RIGOL  Chapter 2 Front Panel Operations 
2-46     DG800 User's Guide 
To Set the Modulation Polarity 
 
Tap the Polarity parameter selection field to select "Positive" or "Negative" polarity 
of the modulating waveform to control the output amplitude. 
 
In the internal modulation, set the polarity to "Positive", and the generator will 
output an amplitude whichever is smaller between the carrier amplitude and 
modulating amplitude when the modulating waveform is a logic low level. It will 
output an amplitude whichever is greater between the carrier amplitude and 
modulating amplitude when the modulating waveform is a logic high level. The 
situation is the opposite when the polarity is set to "Negative". 
 
In the external modulation, set the polarity to "Positive", and the generator will 
output an amplitude whichever is smaller between the carrier amplitude and 
modulating amplitude when the external input signal is a logic low level. It will output 
an amplitude whichever is greater between the carrier amplitude and the modulating 
amplitude when the external input signal is a logic high level. The situation is the 
opposite when the polarity is set to "Negative".