A common error discovered in data acquisition systems is to assume that the signal ground and return lines are the same. This often leads to multiple ground links at separate points causing earth currents to flow due to the different parts of the system. The earth currents can be a major contributor to overall system noise. All the equipment connected within a system should all be terminated to one central earth point. The use of proper signal wiring to connect the various transducers to the data acquisition system is essential.
Balanced cables are helpful for rejecting ground difference potentials.
With twisted pair cable, interference is induced on both cables simultaneously, and so effectively cancels out most error incurred the measured signal potential. You may have to use filtering to remove noise from an AC signal. This action can be carried out with hardware dedicated filter packs or via software when post processing the acquired data. Filtering is often used to remove noise components that cannot be prevented by grounding or shielding. This feature is selectable within the driver software and is one of the few instructions that requires selection when configuring one of our instruments.