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

Michael Wouters michaeljwouters at gmail.com
Mon Apr 11 04:35:41 EDT 2016


Dear Bruce

Posted too hastily ...

Since you don't care about absolute time, maybe using identical receivers
you might be able to get a few hundred ps synchronization using a PPP
solution,  for example.

Attached is 6 months of data for two Javad receivers, with daily PPP
solutions. The antennas for these receivers are separated by about 400 m.

Cheers
Michael

On Mon, Apr 11, 2016 at 3:00 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz
> 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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