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Calculation of FFT power for offline analysis

Posted: 03 Sep 2018, 07:05
by marnan
Dear BCI2000-Community

I have some basic questions regarding the calculation of FFT/AR spectrum in the BCI2000. Currently, I use the FFT as an option of the ‚SpectralEstimator‘. To double check my results, I wanted to do an offline analysis with the entire signal processing pipeline in Matlab. By doing that, some issues/questions popped up:

1. Is there something similar to the ‚men‘-function (AR spectrum) for the FFT spectrum offline calculation? If not, what is the exact FFT implementation, which I can use for the Matlab offline processing?
2. What is the FFT frequency resolution? By using a ‚WindowLength‘ of 0.5s, the frequency resolution should be 2Hz. However, what role plays the parameter ‚BinWidth‘ then? Is this parameter only active for the AR calculation? Moreover, have the parameters ‚FirstBinCenter‘ and ‚LastBinCenter‘ the same function as in the AR calculation?
3. Are there any general recommendations whether to use AR or FFT? What are the pros and cons of both? Moreover, applies the community detrending and/or windowing function?

Thanks a lot for your help!

Re: Calculation of FFT power for offline analysis

Posted: 23 Oct 2018, 09:48
by mellinger
Hi,

to help answer you questions, more detailed information has been added to the BCI2000 wiki:
https://www.bci2000.org/mediawiki/index ... lEstimator

Let me know if you need further clarification.

-Jürgen