User`s guide

Agilent E6432A Microwave Synthesizer User’s Guide 3-29

Soft Front Panel Help

ALC System Diagram

Power Search

Power Search, available from the Soft Front Panel, returns an ALC

integrator offset value for the current frequency and ALC power that is

selected on the main Soft Front Panel (attenuation is not counted). If

the List Dialog Box is open, a Power Search is performed on each item

in the list that has a P flag selected.

Power Search ALC integrator values ARE NOT USED (have no effect)

when leveling is on:

The ALC integrator offset value that is returned from a Power Search is

not used (has no effect) when leveling is turned on (ALC loop is closed).

Power Search ALC integrator values ARE USED (improve power

accuracy) when leveling is off:

This ALC integrator offset value minimizes the power level change that

occurs when leveling is turned off (ALC loop is open). Leveling is

typically turned off for pulsed signals with pulse width less than 2.5 us

and for complex modulated signals such as I/Q modulation.

As an example, Power Search could be used to correct (offset) the power

level of a signal with leveling turned off as follows: If the frequency is

set to 10 GHz, output power is set to –10 dBm, and leveling is turned off

(ALC loop is open), the power error may be greater than desired. The

greater power error is caused because leveling is turned off. If a Power

Search is performed, leveling is momentarily turned on (ALC loop is

momentarily closed) so that the power is as accurate as possible and the

integrator offset is adjusted to zero using an offset zero DAC. Leveling

is then turned off (ALC loop is opened) and because the integrator error

voltage is zero, the power level does not change.

For complete specifications, refer to “Specifications and

Characteristics” on page 6-1.