[Pool] Question about precision I can expect

[Shoppa, Tim]

There can be a delay in the serial port link to the radio clock, or in latencies in the host operating system, or other places. These have to be adjusted for in your ntp.conf with the offset specified as a "time1" option.

There can also be asymmetric delays in network connections that cause systemic offsets to occur. These asymmetric delays could theoretically be anywhere between you and the monitoring station, but unless you live in some really remote part of the world they are probably close to you.
________________________________________
From: pool-bounces+tshoppa=wmata.com at lists.ntp.org [pool-bounces+tshoppa=wmata.com at lists.ntp.org] on behalf of ntp at jama.is [ntp at jama.is]
Sent: Wednesday, August 01, 2012 4:59 AM
To: pool at lists.ntp.org
Subject: [Pool] Question about precision I can expect

Hi,

after reading the "The NTP Pool needs more servers" call for joining the
ntp.org pool I setup the ntp server ntp.jama.is. It uses a radio clock,
which gets the time from the german radio DCF77. The monitoring page at
pool.ntp.org showed a offset of about -25ms which recently increased to
-32ms. You can see a screen shot here:
http://s8.postimage.org/69taj7mwl/ntp_graph.png

I am wondering why this happened. What precision can I expect from a ntp
stratum 1 server? If I compare with other stratum 1 servers their time is
around +-5 ms. Any ideas?

Thanks



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