I am running a PXI 4071 DMM in a CXI-1033 chassis for voltage measurements in the low microvolt range. Unfortunately, I observe a signal noise of 10 µV and also a longer wavelength fluctuation of the baseline.These effects are not from the application but from the measurement. I have noticed that even small temperature variations have a big influence on the measurement signal. I have also tried different settings with noise reduction (DMM) and fan (Auto ot High) of the PXI 1033 chassis and found no significant change. Does anyone have experience and can give me a tip on how I can improve the baseline?
Your statement about temperature variations influencing measurement signal points me to the Seebeck effect, do you have a lot of dissimilar metal junctions along the wiring?
Even relays in the circuit cause these because relays contacts are copper and solder joints are alloys. What are you measuring and how does the measurement setup look like?