[time-nuts] Optical Distribution of 1PPS and IRIG

Chris Albertson albertson.chris at gmail.com
Sun Jul 13 14:29:00 EDT 2014

What accuracy requirements do you have?    Do you have a requirement
to measure and test your installation?   Testing likely means you will
have to "round trip" the signal.  The round trip doubles the cost but
I don't see how to avoid it unless you already have accurate time at
both ends and if you have that you don't need the cable.

The best way to transfer time is the "common view" method where each
end looks at the same source.   GPS allows this now

I still bet that even with free cable a gps recover in the second
building gives better performance at lower cost.  I could be wrong
you'd just have to add it up both ways. That is the BEST way to solve
many engineering problems:  Do several different designs then compare
them.  Don't get locked in to one thing early.

But no one can suggest anything specific without performance requirements.

On Sun, Jul 13, 2014 at 10:39 AM, Martin A Flynn <maflynn at theflynn.org> wrote:
> Hi Chris,
> Timing source is a SyncServer 200 with the rubidium option.    The
> inter-building fiber is already  budgeted as part of the IT and telecom
> portion of the project.   It adds no cost to the project to use it other
> then the optical transceivers.
> That is where i need help - selecting the best product (in terms of
> cost/performance)
> Martin
> On 7/13/2014 1:07 PM, Chris Albertson wrote:
>> What accuracy requirements do you have.  This could be easy or impossible.
>> Don't spend to much money distributing 1PPS because you can have it
>> any place you want for the cost of a GPS receiver.  A second GPS
>> receiver is likely cheaper than the cost of 120 meters of cable plus
>> the cable drivers and receivers.  Even if you build the cable system
>> you'd need to test it which adds more time and cost.  GPS is so cheap
>> you can place them where needed.
>> On Sun, Jul 13, 2014 at 8:19 AM, Martin A Flynn <maflynn at theflynn.org>
>> wrote:
>>> I am working on a project where I need to transfer 1PPS approximately 120
>>> meters between buildings.    I cam borrow a pair of 62.5 fibers from
>>> IT/telco to do so.
>>> Playing cost / performance against one another, I am looking for a
>>> solution
>>> somewhere in the middle that does not requires SM-28 single mode fiber)
>>> Martin


Chris Albertson
Redondo Beach, California

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