[ntp:questions] Re: Improving ACTS performance

David L. Mills mills at udel.edu
Tue Apr 11 02:27:38 UTC 2006


My experience with ACTS over a period of many months has been quite 
positive; however, at a poll interval of 36 hours you must expect normal 
room temperature variations to induce errors in the order of 10-50 ms. 
There is not much you can do about that other than to reduce the call 

At the moment I am using USNO for test. Expect errors in the 50 ms 
range, somewhat worse than NIST. It seems the primary reason for the 
increased jitter is the variation in call routing from call to call.


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

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