HP 8901B

Model 8901B Operation
COMMENTS
Audio Range Effect on Distortion Measurements
The selected Audio Range has no effect on audio distortion or SINAD measurements.
When the audio range selected is too high for the level of the audio signal, the signal-to-noise ratio
will be low (no error
is generated). (The output of MODULATION OUTPUT/AUDIO INPUT tracks
the displayed values.) When the audio range
is too low for the audio signal level, Error 04 is generated.
(The output of the MODULATION OUTPUT/AUDIO INPUT
will probably be clipped.) Depending
on the audio filtering and detector in
use, Error 04 may not be generated at exactly the nominal values
listed in the tables above.
Disabling Error 04 Inhibits Audio Autoranging
When Error 04 is disabled (refer to Error Message Disable Control on page 3-233), the Modulation
Analyzer automatically ranges
to a less sensitive range when the signal level requires, but it does not
range back when the audio level
is reduced. This feature is used most often when modulation varies
widely with time (such
as off-the-air demodulation of a broadcast signal).
Audio Range 3-185