3Instrument Configuration88Keysight U8903A User’s GuideRef/RelThe Ref/Rel section sets the reference impedence, voltage, frequency, and ratiovalues depending on the type of reference to be set for unit conversion. There arethree available types consisting of Level, Frequency, and Ratio.For the relative level values, the level measurement can be displayed in Off mode,Log mode (dBr), or Linear mode (x).Figure 3-14Reference Level