[LEAPSECS] preprint about timekeeping for neutrino experiment

[François Meyer]

On Fri, 30 Sep 2011, bg at lysator.liu.se wrote:


> Hi François

>

>> And the clocks are not locked to a receiver, they are free but the offset

>> is continuously monitored through those CV measurement.

>

> Would you not lock the GPS (GNSS) receivers to the CS-clocks being compared?


Timing receivers may use an external frequency reference
to drive internal electronics. This is the only lock and
it is completely independent of GPS measurements: as time 
transfer is concerned, GPS Time is not a reference, it 
is a measurement artifact that cancels out when you process
data involved when comparing two remote clocks. So what you
need most is to make sure that the acquisition and processing schemes
are as simple and as identical as possible on both sites and to
avoid adding differential errors while trying to get a better-looking
realisation of GPS Time locally. You could benefit the latter if 
your clock was stand alone, but you would degrade the results of a
remote comparison by ruining the assumptions underlying Common View 
time transfers.

-- 
Francois Meyer    Tel : (+33) 3 81 66 69 27   Fax : 3 81 66 69 44
Observatoire de Besancon - BP1615 - 25010 Besancon cedex - FRANCE
Institut UTINAM * Universite de Franche-Comte * CNRS UMR 6213 ***