[NLRS] Rule 1.12 discussion

[Paul Beckmann]

I find the discussion interesting. I *certainly* agree that lightwave
communication should not be pushed off into its own separate contest -
yet. Maybe someday but not now. (For a parallel, I'm thinking of what
a 10Ghz and up contest would have been like 40 years ago. Not too many
entries, I would say.)

To guide my comments, I've been thinking of analogies to simple
transmission and reception systems. There has been, at least, some
sort of oscillating energy source that, ultimately, results in current
flow at some frequency. This can be modulated in many different ways
to impose information on the energy source, i.e., making it a
transmission. This can be as simple as switching it on and off to ...
you name it. There is then a means for taking this modulated energy
and "launching" it in a way that at least some of it, or some
byproduct of it, reaching a reception point.

Let's stop there for a minute. What would be the counterparts to these
elements of a typical transmitter in lightwave communication? An LED
and laser are sources of oscillating energy. Modulation can be had
through chopping/turning the source on and off (CW), modulating the
amplitude of the source (AM), and modulating the frequency of
oscillation (two different colored LEDs->FSK, for example). Launching
this modulated energy can be done with combinations of mirrors,
lenses, optical fibers, corner cubes, etc.

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My first comment is at odds with Donn's statement that

"Similarly, how about "monchromatic light," i.e., a single "color ?"
No argument that a flashlight
(or similar) does not qualify... "white" light is ALL COLORS, and
therefore cannot be coherent."

I want to point out the need for care in the use of the word "white".
To people in RF and audio design, "white" means a signal having equal
spectral power density over some range of frequencies. To people in
general, "white light" means "a light not perceived as having any
appreciable hue". Perceptual psychologists (my ancient forefathers)
discovered over a century ago that "white light" can be made up of a
mixture of 3 or 4 very narrowband light sources. I would argue that
light "perceived as white" could be assembled from three laser beams,
each quite coherent by themselves, and that their mixture could have a
predictable phase relationship to each other, although not one that
was fixed.

Taking the definition by w9Ray of coherent light as:

"light in which the electromagnetic waves maintain a fixed and
predictable phase relationship with each other over a period of time."

in some sense, "white" light can be coherent, if mixtures of coherent
light are considered to be coherent as well.

So, "white" light DOES NOT necessarily contain all colors and might
theoretically be coherent, if I understand w9Ray's definition
correctly.
--------------

I'm wondering where all this discussion of "fixed
frequency/monochromatic/coherent" light came from historically. How
does modulation come to play a role? In a particular setup, how could
you tease apart the separate contributions of LED/laser and modulation
scheme to the non-monochromatic nature of the output signal, with only
the output to observe?

Why is electromagnetic radiation in this particular band subjected to
more stringent rules than lower bands? I don't believe any of us use
crystal-controlled IF rigs on our microwave transverters. They aren't
"monochromatic", even in CW, and aren't required to be.

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There are a whole collection of exotic optical modulation schemes and
elements to support them out there that are virtually untapped by hams
to date. There are a whole collection of exotic optical "antenna"
(lens, mirror, etc. combos) out there that are untapped as well. If a
ham wants to use a flashlight and their hand to send morse code and
the "receiver" wants to look through binoculars and decode, why care?
"Electronic detection"? Why? What defines "electronic"? If I have an
optical device that converts light to sound directly through some
solid-state effect, should it be disqualified as "non-electronic"? (If
you think I'm being "pie in the sky", I'll send you an article from a
recent issue of the Proceedings of the National Academy of Science in
which single living cells from a vertebrate retinal are *aligned and
centered" using NOTHING MORE than pressure generated by shaped IR
light.)

I can here someone saying long ago: "If there isn't ladder line or
coax between the antenna and the equipment, the equipment isn't a
radio!" I bet waveguide folks had a long battle to be recognized as
"real radio" in some quarters.

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I'd like to see *less* regulation and *more* experimentation!

73
--Paul, wa0rse