[ntp:questions] Offset Average (Normal)?

David Lord snews at lordynet.org
Tue Mar 13 13:59:58 UTC 2012


Alby VA wrote:
> On Mar 13, 8:27 am, David Lord <sn... at lordynet.org> wrote:

.....

>> I've not noticed any significant difference after swapping to
>> use only NMEA driver as from March  2, 2012.
>>
>> Also version of ntpd I was using in 2008/2009 didn't have nmea
>> driver with support for PPS.
>>
>> NetBSD-5
>> Garmin 18X-LVC used from 2009 to March 2011.
>> Sure GPS used from March 2011 to date.
>> Serial cable length was extended by about 17m to confirm that
>> working over that distance would not be a problem.
>>
>> Atom driver used from 2009
>> /etc/ntp.conf.11122702
>> #############
>> server  127.127.20.2  mode 18  prefer
>> fudge   127.127.20.2  time2 0.350  refid GPSb
>> server  127.127.22.2
>> fudge   127.127.22.2  flag2 0  flag3 1  refid GPSb
>> #############
>>
>> peerstats.20120108
>>         ident     cnt     mean     rms      max     delay     dist     disp
>> ==========================================================================
>> 127.127.20.2    1350  -63.925   14.862   50.035    0.000    2.408    1.722
>> 127.127.22.2    1350    0.000    0.003    0.030    0.000    0.928    0.928
>>
>> loopstats.20120108
>> loop 1350, 7+/-24.0, rms 3.4, freq -35.89+/-0.159, var 0.078
>>
>> /etc/ntp.conf.12030801
>> #############
>> server  127.127.20.2  mode 18
>> fudge   127.127.20.2  time2 0.410  flag1 1  flag2 0  flag3 1  refid GPSb
>> #############
>>
>> peerstats.20120312
>>         ident     cnt     mean     rms      max     delay     dist     disp
>> ==========================================================================
>> 127.127.20.2    1350    0.000    0.003    0.028    0.000    0.928    0.928
>>
>> loopstats.20120312
>> loop 1350, 3+/-25.1, rms 3.3, freq -35.13+/-0.204, var 0.054
>>
>> David
> 
> 
> 
> I'll say there has been an improvement, but does this look weird?
> What is (oGPS_NMEA) telling me?
> 
> NOTES: (Yes I know, I need to increase the minpoll on remote servers.)
> ------------
>      remote           refid      st t when poll reach   delay
> offset  jitter
> ==============================================================================
>  utcnist2.colora .ACTS.           1 u   57   64   11   56.500
> 2.475   2.852
> +ntp.alaska.edu  .GPS.            1 u    1   64  357  113.075
> -0.537   1.467
> -tick.usask.ca   .GPS.            1 u   40   64  377   95.721
> -8.491   0.737
> +cronos.cenam.mx .GPS.            1 u    5   64  377   88.488
> -2.094   1.823
> *ntp1.usno.navy. .USNO.           1 u   47   64  377   20.605
> 2.849   4.014
> -time-a.nist.gov .ACTS.           1 u    2   64  203   84.047
> 38.336  38.109
> oGPS_NMEA(0)     .PPS.            0 l    7   16  377    0.000
> 0.002   0.002
> 

That seems to be working ok.

The NMEA sentences aren't being reported because PPS is being
used to condition the system clock.


David


> 
> 
> 
> Peerstats Before/After: [day, second, address, status, offset, delay,
> dispersion, skew (variance)]
> ---
> Before: 55999 1.493 127.127.20.0 914b -0.015715484 0.000000000
> 0.002563345 0.023433975
> After: 55999 48104.873 127.127.20.0 975a 0.000001154 0.000000000
> 0.000233462 0.000001907
> 
> 
> Offset Before: -0.015715484
> Offset After: 0.000001154
> 
> 
> 
> This is my current /etc/ntp.conf file (parsed):
> --
> #
> server 127.127.20.0 mode 18 minpoll 4 maxpoll 4  prefer
> fudge  127.127.20.0 flag1 1 flag3 1 refid PPS
> #
> 
> 
> 
> 
> 



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