HP 8901B

Model 8901B Operation
AM
Display Resolution vs. Modulation Output Sensitivity
In Automatic Operation, when the Modulation Output/Audio Input feature is used, the output
autoranges. Autoranging usually occurs between
3.5 and 4 Vpk, open circuit. Many variables, however,
affect the autorange limits and hence the displayed measurement resolution. The variables include:
type of modulation, audio detector, audio filtering, and FM de-emphasis. Special Function
2 permits
manual setting of the audio range.
The following table examines this relationship. (Refer to Audio Range on page 3-183 for more
information on modulation ranges.)
FM 4M
Display
Resolution
Modulation
output
(O/O) (Vac/O/o) (Hz)
Sensitivity
D i s p I a y
Resolution
Modulation
output
Resolution Sensitivity
Display
Modulation
output
Sensitivity
(mVac/Hz) (radians) (mVac/radian)
0.001
0.01' 100 0.0001 10
0.1
-
0.1 10
0.001 1
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0.01 0.1
0.1 0.01
BLOCK DIAGRAM
1 1
10 0.1
0.01 0.1
100 0.01 0.1 0.01
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Modulation OutputlAudio Input Block Diagram
Modulation Output/Audio Input 3-189