Noisy signal reading using PCI-6036E

[ChuckNRC]

Hi.  I'm using a PCI-6036E multifunction DAQ card and an SCC-2345 with a SC-AI03 (+/- 10V input).  My question is, what sort of accuracy should I expect from such a setup?  Right now I have a signal that is essentially 0-10V and it seems to be accurate to about 2 decimal places. 

I realize that noise can creep in from a variety of sources, however I don't believe I'm getting noise from anything external (ie other electronics or equipment).  I don't think I'm in an electronically noisy environment.  I've measured the voltage with a relatively cheap fluke multimeter and that seems to be good to at least 3 decimal places.  I can filter the data which I have and sure it is somewhat cleaner, however I would have expected better results than I'm getting without resorting to filtering.  As it stands I'd like to be able have at least one more reliable decimal place of accuracy.

I also made sure to hookup a resistor (10K) from pin 3 of the SC-AI03 to the AI sense line, but that didn't seem to make any difference.  I also tried a few other resistor values, just to see if there was any difference, but no luck.

Anyone have any experience with the above sort of equipement?

Thanks

Chuck

[Hal_L]

Hi Chuck,

When you say that you're measurements are only accurate to two decimal points: is the third decimal point constantly fluctuating or are you only getting two decimal points back as your data?

Also, here are a couple of knowledgebases, including one with a link to an online accuracy calculator, that you might find helpful:

How Do I Calculate Absolute Accuracy or System Accuracy?

Field Wiring and Noise Considerations for Analog Signals

Regards,

Hal L.