The physics of a properly run JJA will always produce the same result so you do
not need additional units for comparison.
That is the point of a world wide quantum voltage standard defined as K
J-90 = 483 597.9
GHz/V . Just has the Hyperfine Transition of Cesium at
about 9.192631770GHz is used to define the second. What is neat about the work
NIST has done recently is that it has automated the System for ease of use and
reduced the price to the point that it should see much wider use in day to day
metrology. Having your Agilent 3458A calibrated on a JJA may not yield much
difference over a Fluke 5730A cal, but once the meter has been run a few years
characterizing the A to D converter and 10VAC range would only need to be done
once and could substantially improve performance. I personally think that the
face of calibration will change in coming years, rather then simple time based
cal periods, instruments will contain complex environmental sensor packages
that will constantly monitor the instruments environment . S
o calibration will be based more on the instruments exposure to extreme
conditions then simple time. I bet the act of shipping has more effect on cal
then years sitting in a lab. So if for example a 3458A was put in an
environmental chamber on a shaker table I am sure we find that up to a certain
point enviromental conditions would have little effect on cal but at some point
would have a major effect. Once documented the cals would be based more on
environmental exposure. In addition I am sure some environmental effects on cal
are repeatable and could be documented so if monitored they could be
compensated for extending time between cals. So in the future you would see
your instrument display "environment conditions exceeded" "cal require", with
perhaps even a display of currently instrument uncertainty. This could change
the face of calibration and become a multi-billion dollar industry.
Thomas Knox
> Date: Sun, 16 Feb 2014 07:06:18 -0700
> From: [email protected]
> To: [email protected]
> Subject: Re: [volt-nuts] JJA progress report
>
>
> If Earth is subjected to a GRB strong enough to damage ground based
> electronics,
> we are all going to have much more urgent problems than wondering if a JVS is
> operating properly. Same for an EMP. Lightning, however, might pose a more
> localized and serious threat.
>
> Part of your training as an expert operator will include techniques to
> dissuade
> various critters from considering the JVS for their burial ceremonies.
>
> Carrying your best zener reference to the nearest facility with another JVS
> would be less expensive than buying and operating a second or third system.
>
> Joe
>
>
> On 2/16/2014 12:58 AM, cheater00 . wrote:
> > How do you know the primary standard is not off? That is, how do you
> > know it's still "primary"? Maybe a gamma ray burst from a supernova
> > damaged some of the machinery inside, or a colony of crazy ants
> > crawled in and died inside.
> >
> > D.
> >
> > On Sat, Feb 15, 2014 at 10:10 PM, Joe Hobart <[email protected]> wrote:
> >>
> >> These devices are primary standards; you don't need three; you probably
> >> don't
> >> even need two. If certain conditions are met, conditions you can
> >> check/verify,
> >> they will accurately generate the desired voltages.
> >>
> >> What you will probably want are at least three good zener type voltage
> >> standards
> >> and a constant temperature environment. The three will serve as a day to
> >> day
> >> standard and reality check on the JJA. And you need to really learn how to
> >> operate the JJA standard, so you can detect and correct any problems.
> >>
> >> Joe Hobart
> >> Flagstaff, Arizona
> >>
> >>
> >> On 2/15/2014 1:17 PM, Gordon DeWitte wrote:
> >>> Clearly need three (or some higher odd number) so they can vote...
> >>>
> >>> Gordon
> >>>
> >>>
> >>> On Sat, Feb 15, 2014 at 2:51 AM, Poul-Henning Kamp
> >>> <[email protected]>wrote:
> >>>
> >>>> In message <[email protected]>,
> >>>> Randy
> >>>> Evans writes:
> >>>>
> >>>>> We'll all probably want a spare unit also.
> >>>>
> >>>> Two, how can you know which one fails, if you only have two ?
> >>>>
> >>>> --
> >>>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> >>>> [email protected] | TCP/IP since RFC 956
> >>>> FreeBSD committer | BSD since 4.3-tahoe
> >>>> Never attribute to malice what can adequately be explained by
> >>>> incompetence.
> >>>> _______________________________________________
> >>>
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