Chapter 5, FRONT PANEL OPERATION 
5-58 
5.4.02 Virtual Reference Main Display 
 
Figure 5-44, Main Display - Virtual Reference Mode 
In virtual reference mode, the instrument operates exactly as in single reference 
mode, with the following exceptions:- 
The Main Display always shows the annotation "Virtual Reference Mode" in the 
bottom right-hand section of the display as a warning to the user that this mode is 
being used. 
Although the upper three display positions can be reconfigured to display magnitude 
and/or phase information, neither of these is relevant since there is no reference 
signal to which the phase can be related, and the magnitude equals the X channel 
output. Similarly, controls affecting the instrument's reference phase, such as Ref 
Phase and Ref Phase ±90°, have no effect and are grayed out. 
Harmonics greater than unity should not be used in virtual reference mode since the 
harmonic number relates to the reference frequency. Nevertheless, detection at 
harmonics of the signal frequency is possible by searching for the required harmonic 
frequency. For example, if the signal frequency is 1 kHz and a measurement at the 
second harmonic is required, set the harmonic to 1st and search for a signal at 2 kHz. 
The signals at the OSC OUT connector on the front panel and the REF MON 
connector on the rear panel are at the virtual reference frequency. 
Since none of the controls on the Reference menu are relevant, it is not possible to 
access it.