Rohde & Schwarz SMBV100B, User Manual

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Multi-Instrument Setups
R&S
®
SMBV100B
428 User Manual 1178.4460.02 ─ 03
8.3 Generating Time-Aligned Baseband 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.
One possible way to achieve quasi-simultaneous signal start is to trigger the instru-
ments by the same trigger event, for example from a
common trigger source .
Because of the trigger signal propagation time and the signal processing time, how-
ever, this method does not achieve precise time aligned signals.
To generated synchronous and time aligned signals with multiple instruments, use
the master-slave mode .
This section explains how to use the provided settings to define the signal generation
start in the basebands of
multiple instruments .
● Connecting Multiple Instruments in Master-Slave Mode .......................................428
● Triggering Several Instruments with a Common Trigger Signal ............................434
8.3.1 Connecting Multiple Instruments in Master-Slave Mode
About the master-slave mode
When connected in master-slave mode, two or more R&S SMBV100B or one
R&S SMBV100B and several other signal generators such as R&S SGT or R&S SMBV
can generate synchronous and time aligned signals.
In this mode, the master instrument generates and outputs a dedicated synchroniza-
tion signal (Sync Out), that has to be fed into the slave instrument. The slave instru-
ment detects and demodulates the signal, and retrieves both the baseband clock and
the trigger signal from it. Slave instruments can forward the received synchronization
signal (Sync In) and output it to trigger further slaves.
Synchronization signal
The synchronization signal is a 50 MHz signal that carries the trigger pulse modulated
on it. Hence, it provides
joint triggering and baseband clock synchronization at the
same time.
Final time alignment can require adding I/Q or trigger delay. However, once synchroni-
zation is achieved, the master-slave mode ensures reproducibility of triggering, if the
used waveform, sample rate and cabling are not changed.
Test setup
Regarding the synchronization signal , the instruments can be connected (cascaded)
in a star configuration (see Figure 8-2 ) or in a daisy chain (see Figure 8-1 ).
Generating Time-Aligned Baseband Signals