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


 
3-12
Using the Optical Spectrum Analyzer
The Amplitude Menus
Setup panel
selections
Reference Level Position
The value selected for the Reference Level Position determines the position of
the reference level on the graticule. Setting this value to zero divisions places
the reference level on the very bottom of the grid. Setting the reference level
to 10 divisions places the reference level at the top of the grid. Pressing the
front-panel
Preset
key resets the reference level to 9.0 divisions.
Amplitude Units
Selecting Auto for amplitude units allows power to be shown in dBm when
using the logarithmic scale and in watts when using the linear scale. Selecting
W forces the readout to be in watts, regardless of the amplitude scaling.
Auto Ranging
The Auto Range function allows the OSA to change the gain of the transim-
pedance amplifier during a sweep. This provides measurements to be made at
the widest dynamic range and at the fastest sweep speed.
Pressing the front-panel
Preset
key turns Auto Ranging
ON
.
Auto Zero
Turns Auto Zero
ON
and
OFF
. Auto Zero
ON
enables the internal amplifiers to
be zeroed between sweeps. Selecting
OFF
disables this feature. Pressing the
front-panel
Preset
key resets this function to
ON
.
Note
When using the knob or step keys, the value will automatically change. When using the
numeric entry pad, a terminator must be selected from the softkey panel.
Note
It is recommended that Auto Ranging always be turned
ON
.
Note
Turning Auto Zero
OFF
allows the instrument to sweep faster, but results in less accu-
racy on low level signals.
book.book Page 12 Monday, January 31, 2000 10:34 AM