Joshua Coombs wrote:
I finally have my stratum 2 servers working as good as I think they can
given their environments. Now I'm working on my stratum 1 clock which
pulls it's time via ACTS.
I'm currently dialing NIST so I can take advantage of the automatic
latency compensation. Problem is, the time I get back seems to vary by
up to 20ms. I may get 3 or 4 calls where the reported time stays within
a couple ms of what I believe true time to be, and then a call will come
back close to 20ms off. When ntpd has decided to stretch out to it's
max call interval, that glitch induces drift in the clock, resulting in
an eventual 40ms offset before it corrects.
I've tried the following:
- switched to manual latency adjustment using time1
- only configured 1 number to avoid different latencies for different paths
- dialing USNO instead of NIST
I can't seem to shake the random wild offsets.
I'm running the 4.2.1RC on FreeBSD 4.11, soekris 4501, and a Microcom
28.8 external modem.
I'm open to any suggestions on how to improve things.
Joshua Coombs
I've seen ACTS referred to as "Automated Containerized Trash Service".
What you see may be the best that ACTS can do.
Have you considered using another technology? A GPS receiver is not
terribly expensive (as low as $85 US) and such a receiver designed for
timing applications can deliver accuracy in the neighborhood of 1
microsecond. The PPS signal is accurate to better than 100 nanoseconds
but few computers are capable of that degree of accuracy. 1 microsecond
is easily obtainable. I use a Sun Ultra 10 (440MHz processor),
Solaris 8 and ntpd 4.0 and get that accuracy. That's eight year old
technology; more modern hardware and software might do better.
_______________________________________________
questions mailing list
[email protected]
https://lists.ntp.isc.org/mailman/listinfo/questions
