How to determine measurement accuracy required by a source.

[epsilon-delta]

I have a DUT that has a certain accuracy specification and I want to make a measurement to see if the device meets the accuracy specification.

So I will input a signal from a calibrated source to the device.

The question is, what is the minimum accuracy specification required for the calibrated source?  I assume the minimum accuracy would be expressed in terms of the specified accuracy of the DUT.  This is important because the accuracy of analog output boards is different, and I need to choose a board with the correct accuracy for my test.

Someone once told me that there is a Six-Sigma Black Belt rule of thumb that the source or measurement device should have an accuracy that has at least 3 times the accuracy of the input being excited or the output being measured, but I have not been able to confirm this.

Any help would be much appreciated.

Thanks.

[Dennis_Knutson]

This is the wrong board for your question. Measure is an obsolete product from NI and this board is not a generic dumping place for questions.