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

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

[KALYAN ACHARJYA]

I am working on ECG signal and I want to determine the HR.

Is this here ?

[Mohanad Alkhodari]

No this is not the same

am working on a different thing

Answer 1

[Dimitris Kalogiros]

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');

[Mohanad Alkhodari]

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');

Answer 2

[Steven Lord]

Use movmean with a datetime or duration SamplePoints input. Specify the window using a duration array.

[Mohanad Alkhodari]

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?