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 <[email protected]> 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 <[email protected]> > 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" < > [email protected]> > > To: "Discussion of precise voltage measurement" <[email protected]> > > 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 <[email protected]> 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. > >>> > >>> > >>> _______________________________________________ > >>> volt-nuts mailing list -- [email protected] > >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ > >>> mailman/listinfo/volt-nuts > >>> and follow the instructions there. > >>> > >> _______________________________________________ > >> volt-nuts mailing list -- [email protected] > >> To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > >> and follow the instructions there. > > > > _______________________________________________ > > volt-nuts mailing list -- [email protected] > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > > and follow the instructions there. > > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
