[ntp:questions] Leap second and refclock

Hans Jørgen Jakobsen hjj at wheel.dk
Tue Jul 10 16:53:07 UTC 2007


On Tue, 10 Jul 2007 10:25:44 +0200, Jon K Hellan wrote:
> We made a new refclock, which seems to be working well, but are not
> sure what will happen when the next leap second comes along. Advice
> would be appreciated.
>
> Background: Our passive network monitoring computers use DAG
> monitoring cards from Endace. These cards are GPS synchronized and
> have a highly stable on board clock. This results in a very accurate
> clock on the DAG card. To have a good clock on the rest of the
> computer, we discipline NTP to GPS.
>
>      _
>     / \ GPS
>      |                      Monitoring computer
>      |        +---+        +-------------------------+
>      +------+-|   |--------|Serial input             |
>       RS-422| +---+ RS-232 |                         |
>             |              |                         |
>             +--------------|DAG monitoring card      |
>                     RS-422 +-------------------------+
>
> The configuration we have been using is shown above.  The GPS units
> are Trimble Acutime 2000.  We are bringing RS-422 from the Trimble to
> the DAG card, and RS-232 to the serial port. NTP uses the Trimble
> Palisade refclock and talks the Trimble event stamping protocol to the
> GPS.

Driver 43 (ripencc) is an alternative driver that are not using polling.

>
> For various reasons, we want a simpler setup. For one, Trimble seems
> to have dropped the Acutime 2000. The successor, Acutime Gold, comes
> with an RS-422/USB converter instead of the RS-422/RS-232 one. It is
> also getting harder to find severs which have RS-232 inputs. Finally,
> we would like to have fewer points of failure.

As far as I read its only the RS-232 version and NOT the RS-422 that
is discontinued: http://www.trimble.com/tmg_acutime2k.shtml

USB is polled and that will create problems.
/hjj




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