Instrument Function
R&S
®
SMU200A
241Operating Manual 1007.9845.32 ─ 15
FM External Coupling
(Source External only)
Selects the coupling mode (AC or DC) for external feed.
Note: Coupling for external feed via input EXT MOD can be set independently for mod-
ulations AM, FM and PhiM.
"AC"
The d.c. voltage content is separated from the modulation signal.
"DC"
The modulation signal is not altered.
SCPI command:
[:SOURce<hw>]:FM:EXTernal:COUPling on page 708
External Input Impendance
(Source External only)
Selects the impedance for external feed via the EXT MOD input.
Selection 50 Ohm and high (>100 kOhm) is available.
Note: This setting affects all analog modulations which use the external modulation
source.
SCPI command:
[:SOURce<hw>]:INPut:MODext:IMPedance on page 721
5.5.11.5 Phase Modulation (PhiM)
Phase modulation (PhiM) requires option R&S SMU-B20 (FM/PhiM Modulator) or R&S
SMU-B22 (FM/PhiM Modulator and Low Phase Noise). These options are available for
Path A only.
It is not possible to use phase modulation simultaneously with frequency modulation.
An internal and/or external source can be selected for phase modulation. The LF GEN
modulation generator is available as the internal source.
The EXT MOD input connector for external feed of analog modulation signals is at the
rear of the instrument. The coupling mode of the input (AC or DC) and the impedance
can be selected.
Selection between the following modulation modes is possible:
●
"High Bandwidth" mode with full setting range for modulation bandwidth and limited
PhiM deviation.
●
"Low Noise" mode with better signal/noise ratio, but reduced setting range for mod-
ulation bandwidth and deviation (see data sheet)
●
"High Deviation" mode with full setting range for PhiM deviation and a reduced setting
range for modulation bandwidth. Phase noise is reduced in the lower modulation
frequency range compared to the default mode.
RF Signal and Analog Modulations - RF Block
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