How to analyze multiple amplitude modulated signals?
Well, you can of course instead of using the Discrete Fourier Transform as filter bank just employ bandpass filters to extract your individual tones.
(The DFT is really just a filter bank, if you think about it: it correlates an input sample vector with different complex oscillations. Which is convolution with their conjugate time inverse, which is a filter operation.)
This might be advantageous, since the filter shape of a DFT is inherently sinc-shaped, which I guess isn't quite close to what you want in terms of spectral sidelobes.
So, yeah, simply design a narrow low-pass filter, and shift it in frequency to the appropriate position. (Do that for every tone.).
If you've got many tones that you space on a regular grid, you might want to do a polyphase filter bank, but I'd consider this an &quot;advanced computational optimization that you probably don't need in your measurement process, as you don't care whether computations take a milli- or 100 microsecond&quot;.