LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

Acquistion of 1mV signals with NI 6124 DAQ card ?

We re trying to acquire 1mV sinusoidal signals with a NI6124 card

(differential inputs), through a BNC 2090 rack interface.

Input dynamic is -5 +5 V.

Terminal configuration is RSE.

Only one input is connected.

It seems signal distortion (>10%) , dissymetry (> 25%) ,and amplitude modulation, appears below 10mV.  Example snapshots are attached.

Signal is ok on a parallel scope.

Would terminal configuration or input dynamic have an impact on that ?

Is there any other reason why we would observe such distortion/dissymetry ?

Thank you for your answers.

Regards.

Charles.

0 Kudos
Message 1 of 3
(3,017 Views)

1) why RSE not differential?
2) count 50/60HZ on graphs, AM maybe from power wires.

3) why +-5V, not +-1?

0 Kudos
Message 2 of 3
(2,996 Views)

As said, busy trying +-1 V range, for better sampling resolution.

However, if I understood well, measurement could be more impacted

by signal offset in that case, since we're closer to max amp gain.

also trying BNC 2090 differetial set up.

I hope we get better measurement in that case.

Why RSE ?: We try to get best equipotential at PXI input , RSE gathers all

negative signals to ground.

I'm reading at least 10kHz for AM in the snapshots, wonder how you count 50Hz.

Thank you .

Charles.

0 Kudos
Message 3 of 3
(2,951 Views)