Help me understand my FFT output?

I have two signals and I want to know if they have a natural oscillation. But I don't know if I mistook the signal noise for oscillations and decided to get the fast Fourier transform of my signals.

Here is what I see,

I am not sure what is going on with the green curve.

Here is my code:

plot(AgeBins1,Xidx2,'g','DisplayName','Signal 2','LineWidth',2);

Xidx2f = fft(Xidx2);

plot(AgeBins1,Xidx2f,'g','DisplayName','Signal 1','LineWidth',2);

Answer 1

[Image Analyst]

Hard to say exactly but it looks like your green signal is sort of like a signal multiplied by a rectangular pulse or triangle wave. So the "true" signal will be convolved with something like a sinc function, which will give rise to the periodic ripples on your "true" signal.