Please, I have to solve a problem and I really need some help.
I have to give an efficient method to consider a maximum amplitude as a starting point to consider as noise the whole spectrum below itself. Like on the example of the FFT below. Let's consider only on X axis, the red plot, the maxium peak is at a magnitude of 0.4, between 7 and 8 Hz. The next peak is at a magnitude of ~0.3, and the next after that is at ~0.25, and so on (in a decreasing order).
How can I give a consistent method to find the threshold between noise and real signal in terms of magnitude.
The perfect answer would be transforming it in a closed-loop control where I could go adding transfer functions with natural frequencies corresponding to those peaks until the response are no longer affected (for a unitary step). But for that, I would have to tell the system what is the magnitude of each peak. That's where I lose myself...
Thank you very much in advance.