[ntp:questions] Reasons of NTP not to use GPS source

Igor Pavlov pavlov.ig at gmail.com
Mon Sep 16 10:52:15 UTC 2013


Actualy I didn't know about mission of "flag2", "time2" and other
parameters like these. Now I'll try to do what Elliot says.

Mark, I don't have etc/issue file
My ntpd.conf :

driftfile "C:\Tools\NTP\etc\ntp.drift"
server 127.127.20.2 minpoll 4 mode 80 prefer # NIIDAR GPS receiver (Geos 1m
based)
fudge 127.127.20.3 flag2 1 refid GPS

server 0.ru.pool.ntp.org iburst
server 1.ru.pool.ntp.org iburst
server 2.ru.pool.ntp.org iburst





2013/9/16 Mark C. Stephens <marks at non-stop.com.au>

> Igor, please post the contents of
> 1. /etc/ntp.conf
> 2. /etc/issue
>
>
>
> -----Original Message-----
> From: questions-bounces+marks=non-stop.com.au at lists.ntp.org [mailto:
> questions-bounces+marks=non-stop.com.au at lists.ntp.org] On Behalf Of Igor
> Pavlov
> Sent: Monday, 16 September 2013 5:56 PM
> To: Rob
> Cc: questions
> Subject: Re: [ntp:questions] Reasons of NTP not to use GPS source
>
> Sorry, didn't see the first part of your answer.
> I thought that offset - it's offset of current system time from NMEA-based
> info.
> But if system time would be set to this NMEA-based time, than offset would
> not be so great. Isn't it?
> But NTP prefer to sync to other sources - Why?
>
>
> 2013/9/16 Igor Pavlov <pavlov.ig at gmail.com>
>
> > I already tryed to use PPS from my GPS receiver connected to DCD-pin
> > of the same RS-232.
> > But I had PPS also marked as "x", that is why I tryed first to fix
> > problems with NMEA-based GPS data separate from PPS.
> > I will try to connect PPS again.
> >
> > But I can't understand why it is marked "x"? What is wrong with it?
> >
> >
> > 2013/9/16 Rob <nomail at example.com>
> >
> >> Igor Pavlov <pavlov.ig at gmail.com> wrote:
> >> > Hi!
> >> >
> >> > I am using GPS-receiver based on Geos-1m chip (
> >> > http://www.geostar-navigation.com/en/navigation_05.html)
> >> >
> >> > I connected it to serial port and configured NTP.
> >> > It becomes unused by NTP: when do ntpq -p reuest ti puts "x" near
> >> > "GPS_NMEA(1)" record.
> >> >
> >> > What reasons can be for this?
> >>
> >> A GPS with NMEA protocol is usually a very lousy time source.
> >> You can see this in your output: the time offset relative to the
> >> internet sources is very large:
> >>
> >> >      remote           refid      st t when poll reach   delay   offset
> >> >  jitter
> >> >
> >> =====================================================================
> >> =========
> >> > xGPS_NMEA(1)     .GPS.            0 l   14   16  377    0.000  -303.07
> >> > 4.292
> >> > *stratum1.net    .PPS.            1 u   62   64  377   62.800
>  -68.052
> >> >  43.693
> >> > +dl120g7.naviteh 194.190.168.1    2 u   58   64  377   30.151  -100.04
> >> >  52.432
> >> > +89.221.207.113  192.36.133.25    2 u    -   64  377   10.006  -105.88
> >> >  64.279
> >>
> >> That is why ntpd declares the time as invalid and attempts to use the
> >> 3 other sources instead.
> >>
> >> When you want to fix this, you should use PPS with the receiver, when
> >> possible.
> >>
> >> _______________________________________________
> >> questions mailing list
> >> questions at lists.ntp.org
> >> http://lists.ntp.org/listinfo/questions
> >>
> >
> >
> >
> > --
> > Игорь Павлов
> >
>
>
>
> --
> Игорь Павлов
> _______________________________________________
> questions mailing list
> questions at lists.ntp.org
> http://lists.ntp.org/listinfo/questions
>
>


-- 
Игорь Павлов


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