Agilent Technologies 8614 B Series, Руководство пользователя, Страница: 148 / 272

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Function Reference
Select Path INT/EXT
Select Path INT/EXT
For 86146B only.
Allows you to select between internal (50 µm) and external (9 µm) fiber. The dual fiber outputs
from the monochromator allow the instrument to have improved resolution bandwidth and
dynamic range when using the 9 µm fiber. The 50 µm fiber is the default setting.
Internal (50 µm) path resolution bandwidth include: 0.06, 0.1, 0.14, 0.2, 0.33, 0.5, 1, 2, 5, 10
settings
External (9 µm) path resolution bandwidth include: 0.04, 0.06, 0.1, 0.14, 0.2, 0.33, 0.5, 1, 2, 5,
10 settings
Key Path Bandwidth/Sweep > Select Path
Remote Commands INSTrument:SELect “FILTER”
Sensitivity
Requests the lowest amplitude signal that can be measured relative to the power at “top of
screen”. It is defined as the signal that is six times the RMS noise. The minimum setting is –100
dB. An error will be reported for values outside of this range and the sensitivity will round to the
nearest valid sensitivity.
See “Setting the Sensitivity” on page 2-8
Manual allows manual input of sensitivities and enables auto gain ranging. The “top of screen”
and the sensitivity setting determines the requested dynamic range. The system will sweep once
per gain stage and may require up to three sweeps to achieve the requested dynamic range.
Auto automatically chooses a sensitivity and a single gain range based on “top of screen”. This
will result in approximately 40 dB of dynamic range.
The sweep time (ST) that is displayed in the lower portion of the display is the time for the OSA to
sweep over one gain stage. The OSA may take up to three sweeps in three different gain stages
to make the measurement. This depends on the settings for sensitivity, reference level, auto
range and also the particular device being measured. The final data trace is a blended composite
of each trace taken in the different gain stages. For more information
refer to “Setting the Sensi-
tivity” on page 2-8 .
An increase in sensitivity may also require a narrower video bandwidth, which will slow the
sweep speed. Normally, the optical spectrum analyzer selects the greatest sensitivity possible
that does not require amplification changes during the sweep. If you manually increase the sensi-
tivity level, the sweep pauses to allow this change in gain.