[time-nuts] Optical transfer of time and frequency

[Michael Wouters]

So why not do White Rabbit free space ?

Cheers
Michael

On Sat, Apr 30, 2016 at 4:04 AM, Paul Boven <p.boven at xs4all.nl> wrote:
> Hi everyone,
>
> On 04/29/2016 03:28 PM, Magnus Danielson wrote:
>>
>> Phase/time transfer over fiber is shaping up, but White Rabbit is
>> starting to grow up and more reports for long distances is showing up.
>> ETFT is one of the placces to check for reports.
>
>
> And the White Rabbit workshops, with the presentations online:
> http://www.ohwr.org/projects/white-rabbit/wiki/Mar2016Meeting
>
> I happen to be working on time transfer via White Rabbit. The White Rabbit
> standard proscribes the use of 1000Base-Bx10 (10km reach bi-directional)
> SFPs, but it turns out to work just fine with longer reach SFPs. However,
> there are several effects that limit the accuracy that you can get on longer
> links:
>
> * Dispersion of the fiber (as the lasers change temperature, their
> wavelength changes, and they experience a slightly different index of
> refraction, hence propagation speed.
>
> * Change in index of refraction in the fiber itself. The propagation speed
> of both the uplink and downlink wavelength change, in absolute sense but
> also their ratio changes. This is something the WR protocol can't
> detect/correct for.
>
> There are several people working on these issues, trying to improve both the
> calibration and stability even further.
>
> Regards, Paul Boven.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.