[ntp:questions] Offset Average (Normal)?
David Lord
snews at lordynet.org
Tue Mar 13 12:27:56 UTC 2012
David J Taylor wrote:
>
> "Alby VA" <albyva at empire.org> wrote in message
> news:7824f31d-b72c-44eb-9eeb-b219a7543db3 at gr6g2000vbb.googlegroups.com...
> []
>> ntp2.usno.navy. .USNO. 1 u 11h 128 0 21.392
>> 11.022 0.000
>> -ntp0.usno.navy. .USNO. 1 u 512 128 370 25.747
>> -0.242 3.378
>> +ntp1.usno.navy. .USNO. 1 u 51 128 377 30.361
>> -1.445 2.473
>> -time-a.nist.gov .ACTS. 1 u 136 128 336 19.894
>> 0.582 5.715
>> +time-b.nist.gov .ACTS. 1 u 64 128 57 19.100
>> -0.948 2.129
>> oPPS(0) .PPS. 0 l 13 16 377 0.000
>> 0.502 0.153
>> *GPS_NMEA(0) .GPSb. 0 l 12 16 377 0.000
>> -38.705 13.177
>
> As Chris commented, you should maybe be using a single driver - here's
> mine for a GPS 18 LVC (which should be similar apart from the baud rate):
>
> ==============
> oGPS_NMEA(1) .PPS. 0 l 16 16 377 0.000 0.004
> 0.002
> +feenix .PPS. 1 u 29 32 377 0.267 -0.027
> 0.029
> +stamsund .PPS. 1 u 13 32 377 0.246 -0.028
> 0.035
> -time.hilo.net 130.88.212.143 3 u 67 1024 377 21.717 2.509
> 1.349
> -server0.terrybu 140.203.204.77 2 u 1023 1024 377 23.783 3.814
> 4.331
> +xinnaeus.bin.ed 129.215.64.32 2 u 677 1024 377 30.284 1.405
> 0.739
>
> and the configuration:
>
> driftfile /var/db/ntp.drift
> #
> server 127.127.20.1 mode 0 minpoll 4 maxpoll 4 prefer
> fudge 127.127.20.1 flag1 1 flag3 1 refid PPS
> #
> server 0.uk.pool.ntp.org iburst minpoll 10 maxpoll 10
> server 1.uk.pool.ntp.org iburst minpoll 10 maxpoll 10
> server 2.uk.pool.ntp.org iburst minpoll 10 maxpoll 10
> #
> leapfile /root/ntp/leap-seconds.3535142400
>
> (which has "just grown", so may not reflect current best practice).
>
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
More information about the questions
mailing list