Unruh schrieb: > "Richard B. Gilbert" <[EMAIL PROTECTED]> writes: > >> David Woolley wrote: >>> Richard B. Gilbert wrote: >>> >>>> To turn your equipment on after months of downtime and expect it to >>>> lock on to the correct time with millisecond accuracy within seconds >>>> is asking for a hell of a lot. >>> Not really. He's starting a GPS receiver at the same time and that has >>> to lock to 50ns. >>> >>> Doing it on a general purpose computer is more difficult, but not >>> particularly impossible. > >> Even with GPS and a full four satellite fix, ten seconds to synchronize >> is extremely ambitious!! You can set the time to within whatever >> precision the hardware and software support but that is only half the >> problem. You also need to set the correct clock frequency. On a cold >> start, the clock frequency is a moving target as the hardware warms up. > > With a minpoll of 4, just setting the phase correctly with zero drift > compensation would at worst be out by 1ms by the next reading. And you can > get a pretty good estimate of the drift, even if it is changing. The temp > coefficient is not 10PPM/degree C. More like 1 or less. That means the > first few measurements gives a pretty good estimate of the drift ( ie to a > few PPM) and then the finer corrections can come while things settle down. > > > > >> I would expect to wait at least thirty minutes for the system to >> stabilize with both the correct phase (time) and frequency.
So i could do some more tests: I could not reproduce the strange running off for 200 ms and more once it was gone! The thread-starter had right the same issue and gave up on ntp after all.. Any ideas on this, anyone? So now things look somewhat better, if I boot the machine without a driftfile, (300 and something in there! ...) it runs away for a little while, but not very far, some ten ms i recall. If let run then and given the chance to write that driftfile, I can reboot and it sets time with an offset of around 20-30 ms and from there on slowly tears it to zero. So the good news is, the heavy drifting is in control! What looks unneccesary is the initial offset.. Btw, I have minpoll 4 maxpoll 4 in my ntp.conf and ntpq -p says: "poll 16". Is it the poll of ntpq -p or of ntpd? Best regards, ../nico _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
