[time-nuts] White Rabbit

[Paul Boven]

Hi Jim,

On 7/16/20 1:37 PM, Jim Palfreyman wrote:
> Anyone here have experience with White Rabbit products? Any thoughts would be appreciated.

Got to play with it extensively, using it to connect various radio 
telescopes together. There is a lively community around the White Rabbit 
project, and they have pushed it well beyond its original mission of 
controlling the LHC at CERN.

Due to its open source nature, all kinds of tinkering is possible. We 
use special low-jitter White Rabbit hardware for frequency distribution. 
Using SFPs with (stabilized) lasers, the range and stability can be 
greatly increased.

One of the things I've used it for is demonstrating VLBI fringes at 1.3 
GHz, over 135 km of fiber, with optical (bi-directional) amplification 
along the route. It's roughly one order of magnitude worse in ADEV than 
a H-maser, up to about 1,000 seconds, where the curves cross over.

https://pos.sissa.it/344/156/pdf

Timing accuracy can be kept well under 1ns, even on long haul links 
(e.g. 185 km) with semi-desert climate and overhead fibre. The timing 
stability is much better than that.

There are multiple vendors, and as the design is truly open, you could 
even build your own if you really wanted to. The project is still 
progressing, and work on a new generation of White Rabbit switches (with 
10Gb/s) and end-points is well under way.

Regards, Paul Boven.