Instrument Function
R&S
®
SMB100A
128Operating Manual 1407.0806.32 ─ 13
Power-On State - RF Signal
Selects the state which the RF output is to assume after the instrument is switched on.
"RF Off"
The output is deactivated when the instrument is switched on.
"Previous Set-
ting"
When the instrument is switched on, the output assumes the same state
as it had when the instrument was switched off.
Remote command:
:OUTPut<hw>[:STATe]:PON on page 278
Display Level as Voltage of EMF - RF Level
Activates display of the signal level as voltage of the EMF (no-load voltage). If this setting
is deactivated, the level is displayed as a voltage over a 50 Ohm load.
Remote command:
n.a.
5.3.5.4 Automatic Level Control - ALC
Your signal generator is equipped with an automatic level control unit to obtain best RF
level accuracy.
Automatic Level Control (ALC) is an adaptive control system to stabilize the RF output
level. It continuously monitors the current level and adjusts it to keep a steady state over
temperature and time.
ALC is active in almost all applications by default. However, the Pulse Modulation mode
excludes ALC, as the control loop would detect incorrect values and result in level devi-
ations.
Also note that ALC may detect incorrect values in multi-transmitter test setups. If mul-
tiple generators are coupled, reverse power may affect the ALC readings. Based on
incorrect values, ALC would have an impact on the signal to intermodulation ratio.
ALC States
The following description basically explains the ALC states and their principle of opera-
tion. In particular ALC OFF (Sample & Hold) gives an overview on the function in terms
of the equipment of the generator.
The R&S SMB offers the ALC states:
●
AUTO
automatically adjusts the output level to the operating conditions.
●
On
enables ALC permanently, regardless of the currently selected mode.
●
Off
deactivates ALC.
The instrument switches to Sample & Hold (S&H) state, which still allows to maintain
a constant output level.
RF Block
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