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Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide 105
Preliminary Optimizing Performance
Preliminary Using Unleveled Operating Modes
Using Unleveled Operating Modes
Figure 5-20 Power Search and ALC Off Softkeys
ALC Off Mode
Turning ALC off deactivates the signal generator’s automatic leveling circuitry, enabling you to
measure the output at a specific point in a test setup and adjust as required for the desired power
level at that point. Turning ALC off is useful when the modulation consists of very narrow pulses
that are below the pulse width specification of the ALC or when the modulation consists of slow
amplitude variations that the automatic leveling would remove.
1. Preset the signal generator.
2. Set the desired frequency.
3. Set the desired amplitude.
4. Connect the power meter to the point at which you want a specific power level.
5. Turn the RF output on.
6. Deactivate the signal generator’s automatic leveling control: Press AMPTD > ALC Off On to
highlight Off.
Available only when
ALC = Off
Available only when
Power Search Reference =
Available only when
Power Search = Span
Auto: The calibration routine executes whenever
output frequency or amplitude changes.
Span: Pressing Do Power Search executes the
power search calibration routine once over a
selected frequency range.
The corrections are stored and used whenever you
tune the signal generator to within the calibrated
frequency range.
For details on each key, use key help
as described on see page 42.
RMS: Value is a DC
bias equivalent to the
value derived from the
file header or the
calculated value from
the current I/Q data.
Fixed: Uses a fixed 0.5
Vrms value (Same
value is used with Ext
I/Q data).
Manual: Allows user to
specify the DC bias
voltage value (0–14
Vrms).
Modulated: Uses the
AC bias from the actual
modulating signal.
Manual
User: Enables the
user to set the
signal generator
frequency settings.
Full: The signal
generator selects
its full frequency
range for the power
search.
Only available when
I/Q is on and I/Q
Source is set to
External.
These
softkeys are
only active
when an ARB
waveforms is
playing in
memory.
Manual: User must explicitly execute a power
search to calibrate the open loop ALC level.
Note:
1) This feature is not available on N5183A.
2) This feature is only available in instruments
beginning with serial number 4818 or greater or
and with Option 099.