Plot a multichannel signal to identify the frequency value
3 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Riddhi Gala
le 20 Juil 2018
Modifié(e) : Jesus Sanchez
le 23 Juil 2018
I have a multi-channel EEG data of size 64x1000, where 64 is the number of channels and 1500 time points. I already know that this signal is of 8Hz. I want to plot this signal to show that there is a peak 8Hz indicating the signal frequency.
How can I do it??
0 commentaires
Réponse acceptée
Jesus Sanchez
le 20 Juil 2018
Modifié(e) : Jesus Sanchez
le 20 Juil 2018
I would do a fast fourier transform for each channel (fft in matlab), so you have the frequential componentes of each channel. Then just use a function such as mesh, surf or pcolor. As these functions represent 3D surfaces, I would define X as channel, Y as frequency and Z as the value given by the FFT.
So in general lines the code will be something like this:
nFFT = 2048; % I asked for 2048 frequency points because why not.
nChannels = 64;
data_freq =fft( multi-channel-EEG-data.',nFFT);
% FFT is applied to columns, that is why it is neccesary to transpose them.
x = 1:nChannels;
y = 1:nFFT;
[X,Y]=meshgrid(x,y);
figure
mesh(X,Y,data_freq);
shading interp;
I did not try the code, so there are probably several mistakes, but if you follow this lines, it should work :). You might need to apply another .' to data_freq to represent it. Good luck!
2 commentaires
Jesus Sanchez
le 23 Juil 2018
Modifié(e) : Jesus Sanchez
le 23 Juil 2018
Can you upload your data? If there is a peak appearing somewhere different from 8 Hz, it could be that the plot is shifted. Moreover, maybe 2048 points for the FFT is too little. Try to do it directly with
fft( multi-channel-EEG-data.');
and see if that works.
Plus de réponses (0)
Voir également
Catégories
En savoir plus sur Annotations dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!