Richard Clark wrote:
Several but closely related questions:
What separates "effect" from "no effect?" (They are, afterall, a
rather strict binary outcome.)

It is a rather strict binary outcome when we are
discussing coherent vs mutually incoherent waves
as Walt obviously was. The gray area in between
to which you are alluding is called "partial
coherence". It is the region between "coherent"
and "mutually incoherent" which makes it three-state,
not binary, much like a logic 0 vs a logic 1 with
an in between region.

We generally would not have to worry about "partial
coherence" in a transmission line but if you want to
nit-pick that subject on rraa, be our guest.
--
73, Cecil http://www.w5dxp.com