[ntp:questions] Re: NMEA and PPS

DJ drnj at freemail.redherring.co.uk
Wed Jul 5 18:32:21 UTC 2006

Dufus - I meant stratum 1 !!!

Thanks for the info. NO need to build a PPS kernel then !


David Woolley wrote:
> In article <1152047875.382440.265180 at 75g2000cwc.googlegroups.com>,
> "DJ" <drnj at freemail.redherring.co.uk> wrote:
> > use of fudge time1 I can get my ntpd to act as a stratum 0 server and
> You mean stratum 1.  A value of 0 indicates unsynchronised.  The reference
> clock will be stratum zero, but the NTP protocol will report statum
> 1.
> > will track pool ntp servers to within 100ms drift . I wish to improve
> > the precision/accuracy and would like to use the PPS kernel/drivers. Is
> > this possible with a simple NMEA device i.e. does the PPS kernel patch
> > give a better stability or do I need a PPS gps clock ?
> You require a time transfer receiver.  Your problems are not fundamental
> to NMEA, but navigation receivers will generally not pay attention to
> accurate timing of the time messages and even time transfer receivers
> may assume that their PPS output is accurate, so the NMEA doesn't need
> to be.  I don't know if there are any time transfer receivers without
> PPS, although, if there are, they would, presumably have low jitter
> NMEA outputs.
> The ntpd PPS code is of no benefit unless the receiver generates an
> accurate PPS signal.

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