[volt-nuts] 3458A calibration

[WarrenS]

OK, So it is not the best or most accurate technical phrase to use. 
My Smoke and mirrors name, was just meant as another name for an apparent 'Magic' trick, that is not magic at all once it is understood.
When it is realized that there is no such thing as a voltmeter, There are just a ration meters, Then you can leave the details of how it scales the RATIO up to S/W.
The 3458A thru a couple of internal steps uses the 7 volt reference as the ratio for the ADC. And its accuracy is maintained by doing regular recalibrating.  

Speaking of How they Automate things
There are many manual ways to get a perfect +1 to -1 ratio, Anyone know exactly How the negative readings are rationed & referenced to the positive readings in the 3458A?.

ws

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In message <C47F9916CFA44E109C8BCFA00E0C8DF2 at WSOffice>, "WarrenS" writes:
>Randy
>
>The general way it is done is mostly with "smoke and mirrors',
>otherwise known as Software scale factors and offset numbers.

Calling it "smoke and mirrors" sounds weird in my ears: they have
merely automated what you would have done manually to reach the
same level of precision otherwise.

The main difference is that the 3458A *also* gives you a very
fast data-collection/digitizer, which, instead of being calibrated
by twisting trimmers, is calibrated using the same math as is
used for the metrology grade instrument in the same box.

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