Plot time domain frequency graph

Hello there! I have data from oscillator. It consists of 18000000 dots and looks like the graph from picture I've attached here. I need to plot time domain frequency graph, but because of oscillations I can't use 'findpeaks' or finding zeroes to calculate a period. How can I find a frequency and plot it in time domain?

Answer 1

[Abhishek Ballaney]

https://in.mathworks.com/help/matlab/ref/fft.html

[Roman Khatylenko]

Thank you, but as I know Fourier transform will give me magnitude of the signal on Y axis and frequency on X axis. Maybe I made a mistake in my question. Because I need frequency in Hz on Y axis and time on X axis. Sorry my English, if it confused You.