Configuring the Signal in the RF Domain
R&S
®
SMW200A
442User Manual 1175.6632.02 ─ 16
Figure 7-2: Synchronizing a subsequent instrument using the internal 10 MHz reference signal of
the R&S
SMW
The internal reference oscillator supplies the reference frequency.
In addition, you can shift the frequency by an external tuning voltage within a cer-
tain range, EFC (External Frequency Control). This function is used, for example,
in phase noise measurement systems.
The frequency shift resulting from a tuning voltage value depends on the technical
equipment of the instrument. See the data sheet for the associated technical data
like sensitivity, input voltage range and impedance. The maximum bandwidth for
external tuning signal input is approximately 50 Hz.
Note: The bandwidth of an external PLL (Phase Locked Loop) used in a phase
noise measurement system, must be less than the bandwidth of the external tuning
signal input. If the measurement requires a higher bandwidth for the PLL, we rec-
ommend that you use the external FM modulation (DC coupling) in low noise
mode. The FM-DC mode yields a fixed tuning sensitivity that is independent of the
RF output frequency and corresponds to the set FM deviation.
Settings:
– Source: "Internal"
●
External f
ref
= 10 MHz input at REF IN (10 MHz output at REF OUT)
If you have a clean external reference signal with 10 MHz frequency, you can
directly pass it to the output. The signal quality remains the same.
Figure 7-3: Synchronizing instruments with an externally applied 10 MHz reference signal
Settings:
– Source: "External"
– External Reference Frequency: "10 MHz"
Set the additionally provided parameters, as for example the synchronization band-
width according to the requirements of the application.
●
External f
ref
= 1 to 100 MHz input at REF IN (10 MHz output at REF OUT)
Reference Oscillator
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