[ntp:questions] PPS source not always being chosen?

John Ackermann N8UR jra at febo.com
Mon Aug 15 00:11:05 UTC 2005

I'm seeing a strange quirk in the selection process of my NTP servers
that use refclocks that provide both a serial data timestamp as well as
a PPS signal.  I mentioned this some time ago, and with the most recent
4.2.0a-20050720 snapshot (running on FreeBSD 5.4), I'm still seeing the
same thing.

Attached below are the results of ntpq -p showing that the PPS source,
while apparently far better in jitter and offset, is being deselected in
preference to the serial timestamp source.  That just doesn't seem
right.  Is there something in my configuration (sample attached below)
that might be causing this?

Any suggestions on how to solve this would be greatly appreciated.



jra at flob:~$ ssh tick ntpq -p
     remote           refid      st t when poll reach   delay   offset 
*GPS_HP(0)       .GPS.            0 l    4   64  377    0.000    2.582  
-PPS(0)          .PPSG.           0 l   16   64  377    0.000   -0.003  
-tock.febo.com   .GPS.            1 u   16   64  377    0.481    0.003  
+toe.febo.com    .PPSW.           1 u   17   64  377    0.460    3.111  
-time-A.timefreq .ACTS.           1 u   24   64  377   49.374    1.269  
+tock.usno.navy. .USNO.           1 u    6   64  377   51.010    3.595  
+ntp2.usno.navy. .USNO.           1 u   51   64  377   51.232    3.525  

# /etc/ntp.conf, configuration for ntpd

# ntpd will use syslog() if logfile is not defined
logfile /var/log/ntpd

driftfile /etc/ntp.drift
statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

enable pps

# Z3801A
server ttl 1 prefer
fudge time1 -0.963
fudge refid GPS

fudge refid PPSG
fudge flag3 1

#server tick.febo.com iburst
server tock.febo.com iburst
server toe.febo.com iburst
server time-c.timefreq.bldrdoc.gov iburst
server ntp1.usno.navy.mil iburst
server ntp2.usno.navy.mil iburst

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