Rohde & Schwarz SMF-B1, Operating Manual

Page: 209 / 653

Instrument Function
R&S
®
SMF100A
194 Operating Manual 1167.2319.02 ─ 12
"Off (Sample & Hold)"
Deactivates internal level control.
Sample & hold closes the level control loop at every frequency and
level change for a short period of time. The level control voltage is
sampled and then clamped.
Remote command:
[:SOURce<hw>]:POWer:ALC[:STATe]
on page 524
RF During Power Search - ALC
Activates the mode for the mechanical step attenuator and for output during ALC
power search.
"Normal" The RF output is active during power search.
"Minimum" The RF output is inactive during power search.
Remote command:
:OUTPut<hw>:ALC:SEARch:MODE
on page 383
Search Once - ALC
Forces the generator to execute level adjustment once, although the "Sample & Hold"
mode is active.
Remote command:
[:SOURce<hw>]:POWer:ALC:SONCe
on page 524
5.4.5.2 External Level Control
With external level control, the level control is performed using an external DC signal
applied at the EXT ALC input. The signal can be provided either by a diode detector or
a power meter. A reference voltage has to be entered for the desired level at the RF
output of the generator.
The "External Level Control" dialog is part of the Level... dialog and is opened in the
LEVEL CONTROL function block or using the "MENU" key under "Level Control".
Source - External Level Control
Selects the source for level control.
"Internal" The internal detector is used. The settings under ALC are valid (see
Chapter 5.4.5, "Automatic Level Control - ALC" , on page 192).
"Diode" A diode detector is connected to the EXT ALC input. The RF level is
controlled by the external voltage provided by the detector. The refer-
ence voltage for the desired level at the RF output of the generator
has to be entered below. See the specification of the detector for
details.
RF Level