Instrument Function
R&S
®
SMF100A
154
Operating Manual 1167.2319.02 ─ 12
Figure 5-1: SSB Phase Noise, comparison of the main synthesizer PLL bandwidth "Narrow" and
"Normal"
The phase noise performance for frequency offsets higher than 100
kHz is improved in
the narrow PLL bandwidth mode (blue measurement curve). In the offset range 10
kHz
to 100
kHz, the pedestal phase noise deteriorates.
Interactions of the Frequency and Phase Modulation Modes and the Configura-
ble Main PLL Bandwidth
If you generate a frequency- or phase-modulated RF signal, you can also set the nar-
row PLL bandwidth, provided you perform the modulation in "Low Noise" mode. Con-
sequently, some operation modes exclude each other.
The table shows the operating modes which can be activated simultaneously (+) or
which deactivate each other (-):
Main PLL
Bandwidth
FM Mode
"Normal"
FM Mode
"Low Noise"
ɸ
M Mode
"Low Noise"
ɸ
M Mode
"High Bandwidth"
ɸ
M Mode
"High Deviation"
Normal
+
+
+
+
+
Narrow
-
+
+
-
-
Behavior of the instrument when you change the frequency or modulation
modes
When you enable a mode, while another excluding mode is already active, the
R&S
SMF automatically adjusts the parameters of this previously set mode. Conse-
quently, the instrument always performs the signal generation with the current settings
and adjusts the foregoing settings accordingly, if required.
RF Frequency Block
