## Using Matlab FFT to extract frequencies from EEG signal

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I am new to BCI. I have a Mindset EEG device from Neurosky and I record the Raw data values coming from the device in a csv file. I can read and extract the data from the csv into Matlab and I apply FFT. I now need to extract certain frequencies (Alpha, Beta, Theta, Gamma) from the FFT.

Where Delta = 1-3 Hz

Theta= 4-7 Hz

Alpha = 8-12 Hz

Beta = 13-30 Hz

Gamma = 31-40 Hz

This is what I did so far:

f = (0:N-1)*(Fs/N); plot(rawDouble); title ('Raw Signal'); p = abs(fft(rawDouble)); figure,plot (f,p); title('Magnitude of FFT of Raw Signal');

Can anyone tell me how to extract those particular frequency ranges from the signal?? Thank you very much!

For convenient analysis of EEG data with MatLab you might consider to use the EEGLAB toolbox (http://sccn.ucsd.edu/eeglab/) or the fieldtrip toolbox (http://fieldtrip.fcdonders.nl/start).

Both toolboxes come with good tutorials:

http://sccn.ucsd.edu/eeglab/eeglabtut.html

http://fieldtrip.fcdonders.nl/tutorial

**EEG signal FFT and band extraction and avg power as a feature ,** EEG signal FFT and band extraction and avg power Learn more about matlab coder, signal processing, spectrum analysis, eeg, fft. I have a sample EEG signal from MIT data set and has a sampling frequency as : 500 hz. In my example, I will create a 1Hz sinewave with an amplitude of 1, phase of 0 degrees, and based on a 250Hz sampling, and then I will use the FFT function to extract the frequencies found within. Using the MATLAB script below, in a new script and clean workspace, I created a sine wave consisting of a 1Hz and 5Hz signal:

You may find it easier to start off with MATLAB's periodogram function, rather than trying to use the FFT directly. This takes care of windowing the data for you and various other implementation details.

**How to do FFT Analysis to EEG signals Using Matlab,** I'm looking for FFT analysis to EEG or ECG signals in MATLAB. I have tested aVLF=trapz(psdperiodo.frequencies(iVLF),PSD(iVLF))*10^6;. The nonparametric PSD estimates in MATLAB like the periodogram and Welch estimator already "normalize" the result to create the PSD estimate. For example, in the periodogram with the default rectangular window, the magnitude squared DFT values are "normalized" by dividing by the length of the input and the sampling rate as you state in your post, although for a one-sided PSD estimate, the

I think the easiest way is to filter your signal in those ranges after you load your data. E.g.

band=[30 100] eeglocal.lowpass(band(2)).highpass(band(1));

then you can use select the time you want to process.

That should be all you need.

**looking for an existing code in matlab that analyze EEG signals by FFT,** This function provides signals that supposed to represent EEG signals (with the same amplitude and frequency values). My code should receive this input data ( I have a sample EEG signal from MIT data set and has a sampling frequency as : 500 hz. Please help me for my below finding: - I need to divide the time signal in 3 windows. - Apply FFT on each for each window signals - Find the average power within each frequency band: theta(4-7 hz), alpha(8-13 hz), beta(13-30hz).

**Extracting EEG Components from Signal,** I have a simple EEG signal in MATLAB such as that shown in the figure below. Then, you may use FFT function to transform the signal into frequency domain. For example, if we are taking EEG from an Emotiv headset, we can be unable to predict the frequency is present in our EEG waveform. However, we can take FFT to determine the frequency in our signal. Sometimes, we may have an unknown frequency of our signal and we need to remove noise. We can’t do this unless we know the frequency of the original signal and the frequency of the noise signal. The Fast Fourier Transform is one of the tool to find the signal frequency. After this, we can apply

**Need to break down EEG signals into 4 frequency bands,** I have attached the signal EEG recording with this, it has 22 arrays, the eeg channels are from 2 - 15 and the sampling frequency is 128. thank you! I am trying to extract lower alpha (8-10Hz) and upper alpha (10-13Hz) frequency from EEG signal. I have already extracted Alpha, Beta , Gamma and theta bands using Wavelet decomposition in MATLAB

**how to obtain the frequencies from the fft function,** on 6 Apr 2020. after the fft of the input signal,how to get the frequencies? I have 10 seconds of EEG recording that I have used fft on. How can I obtain the I have EEG signal from which i need to extract frequency information. The signal have x-axis as number of sample and y-axis as amplitude. if am applying fft on signal its giving me frequency in KHz.

##### Comments

- Look at the MATLAB documentation for bandwidth filters. That should be easier than going through an fft first.
- PLEASE ANYBODY ANSWER TO MY QUESTION HERE stackoverflow.com/questions/23167374/…