[time-nuts] Clock accuracy

paul swed paulswedb at gmail.com
Fri Jul 19 13:34:19 UTC 2019


Jim
Boy did you actually hit the issues.
I have run into all of them. The bearings are a real issue.
I have one clock I need to pull down and lube. Pain in the butt.
Regards
Paul

On Fri, Jul 19, 2019 at 9:20 AM Jim Harman <j99harman at gmail.com> wrote:

> Somewhat tongue in cheek, from another relative beginner:
>
> There are also several seconday effects you will need to consider over the
> next 100 years:
>
> -- Do you have a way of changing the battery in the clock without it
> stopping?
> -- Will the $10 clock's bearings last 100 years?
> -- If the 1 pps output from your GPSDO comes directly from the GPS, and not
> by dividing down the oscillator, how will you handle holdover events, when
> it may skip some pulses?
> -- Is the adjustment range of your oscillator sufficient to compensate for
> 100 years of drift?
> -- Will the other components in your GPSDO (esp. electrolytic capacitors)
> last 100 years?
> -- Will the GPS system still be operating 100 years from now, or will it go
> the way of LORAN? You might need a provision for seamlessly switching to a
> different 1-pps source if the technology changes.
>
>
> On Fri, Jul 19, 2019 at 5:10 AM Hal Murray <hmurray at megapathdsl.net>
> wrote:
>
> >
> > > If I live another 100 years [Let`s say I take antioxidants ;-)  ] what
> > sort
> > > of error should I expect in this clock? [I know that it`s better than 1
> > > second per day]
> >
> > You didn't say anything about skipping leap seconds.
> >
> > Ignoring that part, and assuming you have a good antenna, and assuming
> the
> > GPS
> > operators don't screwup and/or that your GPSDO has good enough holdover,
> > it
> > will be right on.
> >
> > Your system is tracking GPS.  So the next question is what do you expect
> > your
> > clock to be tracking?  If you want to track UTC, then you need to
> research
> > the
> > offset between GPS and UTC.  (Hint: It's not very big.)
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> >
> >
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>
>
> --
>
> --Jim Harman
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