by negating A1.

Here’s the math:

A2 is actually: A2 - (A1 + A2)/2 = A2/2 - A1/2
A1 is actually: A1 – ((A1+A2)/2) = A1/2 - A2/2

So A1 = -A2

Hope this helps,
We will add A1 in a future release of the API.

Thank you,
Walid on behalf of the Wearable Sensing Support Team