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

alkopedia at googlemail.com alkopedia at googlemail.com
Wed Dec 17 16:09:24 UTC 2008


Hi
I have 2 ntp servers running Linux with LinuxPPS patch. Number one
uses a Meinberg PCI511 v1.00 as time source, number two uses a
Meinberg GPS170PCI v1.10.
On both machines ntp is configured to use the Meinberg refclock
(127.127.8.0) and furthermore the Meinberg PPS outputs are connected
to the serial interfaces and use the atom driver (127.127.22.0).
The strange thing is, that there is always a delay of 1-4 ms between
the refclock and the pps signal. In my opinion they should arrive at
the exact same time.

Here is an example graph of the dcf card:
http://img-up.net/img/dcf-delayY6wXrh.png

Here is an example graph of the gps card:
http://img-up.net/img/gps-delayHbRmW6U.png

And here the ntp conf entries:
DCF:
# meinberg dcf
server 127.127.8.0 prefer mode 2
fudge 127.127.8.0 time1 -0.003
fudge 127.127.8.0 refid DCFi
# meinberg dcf-pps
server 127.127.22.0

GPS:
# meinberg gps
server 127.127.8.0 prefer mode 7
fudge 127.127.8.0 refid GPSi
# meinberg gps-pps
server 127.127.22.0

Does anybody else experience this problem or know how I can fix it?




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