[time-nuts] Smart fiber-optic cable ( a reference to Hp's smart clock )

[Robert Darlington]

My gut feeling is that it's pretty easy to measure propagation delay over
fiber, especially if it's long.  Is there some reason you can't just bounce
light off the far end of the cable and measure round trip time?  I don't
know the electronics involved in signaling with fiber but surely you could
have a 2nd piece of fiber closely coupled /  run along side the  data cable
with a mirrored end and just measure it with a TDR.

Of course, I've never tried this and there might be some major engineering
challenges.  Any thoughts on this?

-Bob


On Mon, Feb 4, 2013 at 3:39 PM, mike cook <mc235960 at gmail.com> wrote:

> I think someones on it.
>
> check out
> <http://www.ospmag.com/issue/article/Timing-Is-Everything>
>
> Le 4 févr. 2013 à 23:09, Stanley a écrit :
>
> > If a fiber-optic cable had temperature sensors either installed with or
> embedded inside of this could make for better modeling changes in delay
> making more accurate transfer of time and frequency possible. With fiber to
> tower installs now under way to provide more data at cell towers why not
> backup GPS frequency and time transfer with the same medium ? Would this
> also increase the data rate of the cable ? That is faster rates due to the
> better timing uncertainty.
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