If I had a signal that contained, say, a square wave and a sawtooth wave, how would I extract the frequency of the sawtooth wave without the higher harmonics that make the Fourier series converge on the sawtooth? I am writing a program that ideally would show the frequency of each signal in a song, but my problem is that the harmonics are showing up as well, which kind of gets in the way of the (fundamental?) frequency that I really want.
Esssentially, if I had a horn and a synthesizer playing single but separate notes, I want the frequency of those notes but not the higher harmonics that help you converge on the actual signal of each of those notes.