[time-nuts] Raspberry PI 3 NTP server with GPS time data.

Mike Cook michael.cook at sfr.fr
Mon Apr 25 04:18:43 EDT 2016


> Le 24 avr. 2016 à 20:51, jan hugo prins <jhp at jhprins.org> a écrit :
> 
> Hi,
> 
> To get a more stable NTP source into our production network I have
> started exprerimenting with a Raspberry PI 3 with a GPS head. GPS data
> is coming in fine, but the time is jumping around like a wild horse. The
> result is that the only thing I get out of this experiment so far is a
> more stable PPS signal in my NTP config but after some time both the GPS
> time and the PPS are marked a false ticker and the only thing left is
> the external reference clocks from outside our own network.
> 
> Parts used:
> Raspberry PI 3
> Adafruit GPS head: ADA-2324
> External GPS antenna with 5 meter cable.
> 
> My NTP config looks like this:
> 
> logfile /var/log/ntpd.log
> logconfig = all
> 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
> server 127.127.22.0 minpoll 4 maxpoll 4 prefer

Your preferred server is just giving you the PPS. With this ref clock you need a preferred server which names the second. So you should move the prefer directive to either your shared memory source , or another local or remote server.

> fudge 127.127.22.0 refid PPS flag3 1
> server 127.127.28.0 minpoll 4 maxpoll 4 iburst
> fudge 127.127.28.0 refid GPS time1 +0.550 flag1 1 stratum 4
> server ntp0.nl.uu.net
> server chime6.surfnet.nl
> server chime5.surfnet.nl
> server ntp1.virtu.nl
> 
> Now I got the idea that I might be able to use a DCF77 receiver to get a
> stable timesource, but on the other hand, if the cause of my problem is
> internal to the Raspberry PI setup then I might have exactly the same
> problem with the DCF77 receiver.
> 
> The average on the NTP clocksource is close to 0.
> root at raspberrypi:/var/log/ntpstats# cat peerstats |grep 127.127.28.0
> |awk '{print $5}'| tail -n 1500 | awk 'NR == 1 { max=$1; min=$1; sum=0 }
> { if ($1>max) max=$1; if ($1<min) min=$1; sum+=$1;} END {printf "Min:
> %d\tMax: %d\tAverage: %f\n", min, max, sum/NR}'
> Min: 0    Max: 0    Average: 0.001101
> 
> Could anyone give me some advice on how to get this working? Or is my
> idea to use a GPS clock to create a stable NTP setup the wrong way to go?
> 
> Thanks for any advice.
> Jan Hugo Prins
> 
> 
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