I am using the nmea driver to determine the rough time (seconds). I want to only use the WAN servers incase the GPS/PPS sources fail. Having the WAN servers with high offsets in the mix is causing me problems with precision.
Regards, Ed > -----Original Message----- > From: questions- > [email protected] > [mailto:questions- > [email protected]] On > Behalf Of Brian Utterback > Sent: Tuesday, January 15, 2013 2:38 PM > To: Edward T. Mischanko > Cc: [email protected] > Subject: Re: [ntp:questions] PPS only configuration > > You can't. The PPS feature can only use offsets up to .5 > seconds. If the > offset is greater than .5 the PPS will synchronize your system > to the > wrong second. In essence the PPS just locks the clock to the > nearest > second. So NTP PPS is designed to require another source of time > and > then on let the PPS kick in when the offset is below .5 seconds. > If you > circumvent that requirement, you run the rather high risk of > being some > integer multiple of seconds offset from the real time. > > > On 01/15/13 13:48, Edward T. Mischanko wrote: > > How do I configure NTPD so that only the PPS offset is used to > figure > > the clock offset, instead of factoring in the surviving back- > up > > servers that have bigger offsets? I only want the back-up > servers to > > come into play when, or if, the PPS fails. > > > > # > > enable pps > > enable kernel > > enable ntp > > tos minclock 4 > > tos minsane 3 > > tinker huffpuff 7200 > > # > > driftfile "/var/db/ntpd.drift" > > leapfile "/usr/home/ed/leap-seconds" > > # > > enable stats > > statistics loopstats > > statsdir "/usr/home/ed" > > filegen loopstats file loop type day > > # > > server 127.127.20.0 mode 18 minpoll 3 prefer > > fudge 127.127.20.0 time2 0.374000 > > server 127.127.22.0 minpoll 3 > > fudge 127.127.22.0 flag2 0 flag3 1 > > server 192.168.1.254 iburst minpoll 6 maxpoll 6 > > server tick.cerias.purdue.edu iburst minpoll 6 maxpoll 6 > > server tock.cerias.purdue.edu iburst minpoll 6 maxpoll 6 > > server tack.cerias.purdue.edu iburst minpoll 6 maxpoll 6 > > server nist1-chi.ustiming.org iburst minpoll 6 maxpoll 6 > > server nist.expertsmi.com iburst minpoll 6 maxpoll 6 > > server nist.netservicesgroup.com iburst minpoll 6 maxpoll 6 > > server ntp.your.org iburst minpoll 6 maxpoll 6 > > server navobs1.wustl.edu iburst minpoll 6 maxpoll 6 > > server utcnist2.colorado.edu iburst minpoll 6 maxpoll 6 > > server time-a.timefreq.bldrdoc.gov iburst minpoll 6 maxpoll 6 > > server ntp1.conectiv.com iburst minpoll 6 maxpoll 6 > > server east-pool.ustiming.org iburst minpoll 6 maxpoll 6 > > # > > _______________________________________________ > > questions mailing list > > [email protected] > > http://lists.ntp.org/listinfo/questions > > > -- > blu > > Always code as if the guy who ends up maintaining your code will > be a > violent psychopath who knows where you live. - Martin Golding > ---------------------------------------------------------------- > -------| > Brian Utterback - Solaris RPE, Oracle Corporation. > Ph:603-262-3916, Em:[email protected] > > _______________________________________________ > questions mailing list > [email protected] > http://lists.ntp.org/listinfo/questions _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
