Configuring the Internal Baseband Source
R&S
®
SMW200A
248User Manual 1175.6632.02 ─ 16
ated with the Rohde & Schwarz software tool mapping wizard. The mapping wizard
(mapwiz) is a tool from Rohde & Schwarz designed for editing modulation schemes
(for example QPSK, 32QAM). Its main purpose is the assignment of logical symbol
numbers to constellation points and the selection of modulation-specific parameters.
Beyond this, it supports the creation of nearly any arbitrarily chosen constellation dia-
gram. The output of mapwiz is a mapping file (*.vam) that can be imported to a
R&S SMW. The program was developed on a 32-bit Microsoft Windows platform under
MATLAB. For more information, refer to the description "Introduction to "mapwiz" Map-
ping Editor" at the Rohde & Schwarz webpage.
The remote commands required to define the modulation settings are described in
Chapter 13.18.4.2, "SOURce:BB:DM Subsystem", on page 890.
Related settings:
●
Chapter 4.6.3.4, "Modulation Settings", on page 273
4.5.1.5 Supported Coding Schemes
Coding is a technique used to improve the signal properties and signal reception and is
required only when using some types of modulation. In general, the coding schemes
are applied before modulation. The modulation symbols are coded directly before I and
Q values or frequency shifts are assigned. The applied coding is directly related to the
selected modulation methods. This explains why coding schemes are not freely com-
binable with the modulation methods.
Refer to Chapter 4.6.5.2, "Common Coding Algorithms", on page 295 for overview on
the available coding combinations. This section also defines the modulation types for
which the various coding procedures can be used.
Related settings:
●
"Coding" on page 267
4.5.1.6 Supported Baseband Filters
In the wireless transmission technique, filters are applied to shape the baseband signal
before it is modulated on the RF. The selected baseband filter type and shape affect
the output stream, especially while generating broadband signals. If the filter is too nar-
row, it cuts the signal. If the filter is too wide, the signal could be distorted by some
unwanted signals.
To fulfill wide range of requirements, the R&S SMW offers a wide selection of prede-
fined baseband filters. The predefined filters are designed for the special spectrum
characteristics of the different communication standards. However, depending on the
selected filter form one or more filter parameters are provided for even more precise
adjustment of the filter characteristic. You can select for example more steeper edges
or change the transition bandwidth. For more information on the provided settings,
refer to "Impact of the Filter Parameters" on page 249.
The selection of user-defined filter offers even more flexibility. The later is a useful
interface while filters with complex or proprietary form are required. For more informa-
tion, refer to "User filter" on page 249.
Common Functions and Settings in the Baseband Domain
To Next Page
Loading...
