Agilent Technologies 8360B, Руководство пользователя, Страница: 215 / 496

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Fltness Menu
Figure F-2.
User Flatness Correction T able as Display ed b y the Sw ept Signal Generator
Theory of op eration
The unparalleled lev eled output p o w er accuracy and atness of the
Agilent 8360 B-Series sw ept signal generator. This is ac hiev ed b y
using a new digital (v ersus analog) design to con trol the in ternal
automatic lev eling circuitry (ALC).
An in ternal detector samples the output p o w er to pro vide a dc
feedbac k v oltage. This v oltage is compared to a reference v oltage
whic h is prop ortional to the p o w er lev el c hosen b y the user. When
there is a discrepancy b et w een v oltages, the p o w er is increased
or decreased un til the desired output lev el is ac hiev ed. F or
comprehensiv e theory on the ALC system, refer to the 4 ALC 5 en try in
the \A" section of this man ual.
The factory-generated in ternal calibration data of the sw ept signal
generator is digitally segmen ted in to 1601 data p oints across the
start/stop frequency span c hosen. Subsequen tly , these p oints are
con v erted in to 1601 reference v oltages for the ALC system. The
digital ALC con trol sc heme not only deliv ers excellen t p o w er
accuracy and atness at the output p ort of the sw ept signal
generator, but also pro vides the means to execute the user atness
correction feature.
Generally , a p o w er meter is required to create a table of correction
data that pro duces at p o w er at the test p ort. Y ou may measure
and en ter correction data for up to 801 p oints. The correction data
con tained in the table is linearly in terp olated to pro duce a 1601-p oint
data array across the start/stop frequency span set on the sw ept
signal generator. The 1601-p oint data arra y is summed with the
in ternal calibration data of the sw ept signal generator ( Figure F-3).
Operating and Programming Reference F-7