I have a signal's spectrogram and frequency spectrum (which, if i'm not mistaken, is its the signal's fourier transform) as given below:
I understand that the spectrogram plots the frequency (y-axis) vs time (x-axis) and that the colors represent the amplitude. I also understand the frequency spectrum as the plot of amplitude vs. frequency. But I'm not quite sure how to produce one graph from the other. Since there is no time axis on the frequency spectrum, surmise that it is impossible to create the spectrogram from a frequency spectrum. It seems plausible to derive the frequency spectrum from the spectrogram, but I'm not quite sure how to remove the time parameter.
Any help with this would be greatly appreciated.