What are 6.5 Digit Multimeters Good For?

Measuring to PPM accuracy, and measuring microvolt-level voltages. And as a traceable standard for calibrating products.

The Fluke 8845A is excellent.

John

Sometimes you need to measure a knats ass.

What's the big deal? Can't they just switch to 24-bit ADC's on the cheap and get the accuracy? Or is there some special techniques required to get that resolution in practice?

A 2.5 digit meter can measure a knats ass. A 6.5 digit multimeter would be for measuring the presense of a knats ass while weighing a whale.

Measurement precision and accuracy aren't the same. You mix "resolution," "accuracy," and "24-bit" in the same breath.

Jon

Ah.. the tool that sets the tools.

Of course there's always something better.. :P

It's probably trouble to push the noise floor down with the front end electronics in the multimeter.

Your a freaken genius!

I read that this is not difficult by paralleling ADC's or using averaging. Since the noise generally is symmetric(generally gaussian) by averaging it will cancel out.

I guess it is more important that the ADC be stable but as long as any fluxuations are symmetric(such as clock jitter) then averaging should take care of most of the problems.

Yes, but maybe that is due to the scope not using that 32-bit ADC? ;)

Who is "they"?

An ADC needs a voltage reference and, generally, front-end differential amplifiers, filters, and attenuators. And to be a DVM, it needs a user interface, a display, and a data interface. Oh, power supplies too.

If it does AC and ohms, it needs more stuff.

John

D from BC wrote in news:MPG.26034c831878edc69896e6@209.197.12.12:

and they generally have better AC volt accuracies.

the HP/Agilent 14401A is better. :-)

it's not how many digits in the display,it's how ACCURATE the meter is that matters.

Some years ago, a guy in one of the audio forums suggested that audio really ought to be recorded and delivered using 32-bit PCM, "just to make sure."

I pointed out that if one were to set the playback amplitude so that a least-significant-bit signal produced audio at the listening position equal in power to the random thermal noise of air molecules hitting the eardrum, a full-scale 32-bit signal would vaporize the power lines, explode the building and kill the listener :-)

True.. My scope has 8 bit voltage resolution. The point I was trying to get across was if an 8 bit system shows it's noise floor then it's probably gets increasingly difficult to control noise as sytem resolution increases(16,24,32).

That's seems like the averaging feature on oscilloscopes... Given time, the signal cleans up nice.

But have no clue as to why.

Try Keithley

Which is why Keithley is better.

Agilent is good, don't get me wrong.

Don't be a LarkinTard. Instead of a lard ass, he is a Tardass.

Fleas and lice are smaller. Some have even invaded this group unseen by most.

Damn! The little bastard actually said something quite intelligent!

I am impressed... really.