[ntp:questions] no ntp synchronisation: 2s to 6s time shift !

Martin Burnicki martin.burnicki at meinberg.de
Thu Feb 21 16:11:55 UTC 2008


Thierry MARTIN wrote:
> Hi Martin,
> It seems that once again, you're about to save me ;-) !


> So, ok my system has a Meinberg gps170pci board.
> As far as I can remember, when GPS signal is not there, NTP does not use
> GPS refclock as a timesource.

By default not. This is because ntpd sees the board's "not synchronized"
> So i guess, you suggest that I use the DCF77 emulation or some other
> feature from the board?
> Could you please enlight me about this?

It's much easier. You run Linux, don't you?

The kernel module which lets ntpd use the card as reference time source can
be loaded with a parameter which overrides the real board status and always
tells ntpd the card is synchronized. Just load the module with the
following parameter:

modprobe mbgclock pretend_sync=1

Of course this parameter should only be used for testing.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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