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Instrument Function
R&S
®
SMBV100A
253
Operating Manual 1176.8016.02 ─ 17
Remote command:
[:SOURce<hw>]:AM:EXTernal:COUPling
Ext. Impedance
(Source "External" only)
Sets the impedance for the external modulation signal, applied at the EXT MOD con-
nector.
You can select 600 Ohm or high (>100 kOhm).
This setting affects all analog modulations which use the external modulation signal.
Remote command:
[:SOURce<hw>]:INPut:MODext:IMPedance
5.5.12.3
Frequency Modulation (FM)
An internal and/or external source can be selected for frequency modulation. The LF
GEN modulation generator is available as the internal source. Two-tone FM is possible
by simultaneously switching on the external and internal source.
The MOD EXT and PULSE EXT input connectors for external feed of analog modula-
tion signals are at the rear of the instrument. The coupling mode of the input (AC or
DC) can be selected.
Selection between three modulation modes is possible:
●
"Normal" mode with full setting range for modulation bandwidth and FM deviation.
●
"Low Noise" mode with better signal/noise ratio, but reduced setting range for mod-
ulation bandwidth
●
"High Deviation" mode with full setting range for FM deviation and a reduced set-
ting range for modulation bandwidth (see data sheet).
It is not possible to use frequency modulation simultaneously with phase modulation.
See
"Simultaneous Operation of Several Modulations or Other Operating Modes"
on page 250 for an overview in detail.
Frequency Modulation Settings
To access the "Frequency Modulation" dialog, select "RF/A Mod > Configure > Fre-
quency Modulation" or use the MENU key under "RF/A Mod".
In the upper section of the dialog, you can select the modulation source and activate
modulation. The modulation source can be selected independently for the different
modulation types and the LF output.
The configuration of the selected external and/or internal modulation source is per-
formed in the lower section of the menu (internal source only).
These settings affect all modulations which use the same modulation sources.
RF Block