Configuring the internal baseband source
R&S
®
SMM100A
115
User Manual 1179.1341.02 ─ 05
4.5
Generating custom digital modulated signals
The R&S
SMM100A can generate digital modulation signals with user-definable char-
acteristics. The baseband filtering and the symbol rate can be set within wide limits.
4.5.1
Required options
The equipment layout for generating the digital modulation signals includes:
●
Option Baseband Generator (R&S
SMM-B9)
●
Option custom digital modulation/baseband realtime extension (R&S
SMM-K520)
4.5.2
About the custom digital modulation
An introduction to the supported filter, modulation, and coding schemes are provided
in:
●
Chapter 4.4.1.6, "Supported baseband filters"
●
Chapter 4.4.1.4, "Supported modulation signals"
●
Chapter 4.4.1.5, "Supported coding schemes"
Interdependency between selected modulation type and coding scheme and
handling of conflicting settings
The applied coding is directly related to the selected modulation methods. The availa-
ble coding schemes listed in
Chapter 4.5.5.1, "Common coding algorithms"
on page 140 are not freely combinable with modulation methods.
Obviously, having selected a modulation procedure, not every combination of the fur-
ther modulation parameters "Symbol Rate" and "Coding" is possible. These restrictions
inevitably result in conflicting settings if you change a parameter and leads to a prohibi-
ted combination.
An inappropriate change of a parameter triggers a settings conflict, which is indicated
by a message on the "Info" line in the display. Although the R&S
SMM100A displays
the selected settings, the generated modulation signal does not correspond to this dis-
play. The displayed message disappears when a conflict-free setting is selected.
Refer to
Chapter 14, "Troubleshooting and notifications"
possible settings conflicts and messages in digital modulation.
4.5.3
Custom digital modulation settings
Access:
► Select "Baseband > Custom Digital Mod".
The "Custom Digital Modulation" dialog enables direct selection of the data source,
standard, symbol rate, coding, modulation type and filter.
Generating custom digital modulated signals