Signal Routing and System Configuration
R&S
®
SMW200A
120User Manual 1175.6632.02 ─ 30
Sample rate
The sample rate of the digital input and output signal can be defined manually or auto-
matically retrieved from the input and estimated for the output signal. The bandwidth
and thus the sample rate of the digital input signal is not limited by the installed sample
rate options.
For more information, see data sheet.
Crest factor
According to its definition, the crest factor gives the difference in level between the
peak level and RMS level value in dB (see Figure 4-5).
The R&S SMW uses the crest factor to calculate the power levels, that is the instru-
ment compensates the RMS levels of the externally supplied signal by the crest factor.
For example, the crest factor of the external signal is important for the calculation of
the RF output power.
Figure 4-5: Relation between the level settings
Test setups often involve an up-converter connected to the I/Q connectors of the gen-
erator or feeding of external signal to the digital input of the R&S SMW. As a rule,
whenever an I/Q signal is transferred between two instruments, the crest factor and the
peak levels of the two involved instruments have to be coordinated. Proper signal set-
tings and correct results are ensured if the peak level and crest factor values at the I/Q
outputs of the "source" instrument (e.g. the R&S SMW) and the I/Q inputs of the up-
converter are equal.
In the R&S SMW, level values are represented as relative to a full scale (see Fig-
ure 4-5).
Where to find the necessary values
●
Dialog "BB Input"
See Chapter 4.6, "Digital Baseband Input Settings", on page 158
●
Dialog "Digital I/Q Out"
See Chapter 4.7, "I/Q Digital Output Settings", on page 172
●
Dialog "Analog I/Q Out"
See Chapter 4.8, "I/Q Analog Output Settings", on page 182
●
Dialog "Setup > System > Baseband Powers", see Chapter 9.2, "Querying Informa-
tion on the Baseband Power Levels", on page 621
●
Dialog "Fading > Insertion Loss Config / Coupled Parmeters > Insertion Loss"
See user manual R&S
®
SMW-B14/-K71/-K72/-K73/-K74/-K75/-K820/-K821/-K822/-
K823 Fading Simulation.
Overview of the Input and Output Signals and Interfaces
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