[ntp:questions] beginner needs help with gps nmea setup and pps

ramb at sonic.net ramb at sonic.net
Fri Feb 11 16:06:19 UTC 2005


I'm getting started with NTP and am having some trouble setting it up.

Is there a difference between these two pps things? I have a gps receiver
that has a pps output. I want to set up an NTP server that is talking to
the gps receiver and uses the pps output as well.

I think I've enabled the PPS output of my GPS receiver.

Is this enough for /etc/ntp.conf?

enable stats monitor pps
server 127.127.20.1
server 127.127.22.0
logconfig +clockall


This is how /dev is setup.

lrwxrwxrwx   1 root root         10 Feb  6 15:01 gps0 -> /dev/ttyS0
lrwxrwxrwx   1 root root         10 Feb 11 06:38 gps1 -> /dev/ttyS0
lrwxrwxrwx   1 root root         10 Feb 11 07:59 pps0 -> /dev/ttyS0

Something is still not right since I am seeing these kinds of messages
in my system log files:

Feb 11 07:59:35 scrub ntpd[5834]: kernel time sync status 0040
Feb 11 07:59:37 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_fault' (0x03)
Feb 11 07:59:37 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_okay' (0x00)
Feb 11 08:00:40 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_fault' (0x03)
Feb 11 08:00:40 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_okay' (0x00)
Feb 11 08:00:41 scrub ntpd[5834]: clock PPS(0) event 'clk_noreply' (0x01)
Feb 11 08:01:01 scrub crond(pam_unix)[5837]: session opened for user root by (uid=0)
Feb 11 08:01:02 scrub crond(pam_unix)[5837]: session closed for user root
Feb 11 08:01:45 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_fault' (0x03)
Feb 11 08:01:45 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_okay' (0x00)
Feb 11 08:02:51 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_fault' (0x03)
Feb 11 08:02:51 scrub ntpd[5834]: clock GPS_NMEA(1) event 'clk_okay' (0x00)


I'm running a Fedora Core 3 linux distribution - do I need to build a custom
kernel to get the PPS thing to work?

Thanks for any help.
-Ram



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