R&S SMJ100A, Operating Manual

Page: 342 / 874

Instrument Function
R&S
®
SMJ100A
326 Operating Manual 1403.7458.32 ─ 14
Example:
In the following example, the marker signal is defined by an "On Time" = 1 and "Off
Time" = 2.
5.8.2 Digital Modulation - Custom Digital Modulation
The R&S SMJ can generate digital modulation signals with user-definable characteris-
tics. Baseband filtering and the symbol rate can be set within wide limits.
5.8.2.1 Overview and Required Options
The equipment layout for generating the digital modulation signals includes the options
Baseband Main Module (R&S
SMJ-B13) and Baseband Generator (R&S SMJ-B9/B10/
B11).
When modulation is ON, a two-part level indication is shown in the header section of
the display. This displays both the average power (LEVEL) and the peak envelope
power (PEP) of the modulated output signal.
The difference between PEP and LEVEL depends on the modulation type and the fil-
tering: Both values are pre-measured internally so that the displayed values match the
true values in the signal. When external signals are used, they are replaced by PRBS
data during pre-measurement.
5.8.2.2 Modulation Types - Custom Digital Mod
The available predefined modulation types are ASK (amplitude shift keying), FSK (fre-
quency shift keying), PSK (phase shift keying) and QAM (quadrature amplitude modu-
lation). Additionally, a user defined modulation mapping can be applied (see
"User
Mapping" on page 330).
The actual modulation procedure is described by mapping, which assigns I and Q val-
ues (PSK and QAM) or frequency shifts (FSK) to every modulation symbol that occurs.
This is represented graphically in the constellation diagrams.
The mapping for the selected modulation type is displayed in the "More..." submenu in
the "Modulation" menu section (see
"More - Modulation Type" on page 347).
The QAM procedures 16QAM, 32QAM, 64QAM have been produced in accordance
with ETSI standard ETS 300429 for digital video broadcasting (DVB). The QAM proce-
Baseband Signal - Baseband Block