Configuring the Internal Baseband Source
R&S
®
SMW200A
228User Manual 1175.6632.02 ─ 16
For the generation of modulation signals, the instrument uses the following input sig-
nals:
●
Internal Modulation Data
●
"External Modulation Data" on page 229
●
Clock Signals
●
Control Signals
Signal sources
The data, the clock and the trigger signals can be both internally generated and sup-
plied from an external source. Control signals however are always generated internally.
Depending on the current configuration, the internally generated data and marker sig-
nals are output on one or several connectors. For a detailed description of the output
capabilities of the instrument and of how to configure the required connectors, see
Chapter 11.2, "Configuring the Local and Global Connectors", on page 661.
Internal Modulation Data
The R&S SMW uses the following internal modulation data sources:
●
Data lists
Data lists are externally or internally created binary lists with modulation data.
The instrument provides standard file select function for loading of existing data
lists, creating internally new data lists or editing an existing one. Internally, data
lists are created in the dedicated "Data List" editor (see Chapter 4.6.3.7, "Data List
Editor", on page 280). A separate file is created for each list and stored on the
instrument's hard disk. The filename is user-defined; the file extension is
*.dm_iqd.
The maximum length of a data list is determined by the size of the data list memory
(see data sheet). There is no restriction on the number of lists that can be stored.
Settings for file handling, like transferring external data lists to the instrument, or
renaming of folders and files, are accessed via the standard "File Manger" function.
(See also Chapter 10, "File and Data Management", on page 619).
●
Data patterns
Simple data patterns such as binary 0 ("All 0") strings or 1 ("All 1") strings or vari-
able bit strings with a maximum length of 64 bits can be used as internal modula-
tion data.
●
PRBS data
The PRBS generators deliver pseudo-random binary sequences of differing length
and duration. They are known as maximum length sequences. PRBS sequences
are generated with the aid of ring shift registers with feedback points determined by
the polynomial.
The pseudo-random sequence from a PRBS generator is uniquely defined by the
register number and the feedback. The Table 4-2 describes the available PRBS
generators.
For PRBS15 and PRBS23, a CCITT V.52-compliant data inversion is performed in
the feedback path automatically.
Common Functions and Settings in the Baseband Domain
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