[ntp:questions] Accuracy of NTP - Advice Needed

Danny Mayer mayer at ntp.org
Wed Dec 28 12:46:47 UTC 2011


On 12/27/2011 11:45 PM, Greg Hennessy wrote:
> On 2011-12-28, Danny Mayer <mayer at ntp.org> wrote:
>> On 12/27/2011 9:08 PM, John Hasler wrote:
>>> Danny writes:
>>>> GPS is not used for this kind of thing, they are too inaccurate, so it
>>>> doesn't matter. They use atomic clocks.
>>>
>>> The requirement is for synchronization.  They use common view GPS.
>>
>> That's not good enough for experiments like this.
> 
> In what way is it not good enough? The neutrinos are apparently
> arriving about 60 nanoseconds early, the distance is known, through
> GPS to 10's of centimeters, and the time is synchronized, again
> through GPS (although a second method is used as a double check) to
> about 1 nanosecond. In what fashion is it 'not good enough'?

No, they use synchronized Cesium atomic clocks for time accuracy. GPS is
only used to get a fix on the location and I'm not sure that 10's of
centimeters is good enough for what they are trying to prove. I'd have
to look closely at the methods used and the data to even have a clue as
to what is needed and I have touched that stuff in years.

Danny


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