[ntp:questions] Meinberg PPS signal is not synchronous with refclock signal

alkopedia at googlemail.com alkopedia at googlemail.com
Thu Dec 18 11:57:32 UTC 2008


On Dec 17, 6:57 pm, ober... at es.net (Kevin Oberman) wrote:
> The time to process the time string from the clock is long and fairly
> slow. The PPS is short and fast. As the documentation states, the PPS
> signal "trains" the clock.
>

OK, my first example has an error. Of course I need the same fudge at
the pps like at the refclock.
As you say it needs time to process the time string from the refclock.
This makes sense to me. So the time string comes a bit to late which
should result in a negative offset to the pps signal.

This is the case for my dcf server:
     remote           refid      st t when poll reach   delay
offset  jitter
==============================================================================
 LOCAL(0)        .LOCL.          12 l    5   64  377    0.000
0.000   0.015
+GENERIC(0)      .DCFi.           0 l    1   16  377    0.000
-0.569   0.687
oPPS(0)          .PPS.            0 l   14   16  377    0.000
-0.003   0.797

The time for processing the time string would be ca. 0.56 ms.

But on my gps server it's different:
     remote           refid      st t when poll reach   delay
offset  jitter
==============================================================================
 LOCAL(0)        .LOCL.          12 l    -   64  377    0.000
0.000   0.015
+GENERIC(0)      .GPSi.           0 l   10   16  377    0.000
1.727   0.015
oPPS(0)          .PPS.            0 l   11   16  377    0.000
-0.009   0.015

Here the reclock has a positive offset of ca. 1.72 ms. This means the
time string was processed faster than the pps signal?




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