Below is a system where a signal source on the left is floating/ungrounded/unearthed and the measurement system on the right is earth-grounded through the signal analog ground AGND:
Regarding the above setup I have the following questions:
Is there still change for a ground loop to occur through earth coupling?
If there would be earth coupling through parasitic capacitance, would that be a type of common mode noise?(Would that couple to both AGND and signal line?)
I see always one side recommended to be earth-grounded. What would be the disadvantage of making both signal and measurement sides unearthed?