Instrument Function
R&S
®
SMB100A
172Operating Manual 1407.0806.32 ─ 13
The modulation depth entered under "AM Depth" is reached with 1 volt modulation of the
input.
Remote command:
[:SOURce<hw>]:AM:SENSitivity? on page 290
AM External Coupling
(Source External only)
Selects the coupling mode (AC or DC) for external feed.
Note: Coupling for external feed via input MOD EXT is set for all modulations with external
source.
Remote command:
[:SOURce<hw>]:AM:EXTernal:COUPling on page 289
External Input Impendance
(Source External only)
Selects the impedance for external feed via the EXT MOD input.
Selection 600 Ohm and high (>100 kOhm) is available.
Note: This setting affects all analog modulations which use the external modulation
source.
Remote command:
[:SOURce<hw>]:INPut:MODext:IMPedance on page 310
5.4.3 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 input connectors for external feed of analog modulation signals are at the
front 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 setting
range for modulation bandwidth (see data sheet).
It is not possible to use frequency modulation simultaneously with phase modulation.
Modulation
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