[ntp:questions] LOCL clock reachability not 377?

Rob nomail at example.com
Thu Jul 31 16:44:55 UTC 2014

Martin Burnicki <martin.burnicki at meinberg.de> wrote:
> This sounds good. I think we'd have to distinguish some basic cases a 
> few of which immediately come to my mind:

It looks good.

What is important for my box (but maybe only for mine...) is that there
is some method to feed OK/FAULT status to ntpd without a reference clock
driver, or with a reference clock driver that ntpd understands will not
provide time but only status.  That driver could be similar to SHM
(or it could be SHM with a fudge flag set), in that it could use a
shared memory segment where an external program puts a flag indicating
the validity of the PPS source.

My GPSDO is very good at providing PPS and 10 MHz, but otherwise it is
old and rusty.  Apparently many of them are going around in hobbyist
circles.  It does provide IRIG output, but that is not really useful as
you already indicate (and difficult to interface as well), and an RS232
command/status interface that only provides UTC/GPS time but no date.
However, on that interface there is a good indication of the search/lock
status and the momentary (estimated) error, which I use to generate
nagios alerts when it goes haywire.  For that, a daemon is running that
polls it every few seconds, which could be extended to write the SHM flag.

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