noise reduction 2

[fhkoeln]

I am reading again my PT100 and I have checked that the offset of my DAQCard 6024E is OK. But even when I use differential mode and my current source is very clean and stable, my readings are moving in the range of 200 µV. I also use dithering. Does have sense to use dithering and also to average the samples? I ask because for me dithering is a kind af averaging. I expect a precision of around 25 µV, according to the manual for such a 12 bit card, for an input range from -50mV to +50mV but my readings are changing in a wider range. Am I expecting too much from this DAQCard? The bias resistors I use are of 1 KOhm (100 times the nominal value of a PT100). Would help to amplify externally my volatge signal? Thanks in advance, I am very grateful for the an
swers from this forum.

[Filipe A.]

Hello;

Since you are workin with a fairly low voltage signal, if you could condition the signal before it go in the DAQ card, that would help the precision of the final readings. I think a simple amplification would help.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments