[ntp:questions] Is this normal?

unruh unruh at wormhole.physics.ubc.ca
Tue May 11 21:24:02 UTC 2010

On 2010-05-11, David Woolley <david at ex.djwhome.demon.invalid> wrote:
> Russell, David wrote:
>> I am trying to verify the correct implementation of NTP on a device
>> that is configured to poll a GPS based dedicated time server on the
>> local area network. The round trip times to this stratum 1 vary between
>> 3.3 and 3.4ms.
>> I have plotted the offset vs drift in the included jpg.  The drift
>> rate varies between -3 and -3.2 us/s and the offset is +/- 200us.
>> Note that the first part of the graph is when NTP started.
> It is not permissible to post JPGs to non-binaries Usenet groups (I 
> guess you used the email gateway - the binary was stripped.)  Also, 
> given the likely content of the image (i.e. line art) JPG is a very poor 
> choice of image format.
> You haven't told us how well controlled the temperature of the crystal 
> is.  200  ppb sounds good unless the crystal is ovened or the machine is 
> in an air conditioned room and has constant power demand.

That was plus or minus 3PPM he was claiming

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