Configuring the RF signal
R&S
®
SMM100A
389
User Manual 1179.1341.02 ─ 05
"Fixed"
Fixes the attenuator and amplifier paths for the current RF level and
provides signal output with constant output VSWR. The resulting level
range is indicated under
This mode is coupled with ALC, and therefore only effective when
ALC is enabled.
"Manual"
Allows you to set the
The user-specified nominal attenuation is useful for instruments
equipped with a mechanical step attenuator.
Similar to "Fixed" mode, relays and amplifier stages keep the speci-
fied value, providing interruption-free signal output level.
Remote command:
Attenuation
Sets the nominal attenuation of the RF signal in
Remote command:
[:SOURce<hw>]:POWer:ATTenuation
Level Range
Shows the interruption-free range of the level that you can use in the selected mode.
Remote command:
:OUTPut<hw>:AFIXed:RANGe:LOWer?
:OUTPut<hw>:AFIXed:RANGe:UPPer?
RF OFF Mode
Determines the state of the step attenuator, when the RF signal is switched off.
The setting is not affected by an instrument preset ([Preset] key or
*RST
) and the
"Save/Recall" function. It is reset only by factory preset.
"Unchanged"
Freezes the setting of the step attenuator.
Use this mode if a constant VSWR (Voltage Standing Wave Ratio) is
required.
"Full Attenuation"
Switches to the maximum attenuation.
Use this mode for applications that require a high level of noise sup-
pression.
Note:
"Full Attenuation" has higher priority than the RF level modes
.
Remote command:
[:SOURce<hw>]:POWer:ATTenuation:RFOFf:MODE
7.12.1.2
Reverse power protection
The R&S
SMM100A is equipped with a reverse power protection circuit.
The reverse power protection is tripped when the power of signals reflected from the
load or external signals applied to the RF output get too high. A relay opens and inter-
Improving level performance