User`s guide

4-158 Agilent E6432A Microwave Synthesizer User’s Guide
HPE6432_SetAlcBandwidth
ViStatus HPE6432_SetAlcBandwidth (ViSession
instrumentHandle, ViBoolean alcBandwidth);
Purpose
This function sets the ALC bandwidth to either high or low while all
other instrument state settings are unaffected; this setting affects the
current state as well as the list.
• When high ALC bandwidth is selected, the ALC loop has a
bandwidth of 100 kHz.
• When low ALC bandwidth is selected, the ALC loop has a bandwidth
of 10 kHz.
Internal Leveling Mode
When using Internal Leveling Mode and frequencies less than
560 MHz, the ALC bandwidth is always low. When the frequency is
greater than or equal to 560 MHz, the ALC bandwidth is always high.
External Leveling Mode
When using External Leveling Mode, the ALC bandwidth is low for all
frequencies by default, but can be changed to high if desired.
In External Leveling Mode, high ALC bandwidth can be used in a effort
to minimize the effects of settling time. Because some situations that
use External Leveling Mode utilize an external detector, miscellaneous
equipment (such as amplifiers), and long cabling, an excessive phase
shift can be created which in turn could result in oscillations. Problems
such as this can be eliminated in External Leveling Mode by selecting
low ALC bandwidth.
The following table shows the default and selectable ALC bandwidth in
relation to leveling mode and frequency.
Leveling Mode < 560 MHz >/= 560 MHz
Internal Always
Low ALC Bandwidth
(10 kHz)
Always
High ALC Bandwidth
(100 kHz)
External Default
Low
ALC Bandwidth(10 kHz),
but Selectable to High
(100 kHz)
Default
Low
ALC Bandwidth(10 kHz)
,
but Selectable to High
(100 kHz)