Cutting of sampled signal into two parts

Hi everone,

Actually I have EEG signal (having dimension 1875*22*66 ) which is sampled at 250 Hz. I want to cut it into two parts as from 1 Hz to 125 Hz and 126 Hz to 250 Hz. How to do that?

[Rik]

Comment mistakenly posted as answer by Jingwei Too:

Dear Rasheed Asad,

Your question is not clear. The dimension is sample*channel*repetition or what ? This needed to be clear before start the window segmentation part.

[Rik]

Comment posted by Rasheed Asad (with edit mistakenly included in a flag):

Dear Jingwei Too,

Thanks for your valued comment. Actually signal is 7.5 second longer and sampled at 250 Hz, so therefore there will be 1875 samples in a EEG signal. Here is the description of above matrix with respect to its dimension for your consideration;

1875*22*66 = number of Samples * number of Electrodes * number of Trials.

Note: Please keep in mind, I am hoping splitting of EEG signal in frequency domain, not in time domain.

[Rik]

This is not really my field of expertise, but once you have a Fourier transform, it shouldn't be too hard to split the signal. You should be able to make a copy of the variable and then setting the parts you don't need to 0.

I guess your main question is if you want to fourier analyze the entire signal of an electrode, or smaller portions separately.

Answer 1

[Jingwei Too]

Dear Rasheed Asad,

There are several ways to do that:

(1) You can use fast fourier transform (FFT)

(2) You can use short time fourier transform (STFT) to make it too

(3) The best way should be wavelet transform (WT). I will suggest discrete wavelet transform (DWT) which can decompose the signal into approximation and detail coefficients. You can refer paper " 2010 EEG signal classification using PCA, ICA, LDA and support vector machines".

[MAT-Magic]

Dear Jingwei Too,

Thanks for the comment. Actually, I am using continuous wavelet transform (CWT) for Time-Frequency mapping. Is it possible to split the signal into two parts (in frequency domain) by using CWT?

[Jingwei Too]

Dear Rasheed Asad,

I am afraid that i cannot lend you too much assist on CWT since CWT is not my expertise. If you have Matlab wavelet toolbox, you may try to refer the example in help and those might help you for your study.