On Mar 6, 3:35*pm, Cecil Moore wrote:
What you seem to be missing, Tom, is that if the two signals
are not coherent, interference is not possible. Since we are
discussing interference effects between obviously coherent
forward and reflected waves, your observation seems to be a
moot point.

For instance, if the forward and reflected traveling waves
in Roy's "Food for Thought" page are replaced by two sources
that differ by 30% in frequency, there is no way for that
entry in his chart to reach the 400 watts dissipated in the
source resistor.

How coherent do the two signals have to be for interference to
occur?

You say that when the sources are coherent, interference occurs
but when the frequency differs by 30% it does not.

What happens if one of the sources has just a bit of phase noise,
or the frequency wanders just a bit, or is just offset a bit?

How much of a difference does there have to be for interference
to stop? What is the threshold? Phase noise? Wander? Offset?

And is it the mechanism that creates interference that stops working
once the threshold is crossed?
Or does the mechanism still work, but we just no longer call the
result interference? Why do we stop calling it interference once
the threshold is crossed?

What is the mechanism that creates the effect we call interference?

...Keith