Monday, February 15, 2016

Matlab code to study the EEG signal






ECE/BIOM 537: Biomedical Signal Processing
Colorado State University                                                           
Student: Minh Anh Nguyen
Email: minhanhnguyen@q.com




1.      This homework will demonstrate EEG signal processing techniques and interpretation. A 10 s signal, with sampling rate of 512 samples per second, has been provided. The signal was monitored and obtained using the C4 and P4 electrodes, and is a differential voltage signal (Image (Links to an external site.) ).
The signal in the attached file, 'EEGsig', will be used for parts a through d, while 'EEGsig_wander' will be used in part e.  Use two of the methods discussed in class to estimate the power spectral density of the 10 s epoch, and compare them with some discussion.  



a)  Estimate the dominant frequency region in the EEG signal using the PSD estimates. Given your knowledge of the frequency bandwidths in EEG signals and the location of the electrodes, what type of wave might this signal represent? What might it indicate?

The dominant frequency is 8.3Hz, which indicates that the EEG signal is for Theta wave (8-13Hz).
The maximum power occurs at 8.3 Hz
The power estimate is 0.67

b)  Design a low-pass filter to be used on the EEG signal. Choose a cut-off frequency that retains the energy in the dominant frequency region found in part b. Discuss your choice of cut-off frequency and how well your filter worked.
The cut-off frequency is 175Hz; because the dominant frequency is 8-10 Hz and the plot becomes flat after 175Hz.  After 175Hz signal has a lot of noise.
Low-pass filters will pass low frequencies without change, but attenuate (i.e. reduce) frequencies above the cutoff frequency

c)      Plot the low-pass filtered signal using the filter you designed in part c, then comment on the new signal.


e)      The original signal had low-frequency artifacts (baseline wander, etc) that were removed for the signal in parts a-d. Using EEGsig_wander, find a way to remove the baseline wander to approximate EEGsig. Discuss the method used and how well it worked. You can quantify the difference using a metric like mean squared error, if you prefer

. 









Matlab code:
ECE/BIOM 537: Biomedical Signal Processing
                                                               Colorado State University                                                           
Student: Minh Anh Nguyen
Email: minhanhnguyen@q.com


 l   close all; clear all; clc;
fs = 512 % fs — Sampling frequency, positive scalar. Sampling frequency, specified as a positive scalar. The sampling frequency is the number of samples per unit time. If the unit of time is seconds, the sampling frequency has units of hertz.
T = 1/fs;% sampling rate or frequency
load('J:\BIOM_Signal_processing\HW10\hmwk_EEGs') % contains eeg1 and fs
N =length(EEGsig); ls = size(EEGsig); % find the length of the data per second
tx =[0:length(EEGsig)-1]/fs;% Make time axis for EEG signal
fx = fs*(0:N/2-1)/N;   %Prepare freq data for plot
figure; subplot (211), plot(tx,EEGsig); xlabel('Time (s)'), ylabel('Amplitude (uV)'), title('Original EEG signal'); %EEG waveform
subplot(212), plot(tx,EEGsig);
xlabel('Time (s)'), ylabel('Amplitude (uV)'), title('Zoom into original EEG signal at 1 to 2 seconds'), xlim([1,2]) % Used to zoom in on single ECG waveformfigure;
%The mean of the PSDs of xl
mean_EEGsig = mean(EEGsig);
max_value=max(EEGsig);
mean_value=mean(EEGsig);
threshold=(max_value-mean_value)/2;

%Estimate the power spectrum of the 10-s epoch by computing the periodogram
%% this method is slide the window through the entire data at every 1/2 second, calculate the frequency, average it.
[p,f] = pwelch(EEGsig,hamming(fs),.5*fs, 2*fs,fs); %%
figure; subplot(421), plot (f,10*log10(p),'r'); xlabel('freq (hz)');
ylabel('PSD Amplitude'); title('Power SPectral Density via Welchs method and hamming window');grid on; xlabel('freq (hz)');ylabel('PSD Amplitude (dB)');
subplot(422), plot (f,10*log10(p),'g'); xlabel('freq (hz)');ylabel('PSD Amplitude (dB)'); title('Power SPectral Density via Welchs method zoom in at 60 hz'); xlim([0,60]);grid on;

x= EEGsig;
[pxx,f] = periodogram(EEGsig,hamming(length(x)),length(x),fs,'power');
[pwrest,idx] = max(pxx);
fprintf('The maximum power occurs at %3.1f Hz\n',f(idx));
fprintf('The power estimate is %2.2f\n',pwrest);
subplot(423), plot(f,10*log10(pxx));title('Power SPectral Density via periodogram method and hamming window');grid on; xlabel('freq (hz)');ylabel('PSD Amplitude (dB)');
subplot(424), plot(f,10*log10(pxx));title('Power SPectral Density via periodogram method and hamming window zoom in at 60Hz');grid on; xlabel('freq (hz)');ylabel('PSD Amplitude (dB)');xlim([0,60]);
%% low pass filter
lpfLength=127; % Order/Number of Filter coefficients
fc = 30; %% cutoff frequency
Wn=(2*fc)/fs; h1=fir1(lpfLength,Wn);
figure; plot(h1);xlabel('Time in Seconds'); ylabel('Magnitude'); title('Low-pass filter');
fi = filtfilt(h1,1,EEGsig);
figure; plot(fi); title ('filtfilt');
%Compute the Fourier transform
Tr1 = conv(EEGsig,h1);
figure; plot(Tr1);


Click on the link below to download the EEG raw data:
  hmwk_EEG.mat file




34 comments:

  1. This comment has been removed by the author.

    ReplyDelete
  2. Thank you very much for providing help to understand analysis of EEG signal.

    please provide the code for
    splitting or classification of EEG for getting frequency band in EEG signals like DELTA (0.5 to 4 Hz) THETA(4 to 8 Hz), APLA( 8 to 12 Hz),BETA( 12 to 30 Hz),GAMMA( >30 Hz)

    I am looking forward to a positive response from you.

