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How to compute the moving average of a signal with 6-hour window length and shifted 15 min at a time?

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Hello,
I am working on ECG signal and I want to determine the HR.
How to compute the moving average of a signal with 6-hour window length and shifted 15 min at a time?
Sampling frequency is 200.
Thank you

Accepted Answer

Dimitris Kalogiros
Dimitris Kalogiros on 22 Sep 2019
Hi Mohanad
Bellow, you will find an example, where a moving average corresponding to a 6h window, is applied upon a signal taken within an interval of 24h with Fsampling=200Hz
clearvars; close all; clc;
%% input data
Fs = 200; % 200 Hz sampling frequency
time = 0:(1/Fs):(24*3600-1); % data collected within 24 hours
data = sin(2*pi*(1/2E5).*time)+0.2*randn(size(time)); % an example of input data: a sine with some noise
%% averanging
Kstep = (15*60)*Fs; % step of 15 minutes
Kwindow = (6*3600)*Fs; % aneranging window is 6 hours
meanData=[]; meanTime=[];
for k=1:Kstep:length(data)-Kwindow
dataWindow=data(1:k+Kwindow);
meanData=[meanData mean(dataWindow)];
meanTime=[meanTime time(k+floor(Kwindow/2))];
end
figure;
%mean values are depocted at the middle of their corresponding 6h window
plot(time, data); hold on;
plot(meanTime, meanData, '-*'); zoom on; grid on;
xlabel('time'); ylabel('data values');

  1 Comment

Mohanad Alkhodari
Mohanad Alkhodari on 27 Sep 2019
I tweaked this code and it worked perfectly.
Fs = 200; % 200 Hz sampling frequency
time = ((0:17280000)/Fs)'; %24 hours in seconds
Kstep = (15*60)*Fs; % step of 15 minutes
Kwindow = (6*3600)*Fs; % averaging window is 6 hours
meanData=[];
meanTime=[];
k_old = 1;
for k=1:Kstep:length(data)-1
dataWindow=data(k_old:k+Kstep);
meanData=[meanData mean(dataWindow)];
meanTime=[meanTime time(k+floor(Kstep/2))];
k_old = k+Kstep;
end
figure;
%mean values are depocted at the middle of their corresponding 6h window
plot(time, data); hold on;
plot(meanTime, meanData, '-*'); zoom on; grid on;
xlabel('time'); ylabel('data values');

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More Answers (1)

Steven Lord
Steven Lord on 22 Sep 2019
Use movmean with a datetime or duration SamplePoints input. Specify the window using a duration array.

  1 Comment

Mohanad Alkhodari
Mohanad Alkhodari on 27 Sep 2019
I did not get this.
The signal is in samples, I use movemean but it only provides the window length as inputs.
How to use SamplePoints for steps of 15 minutes each?

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