[ntp:questions] How to debug GPS PPS?

Thomas Laus lausts at acm.org
Wed Feb 17 18:20:36 UTC 2010


On 2010-02-17, xyz-2041 <xyz2041 at gmail.com> wrote:
>
> OK.  Did yesterday:
> http://www.a7h.com/~stuph/var--log--ntp--clockstats-2010-Feb-16.txt
>
> This is today's output:
> http://www.a7h.com/~stuph/var--log--ntp--clockstats-2010-Feb-17--1025.txt
>
>
I looked over your log and it looks a lot like mine except for the
complaints about your serial port.  This is mine:

FreeBSD 7.3-PRERELEASE (MAIL) #2: Sat Feb 13 12:33:25 EST 2010

This is the contents of my /etc/devfs.conf:

SSH Secure Shell 3.2.9 (Build 283)
Copyright (c) 2000-2003 SSH Communications Security Corp -
http://www.ssh.com/

This copy of SSH Secure Shell is a non-commercial version.
This version does not include PKI and PKCS #11 functionality.


Last login: Wed Feb 17 2010 12:31:50 -0500 from laust2
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights
reserved.

FreeBSD 7.3-PRERELEASE (MAIL) #2: Sat Feb 13 12:33:25 EST 2010

Welcome to FreeBSD!


These are the Oncore related entries in my syslog:

iFeb 13 18:29:48 mail ntpd[536]: ntpd 4.2.7p5 at 1.2122-o Mon Jan  4 14:52:18 UTC 2010 (1)
Feb 13 18:29:48 mail ntpd[537]: proto: precision = 1.117 usec
Feb 13 18:29:50 mail ntpd[537]: ONCORE[0]: ONCORE DRIVER -- CONFIGURING
Feb 13 18:29:50 mail ntpd[537]: ONCORE[0]: state = ONCORE_NO_IDEA
Feb 13 18:29:50 mail ntpd[537]: ONCORE[0]: ONCORE: Can't open SHMEM file
Feb 13 18:29:50 mail ntpd[537]: ONCORE[0]: ONCORE: Can't open shmem
Feb 13 18:29:50 mail ntpd[537]: ONCORE[0]: state = ONCORE_CHECK_ID
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: @@Cj
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: COPYRIGHT 1991-1996 MOTOROLAINC.
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: SFTW P/N # 98-P36830P
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: SOFTWARE VER # 8
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: SOFTWARE REV # 8
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: SOFTWARE DATE  06 Aug 1996
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: MODEL #    B4121Z1115
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: HDWR P/N # _
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: SERIAL #   SSG0228726
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: MANUFACTUR DATE 7E22
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: OPTIONS LIST    IBC
Feb 13 18:29:51 mail ntpd[537]: ONCORE[0]: state = ONCORE_CHECK_CHAN
Feb 13 18:29:54 mail ntpd[537]: ONCORE[0]: state = ONCORE_HAVE_CHAN
Feb 13 18:29:55 mail ntpd[537]: ONCORE[0]: Oncore: Resend @@Cj
Feb 13 18:29:55 mail ntpd[537]: ONCORE[0]: state = ONCORE_TEST_SENT
Feb 13 18:30:03 mail ntpd[537]: ONCORE[0]: GPS antenna: OK
Feb 13 18:30:03 mail ntpd[537]: ONCORE[0]: state = ONCORE_INIT
Feb 13 18:30:11 mail ntpd[537]: ONCORE[0]: Oncore: Resend @@Cj
Feb 13 18:30:11 mail ntpd[537]: ONCORE[0]: state = ONCORE_ALMANAC
Feb 13 18:30:13 mail ntpd[537]: ONCORE[0]: Bd: Almanac LOADED, week =35, t = 36, 30 SVs: fefffffe
Feb 13 18:30:16 mail ntpd[537]: ONCORE[0]: Have now loaded an ALMANAC
Feb 13 18:30:16 mail ntpd[537]: ONCORE[0]: state = ONCORE_RUN
Feb 13 18:30:16 mail ntpd[537]: ONCORE[0]: SSstate = ONCORE_SS_DONE
Feb 13 18:30:16 mail ntpd[537]: ONCORE[0]: ONCORE: Detected TRAIM, TRAIM= ON
Feb 13 18:38:53 mail ntpd[537]: ONCORE[0]: Set peer.leap toLEAP_NOWARNING
Feb 13 19:08:53 mail ntpd[537]: ONCORE[0]: Set peer.leap toLEAP_NOWARNING
Feb 13 20:04:11 mail ntpd[537]: ONCORE[0]: Bd: Almanac LOADED, week =35, t = 57, 30 SVs: fefffffe

> I wonder why that is.  Is there some kind of tool to look at
> the raw output in FreeBSD command line mode?   No X-windows
> on this box.
>
The entries in your log indicate that you are communicating with your
Oncore receiver.  It sees the firmware information very well.  The
message:

55242 74297.142 127.127.30.0 ONCORE[0]: ONCORE: oncore_get_timestamp,error serial pps

Seems to be indicating a problem in your serial interface.  Are you
using an interface board to connect your Oncore TTL signals to RS-232?
I use one of the TAPR boards for that purpose.  Your tester shows data
being sent on all appropriate pins because all LED's are blinking.
Right now, I am stumped!  Someone with more knowledge is welcome to
chime into this discussion.
>
>>Precision of -20 is what I see on my setup.
>
> What does this mean exactly?
>
>From the NTP Project documentation page:

In NTP precision is determined automatically, and it is measured as a 
power of two. For example when ntpq -c rl prints precision=-16, the
precision is about 15 microseconds (2^-16 s).

It looks like yours and my NTP clocks are good to 2^-20s.

Tom

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