How to extract frequency sub-bands of an EEG signal using wavelet packet transform?

i want to decompose a signal with wavelet in 5 subbands: delta (0–4 Hz), theta (4–8 Hz), alpha (8–15 Hz), beta (15–30 Hz), and gamma (30–60 Hz) the technical specifications of the signal sre as follows: "Signals are band-pass filtered between 0.05 and 200 Hz and then digitized at 1000 Hz with 16 bit (0.1 uV) accuracy." So kindly suggest me how can i extract these sub-bands using Wavelet Packet Decomposition. i have tried a lot but could not do the same. suggest me the relevant commands for this purpose.

[Rasa]

Hello, Did you get any solution on the problem ? I also want to know how to do this. Please kindly share.

Thanks

[kalarmago]

Hi, I am in the same issue, please, someone could help me and put some code (I am new in Matlab)?

Answer 1

[Abdulhakim Alezzi]

load eegdata.mat;

s=eegdata;

figure;p=plot(s);

title('EEG Signal')

fs = 500;

% Sampling frequency

N=length(s);

waveletFunction = 'db8';

[C,L] = wavedec(s,8,waveletFunction);

cD1 = detcoef(C,L,1);

cD2 = detcoef(C,L,2);

cD3 = detcoef(C,L,3);

cD4 = detcoef(C,L,4);

cD5 = detcoef(C,L,5); %GAMA

cD6 = detcoef(C,L,6); %BETA

cD7 = detcoef(C,L,7); %ALPHA

cD8 = detcoef(C,L,8); %THETA

cA8 = appcoef(C,L,waveletFunction,8); %DELTA

D1 = wrcoef('d',C,L,waveletFunction,1);

D2 = wrcoef('d',C,L,waveletFunction,2);

D3 = wrcoef('d',C,L,waveletFunction,3);

D4 = wrcoef('d',C,L,waveletFunction,4);

D5 = wrcoef('d',C,L,waveletFunction,5); %GAMMA

D6 = wrcoef('d',C,L,waveletFunction,6); %BETA

D7 = wrcoef('d',C,L,waveletFunction,7); %ALPHA

D8 = wrcoef('d',C,L,waveletFunction,8); %THETA

A8 = wrcoef('a',C,L,waveletFunction,8); %DELTA

Gamma = D5;

figure; subplot(5,1,1); plot(1:1:length(Gamma),Gamma);title('GAMMA');

Beta = D6;

subplot(5,1,2); plot(1:1:length(Beta), Beta); title('BETA');

Alpha = D7;

subplot(5,1,3); plot(1:1:length(Alpha),Alpha); title('ALPHA');

Theta = D8;

subplot(5,1,4); plot(1:1:length(Theta),Theta);title('THETA');

D8 = detrend(D8,0);

Delta = A8;

%figure, plot(0:1/fs:1,Delta);

subplot(5,1,5);plot(1:1:length(Delta),Delta);title('DELTA');

D5 = detrend(D5,0);

xdft = fft(D5);

freq = 0:N/length(D5):N/2;

xdft = xdft(1:length(D5)/2+1);

figure;subplot(511);plot(freq,abs(xdft));title('GAMMA-FREQUENCY');

[~,I] = max(abs(xdft));

fprintf('Gamma:Maximum occurs at %3.2f Hz.\n',freq(I));

D6 = detrend(D6,0);

xdft2 = fft(D6);

freq2 = 0:N/length(D6):N/2;

xdft2 = xdft2(1:length(D6)/2+1);

% figure;

subplot(512);plot(freq2,abs(xdft2));title('BETA');

[~,I] = max(abs(xdft2));

fprintf('Beta:Maximum occurs at %3.2f Hz.\n',freq2(I));

D7 = detrend(D7,0);

xdft3 = fft(D7);

freq3 = 0:N/length(D7):N/2;

xdft3 = xdft3(1:length(D7)/2+1);

% figure;

subplot(513);plot(freq3,abs(xdft3));title('ALPHA');

[~,I] = max(abs(xdft3));

fprintf('Alpha:Maximum occurs at %f Hz.\n',freq3(I));

xdft4 = fft(D8);

freq4 = 0:N/length(D8):N/2;

xdft4 = xdft4(1:length(D8)/2+1);

% figure;

subplot(514);plot(freq4,abs(xdft4));title('THETA');

[~,I] = max(abs(xdft4));

fprintf('Theta:Maximum occurs at %f Hz.\n',freq4(I));

A8 = detrend(A8,0);

xdft5 = fft(A8);

freq5 = 0:N/length(A8):N/2;

xdft5 = xdft5(1:length(A8)/2+1);

% figure;

subplot(515);plot(freq3,abs(xdft5));title('DELTA');

[~,I] = max(abs(xdft5));

fprintf('Delta:Maximum occurs at %f Hz.\n',freq5(I));

[Piyush Kant]

can you please explain the level selection for the same as Fs=500 thus making max fequency content 0-250Hz so according to me

d1=125-250 Hz

d2= 62.5-125 Hz

d3= 31.75-62.5Hz

d4 = 15.87 - 31.75Hz

d5 ~= 8-16 Hz

d6~= 4-8 Hz

d7=2-4 Hz

d8 = 1-2 Hz

Please correct me if i am wrong