R&S SMB Command Description
1407.0806.32 6.33 E-2
SOURce:FM Subsystem
The FM subsystem contains the commands for checking the frequency modulation. The FM-specific
characteristics of the internal modulation source are defined with commands SOURce:FM:INTernal:...
Characteristics which are valid for all modulations and the LF Output are configured in the
SOURce:LFOutput subsystem (e.g. frequency). The external signal is input at the MOD EXT
connector. Internal and external modulation source can be selected at the same time, thus enabling
two-tone FM modulation.
The keyword SOURce is optional with commands and can be omitted.
Command Parameters Default unit Remark
[SOURce:]FM[:DEViation] <numeric_value> Hz
[SOURce:]FM:EXTernal:COUPling AC | DC
[SOURce:]FM:EXTernal:DEViation 0 Hz…40 MHz Hz
[SOURce:]FM:MODE NORMal | LNOise | HDEViation
[SOURce:]FM:SENSitivity? 0 Hz…40 MHz Hz Query only
[SOURce:]FM:SOURce EXT | INT | INT, EXT
[SOURce:]FM:STATe ON | OFF
[SOURce:]FM[:DEViation] 0 Hz ... 20 MHz
The command sets the modulation deviation of the frequency modulation in Hz. The maximal
deviation depends on the RF frequency set and the selected modulation mode (see data sheet).
Example:
FM 5E3
'sets the FM modulation deviation to 5 kHz.
*RST value Resolution Options SCPI
10 kHz See data sheet Compliant
[SOURce:]FM:EXTernal:COUPling AC | DC
The command selects the coupling modefor the external modulation input (MOD EXT) in the case of
frequency modulation.
Note:
Coupling for external feed via input MOD EXT can be set independently for all modulations.
Parameters: AC
The DC voltage component is disconnected from the modulation signal.
DC
The modulation signal is not changed.
Example:
FM:EXT:COUP AC
'selects the coupling mode AC for external frequency modulation.
*RST value Resolution Options SCPI
AC - Compliant
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