Hi @aneeseyerov,
It would help if you can explain a bit more about your setup.
Are you trying to measure the voltage drop of the communications signals, or is the tether providing power to the ROV? And if the latter, what kind of voltage are you putting into the tether, and is it undergoing a step up / step down on either end of the tether?
In case it’s relevant, this thread discusses configuring a second power monitor in the autopilot, which can then typically be displayed in your control station software, although if you’re measuring a high voltage then you may need to measure it through a voltage divider using some high value resistors.