bci2000.org BBS

What Chad is describing is a realization of synchronous Matlab processing, i.e., processing of blocks of data as they are "p[roduced" by the data acquisition device. As an alternative, for asynchronous processing, you may want to look into the FieldTrip buffer (described on the Wiki).

Gerv

Check the SelectedRow and SelectedColumn state:

http://www.bci2000.org/wiki/index.php/U ... pellerTask

Gerv

Check out

Goncharova, I. I., et al. "EMG contamination of EEG: spectral and topographical characteristics." Clinical Neurophysiology 114.9 (2003): 1580-1593.

It should have answers to all your questions.

Gerv

I have never heard about this problem, even though we and many others have been using BCI2000 extensively with synced g.USBamps. My best guess is that this issue has something to do with the particular configuration you are using. I would try to switch the order of the two amps, including switching ...

Why don't you use BCI2000's StimulusPresentation module instead of ePrime?

Gerv

I do not think that a sporadic 16 ms jitter will affect the P300 system very much. We have been very successful with P300 experiments with wireless EEG devices that typically have quite poor timing performance.

Gerv

I think I am running out of possible reasons for this. We definitely know of (even much more demanding) configurations that do not show these irregularities. The only thing I can still think of is to try a different computer, or to see if you can increase the polling cycle of the USB controller and/...

A few more ideas. #1: I understand you do 256 Hz. What is the SampleBlockSize? #2: Does anything change if you go to 16 channels on each amp (32 total)? #3: How did you connect the g.USBamps? If you use a USB splitter, or even otherwise, they may be on the same USB controller, and what you see may b...

What happens when you use the TaskManager to set the CPU Priority of the Source module to Real Time?

Gerv

Which BCI2000 version are you using?

Gerv

Robin,

Check

http://www.bci2000.org/wiki/index.php/U ... nce:Timing

Gerv

Andrew,

I would suggest to contact g.tec to get a new driver. Yours appears to be ancient.

Gerv

The D2Box task of BCI2000 v1.0 could only present targets in a block-randomized fashion, i.e., you cannot use a predefined sequence unless you use v2.0 or you change the D2Box code. All earlier BCI2000 versions, including the D2Box code, are still available on SVN.

Gerv

Hi, BCI2000 does not come with a general-purpose classification tool for analyzing SMR activity other than OfflineAnalysis. The most important reason for this is that appropriately interpreting mu rhythm activity depends in part on expert interpretation of brain signal patterns (e.g., to differentia...

Hi, The format of the results is certainly the same whether or not you have high accuracy. Based on everything you write, it seems like your Matlab program cannot keep up reading the values from BCi2000 sent via UDP. You could check the Windows TaskManager -- Matlab is probably consuming a whole CPU...