R&S SMJ100A, Operating Manual

Page: 225 / 874

Instrument Function
R&S
®
SMJ100A
209 Operating Manual 1403.7458.32 ─ 14
Remote command:
[:SOURce<hw>]:FREQuency:PHASe:CONTinuous:STATe
on page 717
5.5.4 Reference Oscillator
The R&S SMJ is equipped with an internal reference oscillator that generates a refer-
ence frequency of 10 MHz. It is used as internal reference source for the synthesizer
and the local oscillator. Alternatively, you can apply an external reference signal.
Regardless of the used reference source (internal or external), the R&S SMJ 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 5-9: Synchronizing a subsequent instrument using the internal 10 MHz reference signal of
the R&S SMJ
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:
–
Source : "Internal"
●
External f
ref
= 10 MHz (10 MHz REF OUT)
RF Signal and Analog Modulations - RF Block