Here is a BSD computer running ntpd, configured with hardware serial port
attached GPS, PPS through FatPPS into the serial port seen as GPS_NMEA below,
along with the two LeoNTP servers at 192.168.20.5 and 192.168.20.6, offset and
jitter appear reasonable, as expected on a LAN, and I've seen no anomalies over
the past month.
remote refid st t when poll reach delay offset jitter
==============================================================================
oGPS_NMEA(0) .GPS. 0 l 20 16 377 0.000 0.002 0.001
<- BSD+PPS
+192.168.20.5 .GPS. 1 u 24 64 377 0.162 -0.011 0.006
<- LeoNTP #1
+192.168.20.6 .GPS. 1 u 44 64 377 0.159 -0.009 0.004
<- LeoNTP #2
The three devices above have separate GPS antennas installed within a couple
meters of each other, all three see between 10 and 12 satellites.
A couple weeks ago I also used an HP 5334B to compare each LeoNTP PPS to a TVB
screened T-Bolt PPS, the T-Bolt was configured with LH extended location
calibration and in over-determined time mode, T-bolt sees 7 or 8 satellites.
Each LeoNTP 1PPS BNC output agreed with the T-Bolt 1PPS to within some tens of
nanoseconds over a 30 hour run. The LeoNTP and T-Bolt shared a Microsemi gps
splitter and the same antenna.
After reading your email, as a final sanity check we just set up a Linux ntpd
configured with both LeoNTP servers along with four random us ntp pool servers.
After an hour here is ntpq -p.
remote refid st t when poll reach delay offset jitter
==============================================================================
+192.168.20.5 .GPS. 1 u 46 64 377 0.604 -0.059 0.123
*192.168.20.6 .GPS. 1 u 40 64 377 0.602 -0.050 0.116
-x.ns.gin.ntt.ne 249.224.99.213 2 u 528 1024 377 12.232 2.023 10.209
xclockb.ntpjs.or 132.163.4.101 2 u 421 1024 373 61.785 2.924 0.244
+four10.gac.edu 216.218.254.202 2 u 1017 1024 377 63.364 -0.137 0.381
-c-73-37-183-90. 142.66.101.13 2 u 418 1024 377 64.903 1.928 2.507
In the above, 192.168.20.5 and 192.168.20.6 are each LeoNTP, they agree with
the four pool servers as nicely as can be expected with a cable modem
connection.
Summary: I do not see any issues with the LeoNTP servers, both devices worked
as expected. LeoNTP is also by far the friendliest commercial NTP server I've
ever configured, the human interface is well thought out.
As Hal suggested, perhaps there is some systematic configuration issue with
your other pair of clocks? I keep a $40 Adafruit Ultimate GPS with PPS output
and little puck antenna, for the sort of situation you see, it powers up
indoors in 60 seconds and its PPS into ntpd would let you have a 3rd clock if
using internet servers doesn't get you an answer.
I have no relationship with the vendor other than as a satisfied customer.
Bob
> On Oct 14, 2016, at 5:31 PM, gmx tallahassee <[email protected]>
> wrote:
>
> Hi all,
>
> I'm checking out the leontp ntp time server (leontp.com). After a week of
> use I am getting the following ntp -q output:
>
> $ ntpq -pn
> remote refid st t when poll reach delay offset
> jitter
> ==============================================================================
> *172.17.21.11 .GPS. 1 u 13 16 377 0.137 0.077
> 0.054 <- Arbiter 1084C GPS Clock
> +172.17.21.12 .GPS. 1 u 11 16 377 0.101 0.085
> 0.174 <- Arbiter 1084C GPS Clock
> x172.17.21.233 .GPS. 1 u 11 16 377 0.071 9.760
> 0.061 <- LeoNTP
>
> the offset of the leontp device from the other clocks has consistently been
> in the 9.5 -10.5 range. since I'm measuring all three sources from the
> same (EL7) computer, I would expect that the offset of the leontp unit to
> converge to be in the close neighborhood of the offsets of the arbiters.
> It has not converged, instead maintaining the ~10ms offset.
>
> Thoughts?
>
> Thanks.
>
> Details:
>
> 172.17.21.11 is approx 400M away through two Cisco 3750G switches no
> routing.
> 172.17.21.12 is in the same rack as the leoNTP unit and plugged into the
> same 3750G switch
>
> Antenna location for the .12 arbiter and the leontp is on the same rung of
> the same tower. Tower has clear horizon to horizon view. cable runs are
> the same (obviously).
>
> I did run with the included puck in my south facing office window (rather
> than the GPS antenna on the tower) for a couple of days when I first got
> the unit. The offset behaviour was the same.
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