Rohde & Schwarz SMM100A, User Manual

Page: 451 / 1088

Multi-instrument setups
R&S
®
SMM100A
451 User Manual 1179.1341.02 ─ 05
9.3.4.2 Overview of the baseband and RF output signals
Usually, the generated baseband signal is modulated on the RF frequency and output
at the RF connector. As shown in
Table 9-2 , the R&S SMM100A outputs the digitally
modulated signal converted to an analog I/Q baseband output signal. The analog
baseband signal can be output single ended or differential (non-inverted); an RF enve-
lope signal can be generated, too.
The Table 9-2 shows the possible output connectors with the corresponding kind of sig-
nal.
Table 9-2: Physical output signals
Type Output Signal Output connector GUI element Refer to
RF RF signal RF "RF" Chapter 7, "Configuring the RF signal" ,
on page 294
BB Analog signal
●
Single ended
●
Differential
●
RF Envelope
●
I/Q
●
I/Q Bar
●
I/I Bar
"I/Q Analog" Chapter 9.6, "I/Q analog output settings" ,
on page 476
9.3.4.3 Interdependencies
The following functions cannot be activated simultaneously. They deactivate each
other .
●
The internal baseband generator ("Baseband" block) and the external digital base-
band input ("BB Input")
●
The output of analog ("I/Q Analog") and digital ("I/Q Digital") signals
9.3.4.4 Important signal parameters and interface's characteristics
Correct signal processing of the externally supplied input signals in the instrument and
correct processing of the output signal in the next connected instrument require infor-
mation of signal parameters. These signal parameters are sampling rate, crest factor
and signal level, expressed as peak or as RMS level value.
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 9-2 ).
The R&S SMM100A uses the crest factor to calculate the power levels, that is the
instrument compensates the RMS levels of the externally supplied signal by the crest
Control and operation of external instruments