MATLAB: Filtering ECG signal using 4th order low pass filter

butterworth filterecg filterlow-pass filter

hello friends, i have written matlab code for 4th order butterworth filter of 70 hertz along with poles, zeros, transfer. Now, how can i apply this designed filter on an ecg signal? thanks. i am sharing my code here. clc; wc= 70; N= 4; K= 2.575; for k= 0:N-1 Sk(k+1)= wc*exp(1i*(pi/2))*exp(1i*(2*k+1)*(pi/(2*N)));
    end
    [NUM,DEN]=zp2tf([],Sk,K);
    b0=DEN(end)*K;
    Hs=tf(b0,DEN);
    figure();
    freqs(b0,DEN)
    figure();
    plot(Sk./10^2, 'x')
    xlim([-10,10]);
    title('Pole placement in s-plane')
    %
      for x = 1:10
          disp(x)
      end
    [NUM,DEN]=lp2lp(NUM,DEN,wc);
    fs=1000;
    [NUMd,DENd]=bilinear(NUM,DEN,fs);
    disp('NUMd='),disp(NUMd')
    disp('DENd='),disp(DENd')
    [Hd,wd]=freqz(NUMd,DENd);
    Magd=abs(Hd);
    subplot(2,1,1);
    plot(wd/pi,Magd);
    grid on;
    title('Digital Lowpass Butterworth Filter');
    ylabel('Amplitude response')
    axis([0 0.2 0 1])
    subplot(2,1,2);
    plot(wd/pi,angle(Hd));
    grid on;
    axis([0 0.2 -200 200])
    ylabel('Phase response')
    xlabel('Frequency,[unit of pi]')

Best Answer

You can try in following way- For detail visit here
tic;
while toc<t %mention time of the signal to be observed here e.g. t=20,30 etc
    filtered_ECG_Signal=mgd(Original_ECG_signal); %make the designed filer as a custom function or you can apply directly too.
    TS(Original_ECG_signal,filtered_ECG_Signal);
end
% Finalize
release(TS)
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