[time-nuts] GPSDO+PC as a NTP server

[Bob kb8tq]

Hi

There are a number of GPS errors that turn into “long period” disturbances. A normal 
OCXO (even a good one) runs with a fast enough loop that they do appear in the output
of the GPSDO. One (of many) sources of this sort of error is the 12/24 hour cyclical nature
of GPS orbits. Another is the 24 hour cycle the ionosphere goes through ….. 

Bob

> On Oct 25, 2019, at 2:09 AM, Adam Kumiszcza <akumiszcza at gmail.com> wrote:
> 
> Hi!
> 
> Thanks for all the responses. As I wrote, the chip can use only 1
> constellation, and I'm not sure it can use Galileo at all, so I'm sticking
> to GPS only. As I understand it, GPS errors here smooth out anyway while
> disciplining internal OCXO, so it's not so important to have the best chip
> available. I guess u-blox zed-f9t with a bad ocxo would be worse than
> normal u-blox 7 with a better ocxo? I intend to run it 24h/day BTW.
> 
> As for FreeBSD, I like this system a lot, too. Especially for proper native
> ZFS support. I use it mainly for NAS now, but experimented with different
> versions before, so I guess I'll go this route. Does Lady Heather compile
> on FreeBSD? And is it possible to run it together with NTP for the same
> rs232 port? I found this:
> https://www.febo.com/pipermail/time-nuts/2010-February/044476.html  – but
> it's for thunderbolt and at "very early, rough stage". I would like to
> attach a small monitor and have LH run there constantly.
> 
> BTW, Fiorenzo Cattaneo, I did not get the picture of your set with
> pcengines box. Probably got cut by mailing list.
> 
> Best regards,
> Adam Kumiszcza
> 
> On Fri, Oct 25, 2019 at 2:01 AM Charles Steinmetz <csteinmetz at yandex.com>
> wrote:
> 
>> Bob wrote:
>> 
>>> The “ideal” solution (at least to me) would be a setup that let you
>> estimate the time based
>>> on each system independently. Even things like survey locations vary a
>> bit system to system.
>>> Give each one the “fix” that it thinks is best and go from there. Then
>> report the output PPS time
>>> offset for each of them. Let “higher authority” decide what to make of
>> the results.
>> 
>> Well, heck, if you can count on divine guidance, what do you need the
>> GPSDOs for?   ;-)
>> 
>> Best regards,
>> 
>> Charles
>> 
>> 
>> 
>> 
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