[ntp:questions] using both a PPS source and a HBG (dcf-77-like) timesource?

Folkert van Heusden folkert at vanheusden.com
Mon Jan 14 16:21:29 UTC 2008


> > day, but I think that was for long distances, bouncing off the
> > ionosphere which changed height at night.  I'd expect it to be
> > pretty stable if you are close to the transmitter - ground wave.
>
> HBG is in Switzerland if I remember correctly, and from your post, you are 
> in Netherlands,

correct

> so you can estimate propagation delay. However, I don't see 
> why you would want to use an LF reference of lesser accuracy and estimated 
> delay when you can use GPS.
> Just a thought.

Well if I remember correctly someone said to me once that the
time-string returned by cheap gps device (like my garmin 18 lvc)
sometimes is a bit off while its PPS signal is fine.

Currently I'm syncing against NMEA/PPS and seeing quiet a big offset:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
xGPS_NMEA(0)     .GPS.            0 l    7   16  377    0.000  -185.08   1.001  <---
 PPS(0)          .PPS.            0 l    -   16    0    0.000    0.000   0.001  <---
-muur.intranet.v .DCFa.           1 u    5   64   77    0.072   -9.207   0.023
-thegateap.intra .SHM.            1 u   46   64   37    0.873    0.931   0.045
 SHM(0)          .SHM0.           2 l    -   64    0    0.000    0.000   0.001
 SHM(1)          .SHM1.           2 l    -   64    0    0.000    0.000   0.001
 SHM(2)          .SHM2.           2 l    -   64    0    0.000    0.000   0.001
 SHM(3)          .SHM3.           2 l    -   64    0    0.000    0.000   0.001
 NTP.MCAST.NET   .MCST.          16 u    -   64    0    0.000    0.000   0.001
 192.168.64.0    .BCST.          16 u    -   64    0    0.000    0.000   0.001
-auth1.xs4all.nl 194.109.22.19    3 u   48   64   77    7.945    1.514   1.158
-auth2.xs4all.nl 193.67.79.202    2 u   46   64   77    9.450   -0.893   0.713
+ntp1.nl.uu.net  .GPS.            1 u   45   64   77   13.693    0.173   9.097
*chime2.surfnet. .GPS.            1 u  111   64   76   12.262    0.387   1.092
-superboer12.stu 193.79.237.14    2 u   45   64   77   13.012    4.401   2.248
+ntp.networking4 193.190.230.65   2 u   46   64   77    9.242    0.444   0.494
+mailer.zylom.co 193.190.230.65   2 u   44   64   77    9.040    0.430   0.538
-aivd.xelerance. 193.0.0.228      2 u   41   64   77    8.881   -0.610   3.154

Folkert van Heusden

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