I have a signal which consists of oscillations riding on square waves as shown in the image below. I wish to detect the time at which oscillatory events occur (as shown by the red star).
Each square wave is a different height and the oscillatory sequences riding on each sqaure wave are not identical. Here I have zoomed in on a small chunk of one oscillation.
A second order low-pass butterworth filter with cutoff at 500 Hz can be used to clean the data if this is a useful preprocessing step.
How can non-stereotyped oscillations be detected in a signal like this? Thanks!