MATLAB: Calculating BPM – from PPG signal

arduinobpmheart rateppg

Hi everyone,

I've been able to create a script that reads heart rate – displaying the value in real time on a graph.

Now i need to calculate the number of peaks in the graph and work out the BPM

Any simple script solution?

Any help will be most appreciated! Thanks!

Best Answer

Check out the findpeaks command. Alternatively (if you do not have access to the Signal Processing Toolbox) you could do a Fourier Transform and look at the dominant frequency components.

Related Solutions

MATLAB: How to find average heart beat using fast Fourier transform function

I'm going to give a solution that says your 3000 data points represent a timeseries of 6 seconds. The code can be modified if that assumption is incorrect. Just have Fs=3000/elapsed-time-in-seconds

X = dlmread('ECG.csv');
% assumed that the 3000 points are 6 seconds of data...?
Fs = 3000/6; %  [samples/s] sampling frequency 
T  = 1/Fs;      % [s] sampling period       
N  = 3000;       % [samples] Length of signal
t  = (0:N-1)*T; % [s] Time vector
deltaF = Fs/N; % [1/s]) frequency intervalue of discrete signal
figure('color','white','position',[70 100 600 900]); 
subplot(3,1,1);
plot(1e3*t,X)
title({'Heartbeat data'})
xlabel('t (milliseconds)')
ylabel('X(t)')
% compute the fast fourier transform
Y = fft(X);
% manually shifting the FFT
Y = abs(Y/N);
Amp = [Y(ceil(end/2)+1:end)' Y(1) Y(2:ceil(end/2))']';
if (mod(N,2) == 0)
sampleIndex = -N/2:1:N/2-1; %raw index for FFT plot

else
sampleIndex = -(N-1)/2:1:(N-1)/2; %raw index for FFT plot
end
subplot(3,1,2);
plot(deltaF*sampleIndex, Amp);
hold on;
idx = find(Amp > 3.5);
idx(sampleIndex(idx) < 0) = [];
plot(deltaF*sampleIndex(idx), Amp(idx), '+');
for k = 1:length(idx)
    if (idx(k) > (N-1)/2 && Amp(idx(k))>3.5)
        h = text(deltaF*sampleIndex(idx(k)), Amp(idx(k))+0.15,...
            ['f=' num2str(deltaF*sampleIndex(idx(k))) ' Hz']);
        set(h,'rotation',90)
    end
end
xlabel('Frequency [Hz]');
ylabel('Amplitude');
title(['Heartbeat = ' num2str(deltaF*sampleIndex(idx(1))) ' Hz = ' ...
    num2str(60.0*(deltaF*sampleIndex(idx(1)))) ' BPM']);
xlim([0 max(deltaF*sampleIndex)/4]);
subplot(3,1,3);
half_f = deltaF*(0:(N/2));
plot(fftshift([half_f -fliplr(half_f(2:end+mod(N,2)-1))]), ...
    abs(fftshift(Y)/N));
xlabel('Frequency [Hz]');
ylabel('Amplitude');
title('Using fftshift');

This yields:

MATLAB: How can i change the x-axis to read real time

you may consider axis shifting x1, dx y1 y2 constant axis([x1 x1+dx y1 y2]) and apply drawnow after each plot so the graph is updated

The answer to this question may seem to answer your query https://www.mathworks.com/matlabcentral/answers/330234-how-to-make-a-moving-graph-for-a-real-time-signal-along-the-x-axis#answer_259067

Best Answer

Related Solutions

MATLAB: How to find average heart beat using fast Fourier transform function

MATLAB: How can i change the x-axis to read real time

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