[ntp:questions] timing issue with a HP 58534A

David Lord snews at lordynet.org
Mon Feb 6 20:04:05 UTC 2012


Mark C. Stephens wrote:
> That clarifies things a lot, Mr. Hart.
> 
> Both of the ntp servers have an * not an o. and I'd really like to squeeze some more accuracy out of it ;)
> 
> [root at NTP ~]# ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *GPS_NMEA(0)     .GPS.            0 l   11   16  377    0.000   -0.238   0.039
> -admin.non-stop. .GPS.            1 u   35   64  376    0.272   11.374   0.380
>  . 
>  .
>  .
> 
> Concentrating on the freebsd box:
> 
>  7 Feb 00:22:51 ntpd[5091]: ntpd exiting on signal 15
>  7 Feb 00:22:52 ntpd[5117]: proto: precision = 2.236 usec
>  7 Feb 00:22:52 ntpd[5117]: ntp_io: estimated max descriptors: 11095, initial socket boundary: 20
>  7 Feb 00:22:52 ntpd[5117]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
>  7 Feb 00:22:52 ntpd[5117]: Listen and drop on 1 v6wildcard :: UDP 123
>  7 Feb 00:22:52 ntpd[5117]: Listen normally on 2 em0 192.168.5.112 UDP 123
>  7 Feb 00:22:52 ntpd[5117]: Listen normally on 3 lo0 fe80::1 UDP 123
>  7 Feb 00:22:52 ntpd[5117]: Listen normally on 4 lo0 ::1 UDP 123
>  7 Feb 00:22:52 ntpd[5117]: Listen normally on 5 lo0 127.0.0.1 UDP 123
>  7 Feb 00:22:52 ntpd[5117]: peers refreshed
>  7 Feb 00:22:52 ntpd[5117]: Listening on routing socket on fd #26 for interface updates
>  7 Feb 00:22:52 ntpd[5117]: GPS_NMEA(0) serial /dev/gps0 open at 9600 bps
>  7 Feb 00:22:52 ntpd[5117]: GPS_NMEA(0) 8011 81 mobilize assoc 60778
>  7 Feb 00:22:52 ntpd[5117]: 192.168.5.8 8011 81 mobilize assoc 60779
>  7 Feb 00:22:52 ntpd[5117]: 0.0.0.0 c016 06 restart
>  7 Feb 00:22:52 ntpd[5117]: 0.0.0.0 c012 02 freq_set kernel 119.785 PPM
>  7 Feb 00:22:53 ntpd[5117]: GPS_NMEA(0) 8024 84 reachable
>  7 Feb 00:22:53 ntpd[5117]: GPS_NMEA(0) 903a 8a sys_peer
>  7 Feb 00:22:53 ntpd[5117]: 0.0.0.0 c415 05 clock_sync
>  7 Feb 00:23:19 ntpd[5117]: 192.168.5.8 8024 84 reachable
>  7 Feb 00:24:13 ntpd[5117]: GPS_NMEA(0) 931a 8a sys_peer
> 
> I can't see any sign of a whinge?
> 
> [root at NTP /etc/rc.d]# ntpdc -c kerninfo
> pll offset:           -0.00020659 s
> pll frequency:        107.709 ppm
> maximum error:        0.007036 s
> estimated error:      3.9e-05 s
> status:               2001  pll nano
> pll time constant:    4
> precision:            1e-09 s
> frequency tolerance:  496 ppm
> pps frequency:        119.785 ppm
> pps stability:        0.000 ppm
> pps jitter:           0 s
> calibration interval: 4 s
> calibration cycles:   0
> jitter exceeded:      0
> stability exceeded:   0
> calibration errors:   0
> 
> Also can't see any PPS there either.
> 
> It's definitely running the PPS kernel I built: 
> [root at NTP /etc/rc.d]# uname -a
> FreeBSD NTP 8.2-RELEASE-p6 FreeBSD 8.2-RELEASE-p6 #1: Sun Feb  5 10:39:17 EST 2012     root at NTP:/usr/obj/usr/src/sys/PPS  i386
> 
> [root at NTP /etc]# cat /etc/make.conf
> KERNCONF= PPS GENERIC
> # added by use.perl 2012-01-25 15:59:06
> PERL_VERSION=5.10.1
> 
> [root at NTP /usr/src/sys/i386/conf]# cat PPS
> #
> # PPS -- Generic kernel configuration file for FreeBSD/i386 PPS
> #
> include GENERIC
> ident PPS-GENERIC
> options PPS_SYNC
> 
> and then 
> make buildkernel KERNCONF=PPS
> make installkernel KERNCONF=PPS
> 
> I'll go back and do the last 2 steps and reboot and see how it goes.
> Actually really beginning to like working with bsd.
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Looking at the windows box:
> 
> C:\Program Files\NTP\bin>ntpq -c peer
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *GPS_NMEA(1)     .GPS.            0 l   12   16  377    0.000    2.901   0.158
> +ntp             .GPS.            1 s   47   64  377    0.308  -11.099   0.240
>  .
>  .
>  .
> 
> C:\Program Files\NTP\bin>ntpq -c kern
> associd=0 status=0415 leap_none, sync_uhf_radio, 1 event, clock_sync,
> pll offset:            0
> pll frequency:         0
> maximum error:         0
> estimated error:       0
> pll time constant:     0
> precision:             0
> frequency tolerance:   0
> pps frequency:         0
> pps stability:         0
> pps jitter:            0
> calibration interval   0
> calibration cycles:    0
> jitter exceeded:       0
> stability exceeded:    0
> calibration errors:    0
> 
> Aha, in event viewer I see:
> Using user-mode PPS timestamp for GPS_NMEA(1)   
> 
> Could there be something amiss with my PPS pulse?
> 

Just in case you haven't already set these:

I use NetBSD but I've also had pps working with Ubuntu.

With NetBSD I have to setup symlinks for /dev/pps(n)
from the serial port.

ls -l /dev/
....
pps1 -> /dev/ttyU0
pps2 -> /dev/tty00

I also use in ntp.conf:
tos mindist 0.500

Otherwise sync to my Garmin 18x-LVC was not reliable. I'm now
using a Sure GP-GS010 but only change was to
fudge 127.127.20.2 time2 0.350 refid GPSb

previously time2 0.65

GPS firmware for the GPS combined with different versions
of ntpd  require their own settings.


David



More information about the questions mailing list