Configuring the Signal in the RF Domain
R&S
®
SMW200A
455User Manual 1175.6632.02 ─ 16
Example: Cascading three Rohde & Schwarz Signal Generators
Figure 7-6: Set up of LO coupling with three Rohde
&
Schwarz Signal Generators
Generator 1 = "Internal"; "LO OUT > On"
Generator 2 = "A External & A->B Coupled"; "LO OUT > On"
Generator 3 = "External"; "LO OUT > Off"
Signal Generator 1 uses its internal oscillator signal. Signal Generator 2 receives the
LO signal from the first instrument and assigns it to both paths. Signal Generator 3
receives the LO signal from the second instrument. The frequency is assumed to be
5 GHz.
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".
a) Select "RF > Ext. Ref / LO Coupling > Mode > Internal".
b) Set "Out State > B On".
3. Configure Signal Generator 2
a) Set "Freq > 5 GHz".
b) Check if both paths are able to deal with the desired RF frequency.
Tip: You can find out the maximum frequency with the remote control com-
mand SOUR<ch>:FREQ? MAX.
● if both paths can handle the RF frequency, select "RF > Ext. Ref / LO Cou-
pling > Mode > A External & A->B Coupled"
● if path A is not sufficiently equipped, select "RF > Ext. Ref / LO Coupling >
Mode > A RF Off & B External"
● if path B is not able to handle the frequency, select "RF > Ext. Ref / LO
Coupling > Mode > A External & B RF Off"
c) Set "Out State > On".
d) If the attenuation between the interconnection "LO OUT" and "LO IN" is more
than 1 dB at the oscillator frequency, we recommend that you execute "Adjust
LO Level Current Frequency".
Note: The adjustment procedure must be completed before you perform the
adjustment on a subsequent instrument.
The signal generator automatically adjusts the internal LO signal level at the
I/Q modulator and LO OUT connector.
Local Oscillator Coupling
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