Extracting Peak Alpha Frequency and IAF

Working with OpenViBE signal processing scenarios and doing scenario/BCI design
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Mike_qp
Posts: 5
Joined: Sat Apr 03, 2021 1:38 pm

Extracting Peak Alpha Frequency and IAF

Post by Mike_qp »

Dear all,

I'm sorry if this subject has already been treated, yet i found nothing on it.

My question is pretty simple : i'm trying to find a way to assess peak alpha frequency in real time (frequency corresponding to max(pow) in alpha range), to use it as my main BCI parameter.

Is there a function i'v missed to do so ?

Another related question : if i want to assess the true individual alpha frequency (IAF) defined as
IAF = Sum(Pow(f)xf) / Sum(Pow(f))
Is it possible to get the power at each frequency bin in real time and process the formula above in a simple DSP box ?

Thank you very much for all your help

Cheers

Thibaut
Posts: 231
Joined: Wed Oct 31, 2018 9:14 am

Re: Extracting Peak Alpha Frequency and IAF

Post by Thibaut »

Hello,
I'm not sure what you want to do.
To limit the frequency bands, you have the "temporal filter".
To separate the frequency bands and have the power of each, you have the "spectral analysis".
For the average of your signal (per channel) you have the "signal average".
The simple DSP will apply an operation on all the epochs that you recover (if you made a signal average you have only one value in your epoch. Otherwise on average the epochs have 32 samples.)
I have the impression that you want to do a gradient descent or something like that to find the best frequency, in this case, I advise you to make a script for the python box.
Thibaut

Mike_qp
Posts: 5
Joined: Sat Apr 03, 2021 1:38 pm

Re: Extracting Peak Alpha Frequency and IAF

Post by Mike_qp »

Thank you for tour answer,

I don't want to do anything as complicated actually. My need is pretty simple : to get the frequency at the maximum amplitude of a band of interest (Say alpha). When You close your eyes, your alpha oscillations are characterised by a clear peak between 8-12 hz. I want a way to get the frequency corresponding to this peak it in real time.

Cheers

Thibaut
Posts: 231
Joined: Wed Oct 31, 2018 9:14 am

Re: Extracting Peak Alpha Frequency and IAF

Post by Thibaut »

Hi,
So you can use the spectral analysis to see value of each frequency in real time. But to have the best band, you must implement an algorithm (the fatest wy for no developper is to use python) with gradient descent or other way.
Thibaut

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