[ntp:questions] LOCL clock reachability not 377?

Martin Burnicki martin.burnicki at meinberg.de
Fri Aug 1 12:56:49 UTC 2014


Rob wrote:
> Martin Burnicki <martin.burnicki at meinberg.de> wrote:
>> This could basically work with all types of refclock, e.g.:
>>
>> # refclocks with PPS signal and status, but no absolute time
>> server 127.127.8.0 noselect
>> server 127.127.22.0 stat 127.127.8.0  # sync state from parse driver
>>
>> server 127.127.28.0 noselect
>> server 127.127.22.1 stat 127.127.28.0  # sync state from SHM0
>
> Ok that looks good, but I have to check if it is possible to relay
> status information through the SHM driver in a reasonable way.
> (just put a valid time of zero in the clock for valid, and stop
> putting time values in the clock for invalid?  is that what you
> have in mind?)

This was just an example. Since the PPS driver by itself is unable to 
retrieve the status (it also wouldn't kno how to do it) using one of the 
other existing refclock which already support this came into my mind.

Anyway, the details would have to be checked for any refclock driver 
which should nbe used to pass the status only.

How have you done this before?

>>> 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.
>>
>> In the example above the daemon could also just write the sync status to
>> the SHM segment. Since the "noselect" keyword is given ntpd would poll
>> it but not try to use it as normal refclock.
>
> Yes but if I remember well the SHM clock does not have a sync status,
> only a timestamp can be written there and a flag set that this has been done,
> which will be seen by ntpd and reset again.

I'm actually already out for the weekend, and will have limited internet 
access the next days, so I'm currently unable to look at this in more 
detail, and my replies may also be delayed for the next days.

Martin
--
Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont
Germany



More information about the questions mailing list