Re: [ntp:questions] Seeking help configuring GPS refclock
> Why is your PPS at stratum 9? It should be stratum 0. I intentionally fudged the PPS refclock to stratum 9 so it wouldn't get picked. I wanted to force the server to pick the GPS_NMEA refclock. Actually, with PPS support enabled in the GPS_NMEA driver (flag1 = 1), I finally realized I don't need the separate PPS refclock anyway -- the GPS_NMEA driver deals with the PPS just fine all by itself -- so I took it out a couple of days ago. -- Rich Wales / ri...@richw.org / ri...@stanford.edu Wikipedia: http://en.wikipedia.org/wiki/User:Richwales Facebook: http://www.facebook.com/richwales ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Seeking help configuring GPS refclock
Rich Wales wrote: > Kevin Oberman wrote: > >> I don't know what the path is from your location to Stanford's NTP >> server . . . . > > I'm in a Stanford-built housing complex immediately adjacent to the > campus. The extra (and likely asymmetric) delay in my case is most > likely happening because my residence is connected via a cable modem > infrastructure run by the Stanford campus's IT services people. > >> NTP assumes the same delay for the return packet that it had for >> the request packet. If that is not the case, you will see a fixed >> offset. The only fix is a 'fudge' of the time for that server. If >> the path is unstable, even that will not work. > > I thought the "xleave" feature in ntp-dev was supposed to compensate > for asymmetric paths. All my systems are running ntp-dev and peering > with one another with "xleave" specified. You misunderstand the usage of the xleave option which is still experimental. It requires (currently) IEEE-1588 hardware to work and it needs to be set up to send additional time-delay information down the same path as the ntp packet. fudge is the right option if you know the amount of the asymmetry, which is hard to measure in the first place. For some reason I am having difficulty finding the fudge option in the html documentation but it should describe this. Danny -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Seeking help configuring GPS refclock
Rich Wales wrote: > My experimental stratum-1 server (using a Garmin GPS as its reference clock) > continues to run stably -- albeit with an offset several msec different from > the rest of my home LAN (which is synced to Stanford University's time server > infrastructure). > > remote refid st t when poll reach delay offset jitter > == > oGPS_NMEA(0) .GPS.0 l28 3770.000 -0.001 0.002 > PPS(0) .PPS.9 l68 3770.0000.000 0.002 > *iknow.richw.org 171.64.7.115 3 u 10 16 376 10.058 -9.249 3.871 > Why is your PPS at stratum 9? It should be stratum 0. You need to fix that. You didn't provide a copy of your ntp.conf file so it's hard to tell how you got that. Once you fix that it should synch to your refclock. Danny -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
