HP (Hewlett-Packard) 86140A TV Cables User Manual


 
3-13
Using the Optical Spectrum Analyzer
The Amplitude Menus
Auto Chop Mode
Enables the spectrum analyzer chop mode. Chop mode increases dynamic
range for long sweep times by subtracting ambient light. Subtracting the ambi-
ent light can improve sensitivity but slow down the sweep speed.
Pressing the front-panel
Preset
key turns this function
OFF
.
Power Calibration
Power Calibration allows you to use amplitude correction factors either from
the factory calibration or from the last successful user calibration. Pressing
the front-panel
Preset
key resets this function to User. If a user calibration has
not been performed, the factory calibration data is used.
User Power Cal Date
The User Power Cal Date displays the date of the last successful user-per-
formed amplitude calibration. See To perform a power calibration on
page 3-44 for information on performing an amplitude calibration.
Note
The optical spectrum analyzer performs a more complete zeroing when the instrument is
first turned on. You can run this more complete routine anytime by pressing the
Zero
Now
softkey. Refer to To zero the instrument on page 3-50 for more information.
Note
Sweep times of 50 msec × the # of trace points, or longer, use a special chop mode.
Chop mode increases dynamic range, stabilizes measurements against drift, and reduces
effects of stray light. This special chop mode is enabled by setting the Auto Chop mode
to
ON
.
book.book Page 13 Monday, January 31, 2000 10:34 AM