[time-nuts] Project on precise timing over Ethernet

Javier Serrano javier.serrano.pareja at gmail.com
Fri Sep 11 07:57:54 UTC 2009

Jim, I found a good reference for LOFAR clock and sync:
After a quick read, I think they would have been a perfect candidate to use
WR, pity it's a bit late. Their system uses quite a lot of cables to achieve
(worse than) what WR does with a single fiber, and there is no mention of
cabling delay compensation anywhere, which makes me think they must be doing
it by hand through some kind of calibration campaign at the beginning of the
run. We have done this in the past and it's both time-consuming and
error-prone, not to speak about thermal effects you just can't deal with in
this way. Anyway an interesting read. Thanks again for the idea.


On Thu, Sep 10, 2009 at 4:34 PM, Lux, Jim (337C)
<james.p.lux at jpl.nasa.gov>wrote:

> On 9/10/09 4:29 AM, "Javier Serrano" <javier.serrano.pareja at gmail.com>
> wrote:
> > Dear nuts,
> >
> > We have this ongoing project whose aim is to synchronize roughly one
> > thousand stations (typical distances around 10 km) to within 1 ns using
> > Ethernet:
> > http://www.ohwr.org/twiki/bin/view/OHR/WhiteRabbit/WhiteRabbit
> >
> Interesting stuff...
> Have you looked at what the giant phased array radio telescopes are doing?
> LOFAR and SKA both cover large areas, and have similar timing requirements.
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