"Bill Sohl" wrote in message hlink.net...
"N2EY" wrote in message
...
In article . net, "KØHB"
writes:

"N2EY" wrote



But in fact, the mode used in practically all fiber optic
communications
is
simple on-off keying of a "carrier".

Very similar, in fact, to landwire telegraph practice, speeded up and
automated, and using photons instead of electrons.

Jim, your credibility is fast evaporating!!!!!! This is the most wildly
stretched and tortured analogy to hit rrap since FOREVER!

How so?

The old original landwire telegraph used a single (usually iron) wire and
on-off keying of an electric current. Fiber optics uses a glass fiber and
on-off keying of an beam of light, usually from a laser. Both sent
messages by
time-domain multiplexing.

Actually, in really high speed optical equipment it is both
time domain and wavelengths/frequency (sometimes called color) domains.

Multiple "carriers" (different light wavelengths) on the same fiber,
right? Kinda like multiple telegraph carriers of old.

But isn't the basic modulation scheme still on-off keying of the
light, rather than shifting its color or phase?

There is equipment out there that operates at 1.6 Terrabits/sec.

lessee...10^12 bits/second...that's more than all of the RF spectrum
normally used for radio, right? And that's through *one* fiber that's
immune to EM fields, weather, ionospheric and tropospheric
propagation, EMI and almost everything else except shovels.

Now that's cool.

But it does have a downside. It permits a significant number of US
jobs to be outsourced to places like India (or anywhere else that has
a significant English-speaking population).

73 de Jim, N2EY