EEG Signal Features Extraction using DWT

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David Lee
David Lee 2018-12-2
回答： Alla Zwawi 2022-1-20
Hi, all.
I am currently doing an analysis on an EEG signal. The raw EEG signal has been pre-processed using a band pass filter to its Alpha Band. Then, the pre-processed EEG signal will undergo Feature Extraction using DWT to extract a specific frequency. Following is my code for 1-D DWT, however after the decomposition, the graph plotted was in time domain. I need help on how to convert it to frequency domain?
%DISCRETE WAVELET TRANSFORM, 5 level wavelet db2
waveletFunction = 'db2';
[C,L] = wavedec(ep5,5,waveletFunction);
cD1 = detcoef(C,L,1); %NOISY
cD2 = detcoef(C,L,2); %Gamma
cD3 = detcoef(C,L,3); %Beta
cD4 = detcoef(C,L,4); %Alpha
cD5 = detcoef(C,L,5); %Delta
cA5 = appcoef(C,L,waveletFunction,5); %Theta
subplot(6,1,1)
plot(cA5)
title('Approximation Coefficients Theta')
subplot(6,1,2)
plot(cD5)
title('Level 5 Detail Coefficients Delta')
subplot(6,1,3)
plot(cD4)
title('Level 4 Detail Coefficients Alpha')
subplot(6,1,4)
plot(cD3)
title('Level 3 Detail Coefficients Beta')
subplot(6,1,5)
plot(cD2)
title('Level 2 Detail Coefficients Gamma')
subplot(6,1,6)
plot(cD1)
title('Level 1 Detail Coefficients Noise')
Your help will be highly appreciated. Thank you very much.
  1 个评论
thejaswini M S
thejaswini M S 2021-11-5
hello ,i have difficulty in computing DWT for EEG signals for emotion recognition ...please can i have entire code for computing DWT

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回答（2 个）

VISHWANATH KOLLIYAVAR
post the output waveform of this code
Alla Zwawi
Alla Zwawi 2022-1-20
I think a very easy way to convert the extracted wavelets is to use fourier transform or FFT to get the power spectrum of frequency bands and then plot that.

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