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

Igor Pavlov pavlov.ig at gmail.com
Mon Sep 16 10:55:36 UTC 2013


Sorry, it's
fudge 127.127.20.2 flag2 1 refid GPS

The same as in "server" sentense. (I experimenting with PPS, with over
ports and so on, that's why it was mistake in message)

2013/9/16 Igor Pavlov <pavlov.ig at gmail.com>

> 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
>



-- 
Игорь Павлов


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