[ntp:questions] Isolated Network Drift Problem

Calvin Webster cwebster at ec.rr.com
Wed Nov 26 13:18:43 UTC 2008


On Wed, 2008-11-26 at 00:43 +0000, Unruh wrote:
> >> After a bit of googling I found an excellent write-up on how to use
> one
> >> of these for an NTP server [http://time.qnan.org/ "Using a Garmin
> GPS 18
> >> LVC as NTP stratum-0 on Linux 2.6"]
> >> 
> 
> With your 100m setup you really want a buffer amp on the line. At
> 100m, the
> one way trip is .3ms, with reflections every .6ms which might make the
> system a bit weird. To get rid of the reflections you need a 100ohm
> termination if you use cat5e cable to lengthen the 5m wire on the
> receiver.

Thank you. Excellent idea. When we get it and find how long a cable we
really need we'll refine the calculations. :-)

./Cal




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