How can I plot BPM over time using a UTC start time in an epoch.txt file?

At the moment, I have BPM plotted against the duration of my ECG device's recording (~90 mins). What I'd like to do is to use a start time I have in UTC from an epoch.txt file outputted by the ECG device (e.g 07:55:14) to be able to plot BPM across the actual time during the session (e.g 07:55:14 - 09:25:14). I'd like to do this so I can identify the time in UTC of peaks in BPM and to average BPM during a period of the session I only readily know in UTC.

I realise I could work out the actual time of a peak by using the time elapsed on my current plots along with the start time in the epoch.txt files but I have lots of ECG data across many sessions which vary in duration with different start times so I'd like to save myself some grief!

I would also like to ultimately automate this process so any help or tips as to how to automate this into a script would be very appreciated too.

Thank you!

Answer 1

[VINAYAK LUHA]

Hi Molly,

I understand that, you have multiple 90 minutes BPM data and their initial UTC start time stored in a file named "epoch.txt". Your objective is to generate a plot depicting BPM against UTC time.

Here is code snippet to convert the time axis of your BPM plot to actual UTC time-

% Read the start time and date from the epoch.txt file
fileID = fopen('epoch.txt', 'r');
startDateTimeStr = fgetl(fileID);  
fclose(fileID);

% Convert start time and date to MATLAB datetime format
startDateTime = datetime(startDateTimeStr, 'InputFormat', 'dd/MM/yyy HH:mm:ss');

% Duration of the ECG recording (e.g., 90 minutes)
duration = minutes(90);

% Calculate end time
endDateTime = startDateTime + duration;

% Create a time vector representing the actual UTC time during the session
timeVector = startDateTime:seconds(90*60/5399):endDateTime;  % Adjust the time step to match the size of the data

% Plot BPM data against timeVector
plot(timeVector, bpmData);
xlabel('Time (UTC)');
ylabel('BPM');
title('ECG BPM across the session');

Further, you can automate this process for multiple sessions by encapsulating the code in a function and looping through the session files.

Additionally, you can refer to the following documentations for more details about the function used above -

• https://www.mathworks.com/help/matlab/ref/fopen.html
• https://www.mathworks.com/help/matlab/ref/fgetl.html
• https://www.mathworks.com/help/matlab/date-and-time-operations.html

Hope this resolves your query.

Regards,

Vinayak Luha