Instrument Function
R&S
®
SMBV100A
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Operating Manual 1407.6062.32 ─ 08
The symbol rate set must not deviate from the symbol rate of the external signal by more
than 2% (see also data sheet).
5.8.2.4
Synchronous Signal Generation
Different simulation schemes such as MIMO for instance require the generation of two
or more very precise synchronized signals in the baseband and the RF domain.
Two or more instruments are denoted as “perfectly synchronized” if the following criteria
are fulfilled:
●
The frequency and the phase of the RF carriers are equal.
●
The RF levels are equal
●
The modulation signals have equal timing, i.e. the symbol rate and the signal gener-
ation start determined by the triggering are equal. The contents of the signal, how-
ever, may be different, as it is for instance in a MIMO system.
In the R&S SMBV, the first two requirements are fulfilled by adjusting the parameters
"Baseband Phase Offset" and "RF Level". A special synchronization mode is provided to
meet the third requirement, i.e. to enable several R&S SMBV to generate a simultaneous
and synchronous signal.
Synchronization mode is an instrument's configuration in which one of the instruments is
used as a master and the other(s) are slave(s). The master instrument supplies the slave
instrument(s) with its system and reference clock as well as with its trigger signal. The
instruments have to be configured and connected as described in the following sections.
This straightforward method ensure the simultaneous and synchronous signal generation
in both the baseband and the RF part. However, to ensure even better phase coherence
of the signal at the RF outputs, the LO Coupling feature of the R&S SMBV should be
used. For more information about this feature, see
chapter 5.4.5, "Local Oscillator - LO
In the R&S Signal Generator, the parameters required to achieve a “perfectly synchron-
ized” state have to be gathered only once; they are stable in the time are not influenced
by turning the instrument on and off. Refer to Application Note 1GP67 for detailed infor-
mation on how to adjust the required settings.
Connecting Several R&S SMBVs for Precise Synchronous Signal Generation
For working in master-slave synchronous mode, connect the instruments as follow:
1. Connect the instruments as a daisy chain, i.e. connect the inputs of each further
instrument to the outputs of the previous one.
2. Connect the output CLK OUT of the master instrument to the signal input CLK IN of
the slave one.
Note:
From firmware version 2.05.269 on, the trigger information is modulated on the
clock signal and no additional cabling is necessary. For older firmware versions how-
ever, a connection between the output MARKER 1 of the master instrument and the
signal input TRIG of the slave one is required.
Baseband Signal - Baseband Block
Summary of Contents for SMBV100A
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