AI4QJ wrote:
. . .
This is a bit philosophical for me but let me say that I believe that a
square wave is definitely the sum of superimposed odd harmonics in
accordance with Fourier. I believe each of the superimposed waves exists
independently. If you do not believe me, just ask anyway who lives next door
to a CB'er with a linear amp and transmits over modulated square waves (due
to saturating his amplifier). The square waves exist but so do the component
waves. I am not sure if this is related to what you are saying but it seems
to be the same thing.

This is indeed a philosophical question. A consequence of superposition
is that there's *no possible way* to tell if a particular square wave is
made from separately generated sinusoids, a single step, or combinations
of any of an infinite number of other possible periodic waveforms. With
the proper sorts of filters, you can take the square wave apart into any
of those infinite sets of functions, "proving" the "independent
existence" of each. Sinusoids are mathematically convenient, but they're
by far not the only choice.

Roy Lewallen, W7EL