Agilent Technologies 83620B User Manual

4
ALC
5
Note
Two terms are used in the following discussions: p ower output and
ALC level. Power output means actual output p ower including the
eects of the attenuator. ALC level means power levels b efore the
attenuator. In swept signal generators without attenuators, these two
terms are equivalent.
Internal Leveling -
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Leveling Mode Normal ,
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Leveling Point Intrnl
In this conguration ( Figure A-1), power is sensed by a detector
internal to the swept signal generator and a dc output from this
detector is fed back to the Level Control Circuits .
The ALC level is limited at the low end by the Level Control Circuits
and at the high end by maximum available p ower. Noise and drift
limit the range at the low end to 0 20 dBm or greater.
The combination of RF frequency and RF components (dierent
mo dels of swept signal generator have dierent RF components)
limit the ALC range available at the high end. The internal
instructions (rmware) of the swept signal generator limit the ALC
level range available for request from 0 20 to +25 dBm. If the
power level requested is higher than the swept signal generator is
capable of pro ducing, the maximum available p ower is pro duced,
and the message line displays UNLVLED (unleveled). When the swept
signal generator p erforms frequency sweeps at certain ALC levels,
maximum available p ower can be exceeded during small p ortions of
the sweep; in this case, a ashing UNLVLED message app ears.
ALC leveling accuracy depends on power level. Although the ALC
level is useable from 0 20 to +25 dBm, it is most accurate from
0 10 to +10 dBm. This fact is reected in the performance
specications of the swept signal generator.
Coupled Operation. Since many applications require power output
less than 0 20 dBm, an optional step attenuator has a range of
0 to 90 dB , in 10 dB steps. With this option, power output down
to 0 110 dBm is achieved when the Step Attenuator and Level
Control Circuits work in conjunction (see Figure A-1). With the
attenuator, the ALC level is normally used over the smaller, more
accurate p ortion of its range. Since ALC lev
el accuracy suers b elow
0 10 dBm, and at some frequencies only +1 dBm of RF output is
available, the ALC level is set between 0 10 and 0 dBm. For p ower
less than 0 100 dBm, the attenuator is set to 90 dB, and the ALC
level is used from 0 10 to 0 20 dBm. At frequencies where power
output ab ove 0 dBm is desired, the attenuator is set to 0 dB, and the
ALC level is used from 0 to +25 dBm (or whatever p ower is available
at the RF frequency in use).
Coupled op eration is assumed by the swept signal generator unless
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Uncoupl Atten or
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Leveling Mode ALCoff is selected. The proper
combination of ALC level and attenuator setting is decided by the
A-6 Operating and Programming Reference

Agilent Technologies 83620B Specifications

General

Brand	Agilent Technologies
Model	83620B
Category	Inverter
Language	English