Configuring the RF Signal
R&S
®
SMW200A
488User Manual 1175.6632.02 ─ 30
Known restrictions
If you cascade instruments or channels at frequencies below 200 MHz, that is in cou-
pled or external mode, make sure that:
●
All channels are equipped equally regarding option R&S SMW-B22, that means
each channel is equipped with or without the option.
●
The connection between the REF OUT of the first instrument and REF IN of the
subsequent instrument is established, see Chapter 8.5, "Reference Oscillator",
on page 473.
Frequencies below 200 MHz are generated using downconversion. Therefore the
coherence of the cascaded channels in this frequency range is not as good as at
higher frequencies.
The first test setup example represents all variants of the coupling modes, and
describes step-by-step how to configure each of the Rohde & Schwarz signal genera-
tors. The following examples show further conceivable test setups. To configure these
test setups, proceed similarly as shown in the first example.
Example: Cascading three Rohde & Schwarz Signal Generators
Figure 8-5: Set up of LO coupling with three Rohde
&
Schwarz Signal Generators
Generator 1 = "Internal"; "LO OUT > Off"
Generator 2 = "A External & A->B Coupled"; "LO OUT > On"
Generator 3 = "External"; "LO OUT > Off"
A frequency of 5 GHz is assumed.
●
Signal Generator 1 is a one-path instrument, for example R&S SMW and uses its
internal oscillator signal.
●
Signal Generator 2 is a two-paths instrument, for example a R&S SMW200A. It
receives the LO signal from the first instrument and assigns it to both paths.
●
Signal Generator 3 is a one-path instrument, for example R&S SMW,
R&S SGT100A, or R&S SMBV100A. It receives the LO signal from the second
instrument.
To configure the application, proceed as follows:
1. Connect the first signal generator REF OUT with LO IN of the second instrument,
and similarly the LO OUT of the second signal generator with LO IN of the third.
2. Configure Signal Generator 1.
Select "Freq = 5 GHz".
Local Oscillator Coupling
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