Dear Gary,
sorry if the email is a bit off topic.
Finally I'm on the finishing line for my time measurement system.
Last Sunday I made the first race and noticed a problem that I believe I had not had before.
The problem lies in the adjustment of time.
I have to tell you that I turn on the system a few hours before the race to give time to level the time.
Everything runs on raspberry PI 3 model A + and I also added an external RTC (DS3231).
Logically gpsd works properly and with the PPS signal that is always present all the time.
Last night I wanted to check the problem and left the system on all night. This morning I still noticed the uncertainty of the time that went from an offset of 0.002 to 999.99 on ntpmon and on gpsd a PPS from 0,0000453 to -0.9999.
Honestly, I don't know where I'm wrong.
Below is my ntpd.conf file
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1 mask 255.255.255.0
restrict -6 ::1
# GPS PPS reference (NTP1)
server 127.127.28.1 minpoll 4 maxpoll 4 prefer true
fudge 127.127.28.1 refid PPS
fudge 127.127.28.1 flag1 1
# GPS Serial data reference (NTP0)
server 127.127.28.0 minpoll 4 maxpoll 4
fudge 127.127.28.0 time1 0.9999 refid GPS
#Log
driftfile /var/lib/ntp/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
logfile /var/log/ntpd.log
logconfig =syncall +clockall +peerall +sysall