MATLAB: How to detect variations in data

Question

Hello everyone,

I would like to determine the location at which there is data variation (like the highlighted points in the attached image).

Kindly find the attached code + .mat file.

Each sub-plot represents a variable on y-axis and the time on x-axis. Usually, the variation appear in several variables (plots) like this one.

Could you suggest the best method to do so?

and How can I determine the starting and ending points of that variation?

I appreciate your help.

Answer 1

You might try movstd() to do a sliding window standard deviation. Then threshold it to find elements where the standard deviation is what you deem "high". See attached code where I did it for your "B" signal. Adapt it to do any other signals you want.