On Sun, 17 Dec 2000 22:26:40 -0700 Garry <[EMAIL PROTECTED]> wrote:
> Yes, line of sight. Hmmm . . .
> <dream mode>
> A real challenge would be inventing some way
> of "broadcasting" such a light-spectrum signal.
> I suppose with a little thought (or a lot) one
> could devise a roughly circular array of emitters
> and receptors . . . although finding a way to
> multiplex that would require more engineering
> skill than I have . . . alternatively, each channel
> could simply be assigned its own frequency.
> </dream mode>
This is not just a dream. This has been done. The technology
is now decades old and it has found its way into many practical
applications. For example, the military uses focused beams of
modulated invisible IR light signals to transmit voice
communications over miles of "line of sight". The main advantage
of such a system is that you can broadcast in the clear because
the signals are highly unlikely to be detected even by a most
vigilant enemy. The basic technology, even the "nitty-gritty" of
it all, is not even classified. This is stuff that is well known
and well published. Anyone may have access to this kind of
material and research it. I have even seen electronic hobby project
books devoted to the subject. You can easily put together such a
system yourself.
All the best,
Sam Heywood
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