Need detailed information on GND and AGND on the USB-1808X card

[Per]

I am using the USB-1808X and it is performing well but I still have some Noise on the analog input signals and I would like to know more about how the "GND" and "AGND" are connected internally. Does the negative side of the 5 volt provided by the USB cable carry over to the signal side?

I also suspect that my computer contributes some noise via the shield on the USB power cable, is it possible to use clamps on ferrites to reduce this contribution?

 

Best from Per Ohlin

CEO, ADEC Automation AB

Vice President, BATIXT AB

[DAQman]

I apologize for the late response. GND and AGND are connected on the PCB board.  However, the AGND path is meant for analog grounds only. Digital grounds tend to have switching noise, and running separate paths reduces overall measurement noise. 

On the other hand, a ground loop can appear as a noisy signal. If you suspect a ground loop, use a differential connection instead of a single-ended one.