[ntp:questions] Is this normal?

David Woolley david at ex.djwhome.demon.invalid
Tue May 11 21:08:04 UTC 2010

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.

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