On Fri, Feb 13, 2015 at 8:48 PM, William Unruh <un...@invalid.ca> wrote:
> > > > I had a properly set up PPS source to do the comparison. > > As did I. > Ooops, I see that the text/plain part of the message was damaged. I was quoting you saying: " I had a properly set up PPS source" and my response was we have no way of knowing that but you've clarified that. However I believe the minpoll 4 advice predates minpoll 3. Although much better than the ntp.org docs (xntp ... really!) the udel documents are not completely consistent. In any case all of my comments are specific to a PPS refclock, which you mentioned in the post that prompted my reponse, and nanosecond jitter. That value is significant only in so far was we can ignore jitter and focus on wander. Poll 4 for PPS, Poll 6-10 for network. There's an assumption that the Allan intercept for "fast" local networks is 512s and that the time constant jitter versus wander trade-off supports using minpoll 4 but I think the correct choice is three (minpoll 3 maxpoll 3) and my results reflect that. > Note that since the effective poll interval is 3 higher > than the nominal poll interval, > and since the convergence time scale is > larger than one poll interval, this would give a convergence time of > greater than 2^9 sec, or 500 sec (10 min) I'm not completely clear on what you mean here but in any case using a time constant of 256s would be expected to cut any time in half. It also worth noting that the bulk of offset "error" is corrected very quickly with only the residue taking a significant amount of time. However you've not responded to my question regarding your deep concerns. For years you've complained about the ntpd pll and on occasion suggested chrony. Now a replacement is being developed. So why do you continue to focus on what you consider to be defects in ntpd? _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
