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4-2
Calibration
Calibration
RF Power Calibration
The RF Power calibration procedure is shown in Chapter 2 of this
guide. Once the procedure has been completed it does not need to be
repeated again unless you change Sensor Modules or the calibration
factors for the Sensor Module you are using change (due to repair
or recalibration of the Sensor Module). (If the Sensor Module or
the calibration factors are changed, you will need to complete the
calibration factor entry procedure provided in Appendix B before
proceeding with the calibration procedure shown in Chapter
1.)
To Maintain Accuracy
To maintain calibration accuracy,
it
is necessary to periodically press the
ZERO key (approximately once every ten minutes while making RF Power
measurements is recommended and each time you connect the sensor to
a different output port). Pressing the ZERO key enables the HP 8902A
to compensate for any inherent, dc-offset error in the measurement
system caused by changes in the ambient operating temperature.
Tuning
You may remember that in Chapter 2 you were told that the HP 8902A
should be tuned to the frequency of the input signal when making RF
Power measurements. Even though the RF Power measurement is not
a tuned measurement, the instrument uses the frequency setting to
determine the appropriate calibration factor to select from the table of
power sensor calibration factors stored in its memory. (If a calibration factor
is not stored for the specific frequency being measured, the HP 8902A
derives a calibration factor by linear interpolation between the closest cal
factors in the storage table on both sides of the measurement frequency.)
TRFL Calibration
The TRFL calibration procedure is described in Chapter
1.
Table 4-1
will
help you remember the key steps to calibrating your TRFL measurements.
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Chapters
