R&S SMJ100A, Operating Manual

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Instrument Function
R&S
®
SMJ100A
313 Operating Manual 1403.7458.32 ─ 14
5.8 Baseband Signal - Baseband Block
The R&S SMJ provides you with the ability to generate digital modulation signals in
accordance with the definitions in the digital standards or with user-definable charac-
teristics. Signals are generated in realtime or from a data store with the aid of external
and internal data. You can also load externally computed modulation signals into the
R&S
SMJ in the form of waveform files.
Several digital standards are provided, plus digital modulation with user-definable sig-
nal characteristics, generation of waveforms with the aid of the Arbitrary Waveform
Generator and generation of multi carrier CW signals with the aid of Multi Carrier CW.
The settings for digital modulation can be accessed in the block diagram via the "Base-
band" function block or with the aid of the MENU key.
The equipment layout for generating the internal, digital modulation signals includes
the options Baseband Main Module (B13) and one of the options Baseband Generator
(B9/B10/B11) .The three Baseband Generator options feature different ARB memory
sizes (see data sheet). Apart from the memory size, however, the options offer the
same functionality, either one can be installed.
In addition, the appropriate option is required for the digital standards. These options
are specified in the description of the respective standard.
In the subsequent signal route the baseband signals can be frequency-shifted, detuned
or loaded with noise (see
Chapter 5.7, "Impairment of Digital I/Q Signal and Noise
Generator - AWGN/IMP Block" , on page 288).
5.8.1 Data and Signal Sources in Baseband
This section describes the common characteristics of the signals used for generating
the baseband signal for all standards, including for example all listed data sources. The
selection in the digital menus at any given time depends on the parameter and stan-
dard concerned and is clear from the selection list offered in the dialog. The external
data sources may therefore not be available in certain cases.
Characteristics which are uniquely specific to particular standards are described in the
corresponding manual.
The following input signals are used when digital modulation signals are being gener-
ated:
●
Modulation data
●
Clock signals
Baseband Signal - Baseband Block