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:
Well, I am still hoping that my research is going in the right direction.
Bremen, 11 Februari 2014