Emotiv Epoc-data through Openvibe_ with DC offset?

Making & changing hardware drivers in Acquisition Server
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hkn1304
Posts: 13
Joined: Tue Apr 18, 2017 5:44 am

Emotiv Epoc-data through Openvibe_ with DC offset?

Post by hkn1304 »

Hello,
My question is about Epoc in openvibe.

Is the received data from Epoc through Openvibe with DC offset or not?
Also, is the received data type uint16 or microvolts?

All in all, what should i need to do to get received data(true,without any DC offset) in microvolts format?

Thanks in advance.
Hakan

jtlindgren
Posts: 778
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: Emotiv Epoc-data through Openvibe_ with DC offset?

Post by jtlindgren »

Hello Hakan,

the data is passed through as-is it comes from the Emotiv SDK function IEE_DataGet(). There's a mention in our code that

// Various sources (e.g. http://emotiv.com/forum/forum15/topic87 ... ?PAGEN_1=3
// and http://www.bci2000.org/wiki/index.php/C ... ons:Emotiv ) suggested
// that the units from the device are in microvolts, but with a typical DC offset around 4000.
// Hard to find official source.

If you wish to know what exactly is in it, you should ask Emotiv who is the only party that knows for sure what their proprietary, closed source library/hardware returns. For many use cases, the DC offset shouldn't matter and will be removed by temporal filtering.


Hope this helps,
Jussi

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