Hi Pablo:
I started to read:
CTRI-Scope.pdf <http://www.ohwr.org/attachments/764/CTRI-Scope.pdf>
(323.2 kB) Pablo Alvarez, 26/09/2011 18:46
but without a glossary to decode all the abbreviations or acronyms it's
very difficult to really understand what's going on.
Is there an introductory document that describes the experiment and
defines the terms used?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.End2PartyGovernment.com/
pablo alvarez wrote:
Hi guys,
Here you have the reports on the CERN's timing chain.
http://www.ohwr.org/documents/111
Questions are welcome!
pablo
On Mon, Sep 26, 2011 at 2:46 PM, Joe Gwinn<[email protected]> wrote:
At 6:56 AM +0000 9/26/11, [email protected] wrote: (really Javier
S)
Date: Mon, 26 Sep 2011 08:56:12 +0200
From: Javier
Serrano<javier.serrano.pareja@gmail.**com<[email protected]>
To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] Fast than light neutrino
Message-ID:
<CAHBYzfTSx=**jMKg218Sy6F9ji93OAht2=60w9_**
[email protected]<[email protected]>>
Content-Type: text/plain; charset=ISO-8859-1
[snip]
>
I did not express myself correctly. We know how to do accurate two-way
sync
over a few km of fiber. See e.g.
http://dl.dropbox.com/u/**13409775/pac2011/WEOAN1.pdf<http://dl.dropbox.com/u/13409775/pac2011/WEOAN1.pdf>or
http://dl.dropbox.com/u/**13409775/wrapper.pdf<http://dl.dropbox.com/u/13409775/wrapper.pdf>(our
contribution to the CLIC
Conceptual Design Report).
Thanks for the reports.
What is new for us is going through more than
1000 km of fiber (only neutrinos have the luxury of going in a straight
line
through the crust of the Earth, 732 km). I wonder who one calls for fibers
and also more technical things like optical amplifier technology with
typical ranges, etc. What I gather from the discussion so far is that 100
km
is within reach of available optical transceivers. I wonder how far one
can
go with EDFAs.
EDFAs can easily achieve 10 dB or running closer to the edge 20 dB of gain,
all with no electronics delay, but EDFAs are quite noisy, so there is a
tradeoff to be made.
EDFAs are inherently bidirectional, although they usually contain an
optical circulator to make them unilateral. But it would not be hard to
make EDFAs that amplified in one direction for one wavelength, and in the
opposite direction at a different (but nearby) wavelength.
And one can also have a command wavelength, to allow for commanding of
direction reversals and the like, so the fiber companies involvement is
limited to hosting and installation of equipment.
One thing we could do is establish a fiber link between METAS
in Bern and CERN, and then look for a good metrology place in Rome (the
national one in Italy is in Torino I believe) and have a link between them
and Gran Sasso. Then we could use their UTC data sets to establish a paper
link between CERN and Gran Sasso which would be independent of the current
link.
Why do all that, versus just running an amplified fiber between CERN and
Gran Sasso? Two links are likely to be twice the trouble and error.
Joe Gwinn
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