Configuring the RF Signal
R&S
®
SMW200A
532User Manual 1175.6632.02 ─ 30
8.8.2.2 External Signal Sources
For the input of an external amplitude, frequency or phase modulation signal, you can
assign the signal at the EXT x connectors.
External pulse modulation signals are fed via the global connectors, assigned in the
"Global Connector Settings" dialog, see Chapter 12.2.5, "Global Connectors Settings",
on page 724.
The external modulation signal at the input must have a voltage of U
S
= 1 V (U
EFF
=
0.707 V, in case of sine signals) to achieve the displayed modulation depth and range.
The input voltage should not exceed 1.1 V, otherwise modulation distortions might
occur. With external pulse modulation, the switching point is max. 2.4 V and the volt-
age at the input should not exceed 5 V. The maximum modulation frequency is 10 MHz
for frequency and phase modulation.
8.8.2.3 Assigning the LF Signal to the Output
The R&S SMW can also act as the source for modulations in downstream equipment.
Regardless of the used signal source, which can be the internally generated or an
externally fed LF modulation signal, you can optionally select the signal for output. The
LF signal is output at the LF OUT x connectors.
Note that the output of the internal LF signal and the analog I/Q signal use the same
physical connectors (LF OUT x and I/Q out x), that means these signals cannot be out-
put simultaneously. If both, the I/Q and the LF signal output are switched on, the I/Q
signal is suppressed and the instrument provides the LF signal.
You can freely assign the LF signals from both paths (A or B) to the outputs. To per-
form the assignment, use the "LF Output" tab. It is available both in the "Modulation"
dialog of path A and path B, but the functionality applies to both paths the same way.
Therefore, the instrument adjusts your settings always in parallel. The "Overview" tab
shows the current configuration graphically, and allows you to modify the assignments
there directly. The assignment of the shown LF output is of course in both paths the
same.
Since there are two LF output connectors, but the R&S SMW can process multiple LF
signals simultaneously, there are some configurations that exclude each other.
See the following examples to the overview tab, the versatile options for configuring
the modulation signals and the graphical representation of the signal flow.
Example: Introduction to the "Overview" tab
This example briefly explains the view and the elements of the "Overview" tab of the
two paths (A and B). The tab shows the two common LF output signal connectors,
which are the same in both paths, and the specific modulation settings of the respec-
tive path. Active signals are indicated by a blue output box.
Analog Modulations
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