Configuring the internal baseband source
R&S
®
SMM100A
102
User Manual 1179.1341.02 ─ 05
Step 2: Enable the following settings:
●
"ARB > Trigger In > External Delay Unit > Time"
●
"ARB > Trigger In > Specified External Delay = 10 us"
Logically, the "Actual External Delay" changes to 10 us.
Step 3:
●
Switch to "ARB > Trigger In > External Delay Unit > Samples".
The value of "ARB > Trigger In > External Delay" is 10 samples.
Receiving and providing trigger signals
In test setups that combine the signal of two or more instruments it is often required
that:
●
The signal generation starts at a defined moment
●
The signal generation starts simultaneously (or with an exactly defined delay) in all
involved instruments.
For information on
simultaneous signal generation start in multiple instruments
,
Chapter 9.2, "Generating time-aligned baseband signals"
4.4.1.4
Supported modulation signals
The R&S
SMM100A supports a range of predefined digital and analog modulation sig-
nals. This section focuses on the possibility to digitally modulate the baseband signal.
In communication techniques, commonly used digital modulation schemes are based
on keying. From the several existing keying techniques, this instrument supports ASK
(amplitude shift keying), FSK (frequency shift keying), PSK (phase shift keying), and
QAM (quadrature amplitude modulation).
The digital modulation procedure is described by mapping. That is, by the assignment
of I and Q values (PSK and QAM) or frequency shifts (FSK) to every modulation sym-
bol. The resulting modulated signal is graphically represented by a constellation dia-
gram, in that each possible symbol is represented by a discrete point on a complex
plane. The number of used bits per symbol is a modulation parameter. The exact posi-
tion of the symbols on the constellation diagram is determined by the used coding
scheme. You can also change the symbol position by applying rotation.
Most of the provided modulation schemes are implemented according to a communica-
tion standard. The QAM procedures 16QAM, 32QAM, 64QAM, for instance, have been
produced in accordance with ETSI standard ETS 300429 for digital video broadcasting
Common functions and settings in the baseband domain