    THANK YOU SO MUCH FOR YOUR TIME AND CONSIDERATION

    ReplyDelete
  3. can u pls mail me the load file or raw signal file.('J:\BIOM_Signal_processing\HW10\hmwk_EEGs')
    minkscdl@gmail.com

    ReplyDelete
    Replies
    1. https://drive.google.com/file/d/0B8b2y53z8_NsTjlac2hDYXh6Ylk/view

      Delete
  4. atleast tell how u have taken variables in the raw data file .

    ReplyDelete
  5. hi i would like to see your raw eeg signal file so that i may try to use your codes. this is my email address. aaronkarlo_maranan@yahoo.com
    thank you.

    ReplyDelete
  6. can u mail me your eeg raw file signal
    mail id-purushotamdeora@gmail.com

    ReplyDelete
  7. Hi. I want matlab codes about analysis eeg with CCA and MEC algorithm and fond eeg signal labels.plz help me.tkanks

    ReplyDelete
  8. Hi. I want matlab codes about analysis eeg with CCA and MEC algorithm and fond eeg signal labels.plz help me.tkanks

    ReplyDelete
  9. hi i would like to see your raw eeg signal file so that i may try to use your codes. this is my email
    address.
    nehad19944@gmail.com
    J:\BIOM_Signal_processing\HW10\hmwk_EEGs

    ReplyDelete
  10. hi i would like to see your raw eeg signal file so that i may try to use your codes. this is my email
    gahan97@gmail.com

    ReplyDelete
  11. hi i would like to see your raw eeg signal file so that i may try to use your codes. this is my email saurabh.telharkar@gmailcom

    ReplyDelete
  12. Hi thank u very much for this code.
    can u pls mail me the code for epilepsy classification using eeg signals.
    I am looking forward to a positive response from you.
    thanks alot again and this is my email:
    faris2205@gmail.com

    ReplyDelete
  13. i need raw eeg data. please send to me in seethalvs93@gmail.com

    ReplyDelete
  14. Hi thank u very much for this code.
    can u pls mail me the code for epilepsy classification using eeg signals.
    I am looking forward to a positive response from you.
    thanks alot again and this is my email:
    faris2005@gmail.com

    ReplyDelete
  15. can someone help me in matlab coding to filter original wave for my channel?

    ReplyDelete
  16. i can not run this code. shows error in line 4. please sone one tell me what can i do?

    ReplyDelete
  17. Hai.. I need matlab code for preprocessing of EEG signal.. can someone send me MATLAB code.. email id- monicasweety39@gmail.com

    ReplyDelete
  18. Hello currently working on EEG Based Human stress detection could any one share the database used and the MATLAB Code for refernce .

    ketkigijare@gmail.com

    ReplyDelete
  19. i want EEG database for Alzheimer's diseases please help me

    ReplyDelete
  20. can someone provide me the P300 speller matrix BCI analysis matlab code please?

    ReplyDelete
  21. I have my own .mat file but i am not sure what I am supposed to replace EEGsig with, if you could please explain how you got that array of numbers

    ReplyDelete
  22. Congrats on your post. Everything works like a charm. Thank you. Excellent work. All the best.

    ReplyDelete
  23. Hi. Anyone have MATLAB code for preprocessing of EEG data in EDF format. can anyone send me the code pliz.
    s11101819@student.usp.ac.fj

    ReplyDelete
  24. hii,i am new this topic. I need matlab code for preprocessing of EEG signal. please provide the code for
    splitting or classification of EEG for getting frequency band in EEG signals like DELTA (0.5 to 4 Hz) THETA(4 to 8 Hz), APLA( 8 to 12 Hz),BETA( 12 to 30 Hz),GAMMA( >30 Hz).can anyone send me the code plz
    nparvin698@gmail.com

    ReplyDelete
  25. Hi..i want license agreement of eeg signal that are converted into scale from 1 to 100

    ReplyDelete
  26. This comment has been removed by the author.

    ReplyDelete
  27. Hi.. I'm in a need of MATLAB Code for CCA on EEG signals. I'll be grateful if anyone can provide this.

    Thanking you in advance,
    Vidyasri.

    ReplyDelete
  28. Hi, can you please mail me your EEG raw file signal
    MAIL ID : dominat865@gmail.com

    ReplyDelete
  29. Можете ли вы отправить мне свой сигнальный файл EEG
    по электронной почте astaninnamargo@rambler.ru

    ReplyDelete
  30. can u mail me your eeg raw file signal
    mail astaninnamargo@rambler.ru

    ReplyDelete