[ntp:questions] Accuracy of NTP - Advice Needed
unruh
unruh at invalid.ca
Sat Dec 24 21:10:22 UTC 2011
On 2011-12-24, John Hasler <jhasler at newsguy.com> wrote:
> unruh writes:
>> They require ns accuracy in the timing and m accuracy in the
>> distance. And the timing is not simply gps ( although they could have
>> gotten that wrong) but then that timing has to be brought down into
>> the mine a km or so below ground and horizontally and that also has to
>> be surveyed for the distance.
>
> The NOvA detector is not in a mine so it should be possible to site the
> GPS receiver directly above it and drop a cable straight down. The same
> should be possible at the Fermi end. You could set up both timing
> chains at Fermilab (using indentical components including cable lengths
> if you want to be fanatical), calibrate them against each other for
> delay from antenna to output, and then pack one up and ship it up north
> (of course there may be good reasons not to do it this way). The
> surveying should be easier than in Europe: there's no mountain range in
> the way.
Surveying is done by GPS, as is timing so mountain ranges do not really
matter.
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