CMS and DRL

CMS and DRL for EEG electrodes

Last week, I am trying to find out what CMS and DRL in my Emotiv EPOC are. For my experiment(s), those electrodes are used reference (REF) and ground (GND) on EEG cap. From the documents, which are found or given, CMS is used as REF and DRL is used as GND. It is unknown whether that configuration is compulsory or optional.

From Biosemi website, I got good explanation about CMS and DRL.

• CMS is Common Mode Sense, active electrode
• DRL is Driven Right Leg, passive electrode

They form a feedback loop for references for Analog-to-Digital Converter (ADC) of other electrodes. The schematic of CMS and DRL from Biosemi is shown below.

Explanation of CMS and DRL from Biosemi website

In my electrical engineering view, as passive electrode, DRL is suitable for ground. CMS, as active electrode, can be treated as reference on the head. Both will perform looping to get references in ADC for other electrodes. The idea is understandable for me.

CMS & DRL. http://t.co/ngeXtbCi5C http://t.co/pan9SFjjes
— iscab.saptocondro (@saptocondro) February 4, 2014

My curiosity about CMS and DRL can be read on  my other blogs:

• PhD note on February 11th, 2014
• PhD note on February 9th, 2014
• PhD note on February 3rd, 2014 

Well, I am still hoping that my research is going in the right direction.

Bremen, 11 Februari 2014

iscab.saptocondro
Darah Juang!

Brain Robot Research, a neuroscience blog http://iscabrainrobot.blogspot.com/2014/02/cms-and-drl.html