Rohde & Schwarz SMM100A, User Manual

Page: 286 / 1088

Applying I/Q vector modulation
R&S
®
SMM100A
286 User Manual 1179.1341.02 ─ 05
System error correction of the I/Q modulator permits precise and repeatable measure-
ments.
If a temperature fluctuation of several degrees occurs, trigger the correction routine
using the following:
●
Select "I/Q Mod > I/Q Modulator > Adjust I/Q Modulator Current Frequency"
Settings:
State ............................................................................................................................286
Source .........................................................................................................................286
I/Q Swap ..................................................................................................................... 286
I/Q Wideband .............................................................................................................. 287
Crest Factor ................................................................................................................ 287
Baseband Gain ........................................................................................................... 288
Optimization Mode ...................................................................................................... 288
Linearize RF ................................................................................................................289
Adjust Linearization Current Frequency ......................................................................289
Adjust I/Q Modulator Current Frequency .................................................................... 289
State
Activates/deactivates I/Q modulation.
Note: Interdependency. If "Source > Internal Baseband", the I/Q modulator is always
activated automatically when signal generation is activated ("Baseband > State > On").
I/Q modulation can, however, be deactivated later, e.g. if the relevant signal is the
baseband signal and it is directly routed to the I/Q outputs.
Remote command:
[:SOURce<hw>]:IQ:STATe
on page 896
Source
Selects the input signal for the I/Q modulator. Refer to Table 6-1 for an overview of the
possible input signals and the connectors they are supplied at.
"Internal Baseband"
Selects the internal baseband signal.
"Analog Wideband I/Q Input"
Selects an external analog signal.
Remote command:
[:SOURce<hw>]:IQ:SOURce
on page 895
I/Q Swap
Selects normal or swapped I/Q control for the generated signal.
The I/Q modulator defined in the IS2000 standard differs from the definition in this
implementation. The definition on which the implementation is based is used by virtu-
ally all digital communication standards, except IS95 and IS2000.
In the final step, the filtered IQ signal is modulated to the desired RF in a different way
in the I/Q modulator:
I/Q modulator settings