Neurosky and SSVEP

[Mariam1311]

Good morning

I am using the neurosky mindwave mobile headset and labview in order to test the brain signals for SSVEP response, however when I test for the peaks in the frequency response I don't find any at the desired frequency, So is this problem from the neuroksy mobile headset or that the sampling rate of the power frequency is not enough or for any other reason??

Thank you!

[nickstorton]

Hi,

What is your sampling rate and what is / are your desired frequency?

Nick

[Mariam1311]

I used the NeuroSky LabVIEW driver with the sampling rate of 512 HZ to read the raw EEG data and then used the power spectrum VI in the express VIs, the stimulus frequencies are: 8 Hz and 15 Hz and these are my desired ones.

Thank you so much for your quick reply!

[nickstorton]

Hi,

Your sample rate should be just fine for these desired frequencies. Is it possible to post a view of the spectrum you are getting?

BR

Nick

[Mariam1311]

when I plot the frequency spectrum it does not plot right, it gives a constant peak at 0.1 Hz however when I use an array to see the values it gets frequencies @1,5,11 Hz and vaires at them, when I introduce the stimulus it doesn't produce a peak at 8 hz or 15 hz...

Would  you like me to post the whole program??

Thank you!

[nickstorton]

Hi,

The 0.1 Hz you are seeing is probably the DC component. If the program is not too large then post it and I will take a look for you.

BR

Nick

[Mariam1311]

Thank you loads,

here is the program, it takes the signals from the neurosky mindwave mobile, does a power spectrum on the signal and checks for the peaks..

[nickstorton]

Hi,

I don't have the NeuroSky driver so cannot look at the whole program but one thing that strikes me is that you say you are acquiring the data at 512 Hz from the driver but when you lowpass filter the denoised signal your sample rate is set to 100 Hz. This may well have the effect of shifting peaks. I would try running with the filter sample rate set to match the data sample rate.

BR

Nick