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Model 8902A
Operation
AM Calibration
FUNCTIONS
CALIBRATE, SAVE CAL, Yo CAL FACTOR, Special Functions 13 (AM Calibration) and
16
(AM
Calibration Factors).
DESCRIPTION
The accuracy of the Measuring Receiver's AM demodulator can be checked with the internal
AM calibrator. The calibration process generates a calibration factor to compensate for the AM
measurement error (within the accuracy limits of the AM Calibrator). Using the SAVE CAL key or
Special Function 16, the calibration factor can then be enabled to automatically correct the measured
AM error in subsequent measurements. With the calibration factor enabled, AM measurements can
be made with an accuracy typically better than 0.5%. The calibration factor can be enabled, disabled,
or
displayed at any time.
Other instruments in the HP
8901
and 8902 R F signal analyzer family can be calibrated o r cross
checked using Special Function 13.
PROCEDURE
Self-calibration
To
determine the measurement error of the Measuring Receiver's AM demodulation circuits, first
allow at least a half-hour continuous operation before calibration, then perform the following steps:
1.
Connect the CALIBRATION AM/FM OUTPUT to the RF INPUT with a
50R
cable (or a
2. Select CALIBRATE. After several seconds, the AM calibration factor is displayed in
% o
and
The instrument displays iOO.OOo/o if no error is measured. A display of 100.17% means the AM
demodulator in the Measuring Receiver is reading
0.17%
high. As long as the CALIBRATE key
light is on and the cable is connected, calibration repeats and the AM calibration factor is updated
approximately every 17 seconds. To turn
o f f
the calibrator, select CALlBRATE o r any Measurement
key.
sensor module with an internal switch such as the HP I1722A) and select AM.
stored (but not enabled unless already enabled).
NOTE
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Correcting Measurements with the AM Calibration Factor. Once a calibration factor has been
determined, the instrument retains that value in its non-volatile memory. This factor may be enabled
to automatically correct AM measurements. The calibration factor can also be disabled o r displayed.
Selecting
O/o
CAL FACTOR or 16.2 SPCL displays the calibration factor being used.
3- 167
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