[ntp:questions] Can a clock drift be too big for ntpd?

Steve Kostecke kostecke at ntp.org
Sat Oct 20 15:06:39 UTC 2007


On 2007-10-20, Jos van de Ven <jos at notavailable.nl> wrote:

> My relative frequency is stable at about -148 ppm,

That number is the frequency CORRECTION applied by ntpd.

The fact this this value is stable is much more important than the value
itsself.

> so my system clock runs too fast due to 1000 Hz setting as I
> understand. I read that -148 ppm is not a good clock; should be no
> more than absolute 50 ppm.

That's simply not true. 

ntpd is able to apply a frequency correction of between -500 ppm and
+500 ppm.

As long as you are not operating at the margins (i.e. close to +/- 500)
ntpd will be able to discipline your clock.

-- 
Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/




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