Emotiv Epoc data timing error with P300 Speller

This forum deals with BCI2000 configuration issues.
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jamesawi
Posts: 1
Joined: 03 Mar 2011, 15:27

Emotiv Epoc data timing error with P300 Speller

Post by jamesawi » 20 Mar 2011, 19:20

Hi all,

I am using an Emotiv Epoc with Research SDK with BCI2000's P300 Speller and am running into the following error: "DataIOFilter::EvaluateTiming: Roundtrip time consistently exceeds block duration (currently 120.05%)."

This error occurs after the first round of spelling, preventing further spelling sessions until a full program restart is applied. I have followed the instructions written here: http://www.bci2000.org/wiki/index.php/C ... ons:Emotiv, and have set my sample block size as recommended to 4, so the duration is 31.25ms. I have tried reconfiguring the stimulus time in the config parameters to be larger or smaller, but the same error still plagues me.

Any thoughts/suggestions are much appreciated!

Best,

Jamie Williamson


EDIT: I found this post http://72.249.19.64/phpbb/viewtopic.php?f=5&t=908 regarding my exact question, but the answer seems to be: "buy a faster machine." I obviously cannot do this, so is there any configuration suggestions that would alleviate the problem in software? I am referring to downsampling the data, increasing stimulus times, reducing the list of transmitted channels, etc. Thanks!

EDIT2: I solved my issue by increasing the block size to 16, and increasing StimulusDuration to 125ms and ISIMinDuration and ISIMaxDuration to 250ms each. Getting close to 85% online free spelling accuracy after classification! =]

Kalvin
Posts: 14
Joined: 02 Sep 2011, 05:06

Re: Emotiv Epoc data timing error with P300 Speller

Post by Kalvin » 15 Sep 2011, 07:58

Thanks for the hints on the parameters - what are your system specifications? It would be interesting to know something like a minimum.

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