[ntp:questions] NTP absolute accuracy?

Unruh unruh-spam at physics.ubc.ca
Sun Nov 1 23:52:17 UTC 2009


"David J Taylor" <david-taylor at blueyonder.not-this-bit.nor-this.co.uk.invalid> writes:

>"Unruh" <> wrote in message news:vCjHm.50153$Db2.9407 at edtnps83...
>[]
>>>UK 60KHz radio time signal.
>>
>> Ah, OK. Its accuracy is probably not much better than a few msec I 
>> assume.
>> GPS is a few usec. Since the network gives accuracies of better than a 
>> few ms, MSF
>> is not a good way of testing the accuracy of network set clocks.

>At source, it's recently been within about 10 microseconds:

Sorry, at 10usec, the distance away of the transmitter must be less than 3 km.
Also your system needs to see the start of the tone to 10usec which means that the
tone would have to be about 1MHz which is a bit beyond audio.



>  http://www.npl.co.uk/science-technology/time-frequency/time/products-and-services/msf-bulletins

>  http://resource.npl.co.uk/time/bulletins/msf/msfbul_08_2009.pdf

>In the field, the accuracy will depend on the receiver you use, the 
>propagation, and the quality of signal you have.  A few milliseconds is 
>probably a fair estimate, although it would be interesting to see some 
>measured values.

>Cheers,
>David 




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