Instrument Function
R&S
®
SMF100A
156
Operating Manual 1167.2319.02 ─ 12
Regardless of the used reference source (internal or external), the R&S
SMF always
provides the configured reference frequency at the output. You can use it, for example
to synchronize several interconnected instruments.
The settings of the reference oscillator are not affected by an instrument preset ("PRE-
SET" key).
The following examples briefly explain the possible test setups and the settings to be
considered.
●
Internal f
ref
= 10 MHz (10 MHz REF OUT)
Figure 5-2: Synchronizing a subsequent instrument using the internal 10 MHz reference signal of
the R&S
SMF
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, it is rec-
ommended 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:
–
●
External f
ref
= 10 MHz (10 MHz 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.
RF Frequency Block
