[volt-nuts] Basic question concerning voltage references

[Russ Ramirez]

Thanks Jerry, I'll give that a try later just to see what it does :-)

Russ

On Mon, Feb 20, 2017 at 2:53 PM, Jerry Hancock <jerry at hanler.com> wrote:

> You can get 7.5 digits using the HIRES register over GPIB or by using the
> stat function from the front panel.
>
>
> > On Feb 20, 2017, at 11:33 AM, Tom Miller <tmiller11147 at verizon.net>
> wrote:
> >
> > I believe you can get 7-1/2 digits out of the 3457A via the HPIB port.
> >
> > Regards,
> > Tom
> >
> > ----- Original Message ----- From: "Russ Ramirez" <
> russ.ramirez at gmail.com>
> > To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
> > Sent: Monday, February 20, 2017 2:26 PM
> > Subject: Re: [volt-nuts] Basic question concerning voltage references
> >
> >
> >> My question is partly based on a real situation where I have 3 DMMs of
> >> decent quality Keithley 2000, 34970A (34401A), and 3457A that all agree
> >> with a good quality voltage reference that is exceeding its ppm/degree C
> >> spec as far as I am able to tell. I felt that this was telling me that I
> >> would need a 3458A to know how much closer to 10V the reference was at
> this
> >> point. A quick calculation of 20 bits of ADC for example told me that I
> was
> >> looking at 9.5 uV of resolution, or 0.6 uV at 24 bits *noise free*,
> etc. so
> >> it did not seem to be entirely unreasonable to see the LSD of a 6 1/2
> digit
> >> DMM be higher than 1 or 2 counts.
> >>
> >> Russ
> >>
> >> On Mon, Feb 20, 2017 at 12:57 PM, m k <m1k3k1 at hotmail.com> wrote:
> >>
> >>> On 20/02/2017 18:46, Russ Ramirez wrote:
> >>> > I very much enjoy what is shared here. It has led me down the path of
> >>> > learning more about Metrology in general and the pointers to Flukecal
> >>> site
> >>> > from here are appreciated.
> >>> >
> >>> > My question is this. If I measured a 10 volt reference known to be
> good
> >>> to
> >>> > 8 1/2 digits, but with the LSD being > 0, assuming a transfer
> standard
> >>> with
> >>> > traceability and documented uncertainties etc, would a 6 1/2 digit
> >>> > voltmeter read 10.00000 volts, or round up to the limits of its AD
> >>> > converter resolution; say X uV over 10.00000 volts?
> >>> >
> >>> > I hope this is not too basic a question.
> >>> >
> >>> > Russ
> >>> > _______________________________________________
> >>> >
> >>> Hi Russ,
> >>>
> >>> some voltmeters will supply extra digits in the output they provide,
> but
> >>> whether they are of any use depends upon how
> >>> stable the reference is in that particular 6.5 digit dvm,
> unfortunately it
> >>> needs a dvm with better capability to prove
> >>> if those digits are believable.
> >>>
> >>>
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