HP 8530A, Руководство по эксплуатации и программированию, Страница: 312 / 439

Controls that Aect the Receiver
W arning Beeper
The
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BEEPER ON /
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OFF softkeys control whether you hear a \beep" whenever a warning
message is displayed. The BEEPER ON position is the factory default.
IF Calibration and Correction
IF calibration/correction is an automatic calibration feature that reduces IF gain and
quadrature errors in each of the four input channels (a1, a2, b1 and b2). This process is
composed of two features:
IF Calibration IF calibration measures a crystal reference signal and determines gain a
quadrature errors for each input channel. A series of error-correction
coecients are calculated. The receiver rmware determines how often
IF calibrations should be performed. When the receiver is warming up , it
performs IF calibrations often. When the receiver is fully warmed up , it
performs IF calibrations less often.
Refer to Figure 2-1 . T o perform an IF calibration, the receiver measures a
100 kHz reference signal (from a built-in crystal oscillator) with the T est and
Reference Synchronous Detectors . Then, IF calibration calculates gain and
quadrature errors for each input channel.
The receiver inhibits periodic IF calibrations during F ast CW modes . The user
can also turn periodic IF calibrations OFF . Y ou can also force an IF calibration
to be performed. Refer to the \IF Calibration Controls ," below , for instructions .
IF Correction IF Correction subtracts IF calibration error coecients from the measurement
data. IF correction is always ON. IF correction occurs before any other data
processing, before data reaches the Raw Data Arrays .
IF Calibration Controls
Press 4 SYSTEM 5
N
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IF CORRECTION to access the IF Calibration controls , which are described
below:
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RESET IF CORRECTION This softkey initiates an IF gain calibration before starting the
next group of sweeps .
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IF CORRECT: AUTO
This is the factory-default setting. When A UTO is selected,
the receiver automatically performs IF calibrations at periodic
intervals .
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IF CORRECT: MANUAL This setting stops IF calibrations from occurring automatically .
Y ou can manually perform an IF calibration by pressing:
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RESET IF CORRECTION
Even if Manual mode is selected, the receiver still modies measurement data with the
most-recent IF calibration coecients .
Using System Functions 17-5