Please bear with me, I know some of you will scoff but I have looked on Wiki and in various literature (see below) and can't quite get a handle on a few things.
I am a general business programmer, in so much as I very rarely perform any complicated maths/physics related programming.
Anyway, whilst at Uni and studying Computer Networks I was introduced to Fourier analysis down at the physical level. I had trouble understanding the actual application of the analysis (as described in A Tannenbaum's Computer Networks) he just throws in some equations and asserts that they are used to approximate a signal modulated to carry data. I could also never understand the relationship between harmonics and the signal.
Lastly, in summary, is this analysis used to pick up from a physical medium, ie re-construct, retrieve the data initially sent.