Thomas Sailer wrote in a message to Mike Bilow:
> FSK and PSK are essentially the same thing as far as this issue
> goes, and you can regard FSK as a special case of PSK. I don't
> want to get into this issue in detail because experience has
> shown that it provokes religious arguments, but the math is
> clear.
TS> Eh? That sounds interesting, can you please provide the math?
Since phase and frequency are intensely interrelated, one can regard FSK as a
kind of limited-state PSK. When we talk about FSK in a ham radio context, we
usually mean two-state FSK with codes commonly known as "mark" and "space."
Although we do not ordinarily think of it as such, this sort of modulation is
mathematically isomorphic to two-state PSK. For a sufficiently randomized data
stream, it is even possible to use a generic PSK detector to receive FSK.
For reasons of engineering convenience, we do not actually design things this
way. However, from a theoretical point of view, the distinctions between FSK
and PSK are essentially engineering conventions.
The reason this becomes a religious issue -- and it always does -- is because
one eventually finds oneself asking the inherently unanswerable question, "What
did the electron know and when did it know it?
-- Mike
