[time-nuts] Precise Time transfer and relative position over a short baseline

Magnus Danielson magnus at rubidium.dyndns.org
Mon Apr 11 06:27:57 UTC 2016


Hi,

I would look at White Rabbit and fibre.
Now, you say you can't use fibre. If you have line of sight you may use 
microwave (but not WLAN) or laser for a medium.

I would *really* consider pulling fiber after all. After that it is 
relatively cheap to achieve the rest.

Cheers,
Magnus

On 04/11/2016 07:00 AM, Bruce Griffiths wrote:
> There is a proposal to use multiple light bucket style optical telescopes to do Intensity stellar Interferometry over short baselines (up to perhaps 1km  or so) by using independent clocks to time tag photon  arrivals. store the time tags and process the data off line. Depending on the time tag resolution there is a need to measure the time differences between the independent clocks to an accuracy in the 1ns to 100ps range. Is there a better way of doing this other than using geodetic grade GPS receivers capable of GPS carrier phase measurements?Since the local clock flywheel oscillators will need to not deviate by more than 100ps or so over the several minutes required to perform the carrier phase averaging what sort of clock will be suitable apart from a good rubidium standard with a cleanup oscillator?
> NB Running fibres or coax between the telescopes isnt an option.
>
> The relative positions of the telescopes has to be known to within a cm or so for this to work.
> Bruce
>
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