Agilent Technologies 8163A Manual page 206

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Setting Attenuation and/or Power Levels How to Use a Variable Optical Attenuator module
Figure 123 shows an α of 1.651 dB 'added in' to the attenuation factor α to
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calibrate for intrinsic insertion losses in the test setup.
815676A/77A modules
The [PM -> Off ] softkey offered by the α
parameter is functionally equivalent
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to the [PM -> Off ] softkey offered by the P parameter. You can use the [PM -
Offset
> Off ] softkey to offset the difference between the power measured by the
internal powermeter and your reference powermeter, as described "Calibrating
Test Setups that use an 81576A/77A Attenuator module" on page 209.
α α
• When the parameter is selected, [PM -> Off ] writes to
Offset Offset
• When the P parameter is selected, [PM -> Off ] writes to P
Offset Offset
These functions are mathematically identical.
Neither function is a measurement of total intrinsic insertion loss as described in
"81570A/71A/73A/78A modules" on page 204, since the insertion loss of the
Attenuator module itself is not included.
The Dsp -> Off softkey
For all Attenuator modules, the [Dsp -> Off ] softkey offered by the α parameter
copies the negative of the current value of α into α . The α field now displays
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zero, and 'Offs' is displayed to show that the offset has been applied.
You can now set the α parameter relative to α
.
Offset
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Agilent 8163A/B, 8164A/B & 8166A/B Mainframes, Sixth Edition