Suppose I have a real (physical) dynamical system with one capacitive sensor, and I also have the ability to extract data for this system in csv form. The system data output is shown below (graphs) for various sampling frequencies.
As the system is real time and its output depends on the immediate environment (temperature, pressure, etc..) I need to be able to determine if the sampling frequency is hitting any harmonics on-the-fly. All I have is data.
How, in general, can I determine resonant frequencies from data?