[ntp:questions] NTP absolute accuracy?

RedGrittyBrick RedGrittyBrick at spamweary.invalid
Mon Nov 2 10:42:54 UTC 2009


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

At *source*, the distance to the transmitter must surely be a lot less 
than 3 km :-)

According to the National Physics Laboratory "Every UTC second is marked 
by an 'off' preceded by at least 500 ms of carrier, and this second 
marker is transmitted with an accuracy better than ±1 ms." from which I 
conclude it's never going to to be more accurate than a few ms at 
*receiver*.

Someone has compared a KHz radio time signal from DCF with the GHz radio 
time signals from GPS: http://www.hopf-time.com/en/dcf-gps.htm. I 
imagine MSF accuracy is similar to DCF.

-- 
RGB




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