[ntp:questions] how to have offset < 1ms

lhommedumatch ludocluba at yahoo.com
Wed Apr 14 22:09:18 UTC 2010


On 14 avr, 21:15, Terje Mathisen <"terje.mathisen at tmsw.no"> wrote:
> John Hasler wrote:
> > Richard B. Gilbert writes:
> >> With a closed network the options are limited.  With a place to site a
> >> GPS antenna, you can install a GPS clock that will be accurate to
> >> within +/- 50 nanoseconds.
>
> > It occurs to me that the sort of fancy GPS that an oceanographic ship is
> > sure to have on the bridge may already be capable of providing time
> > service.
>
> The operative word here is _may_. Many (most ?) navigation GPS setups,
> even the fancy RTK models, couldn't care less about providing an
> external PPS signal.
> :-(
>
> Terje
> --
> - <Terje.Mathisen at tmsw.no>
> "almost all programming can be viewed as an exercise in caching"

The ntpgmtaceb (this clock loses 1.10e-11second every second => ie 8.6
10e-7s each days) is providing zda+pps, I have worked on using PPS
with LinuxPPS.
But I need to patch the kernel. I'm using CentOS 5.4 => linux2.6.18.
I have succeeded to work with linux2.6.27 on a ubuntu PC but it's
still experimental and can't be used for operationnal recording.

You all have right, the problem is to have all the devices
synchronized no matter if the time is not correct.
But I'm just responsible for one device. So the problem is how can I
be synchronized to ntpgmtaceb.

Thanks for all this discussion, and I'll need to be at shore to read
all this in a more convenient way.




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