[sdiy] Harmonic content of the "sigmoid" half-sine wave

[Scott Nordlund]

> I think it would be safe to say that the period of repetition is equal to
> the least common division of all the wave form periods, that is to say it
> would only repeat on the lowest number of full cycles for all the waves.

Right.

> It is also my understanding that if you mix 2 sine waves you get four
> frequencies out, the original frequencies, the sum of the frequencies, and
> the difference of the frequencies. With each additional sine wave added you
> get the same effect interacting with each of the other frequencies.

I think you need some sort of nonlinearity for the difference tones to come out.    The ear (and/or brain) isn't necessarily perfectly linear though.  A ring modulator replaces the original frequencies with the difference tones.

> So is the suggested fundamental not there, or is it created by the total
> interaction of the original sine waves, their least common fundamental
> frequency, ( even though not present in the generation of the waveform )
> and represented by the resulting wave form?

We can hear the fundamental, it isn't actually represented in the signal, but I believe it's the result of our perception

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