84 N9912A FieldFox User’s Guide
o Auto Res BW is coupled to the frequency span. As the frequency span is
narrowed, the Res BW is also narrowed providing increased ability to
resolve signals.
To change this setting from Man to Auto, press Res BW twice.
o Man Enter a Res BW value using the numeric keypad, the ▲|▼ arrows, or
the rotary knob. Then press a multiplier if necessary or press Enter .
The current Res BW setting is shown at the bottom of the screen.
#Res BW x.xx XHz ( # ) means manual setting.
This setting could impact the accuracy of the measurement. See Specifications on
page 178.
NOTE The Res BW setting also affects the Sweep Type setting. Learn how on page 84
Video Bandwidth (Video BW)
Video BW is a smoothing operation that is performed after measurement data is
acquired. The trace data is effectively smoothed so that the average power level
of the displayed noise is the same, but the peaks and valleys of adjacent data
points are smoothed together. More smoothing occurs as the Video BW is set
lower. However, as the Video BW is narrowed, the sweep speed becomes slower.
How to set VBW
Press BW 2.
Then Video BW Auto Man.
o Auto Couples Video BW to the ResBW in a 1-to-1 ratio.
o Man Enter a Video BW value using the numeric keypad, the ▲|▼ arrows,
or the rotary knob. Then press a multiplier if necessary or press Enter.
NOTE To change this setting from Man to Auto, press Video BW twice.
The current Video BW setting is shown at the bottom of the screen.
# VBW x.xx XHz ( # ) means manual setting.
When the Res BW/Video BW ratio exceeds 10,000, a Meas UNCAL warning may
appear to indicate that the Video BW filter has reached the maximum capacity
for averaging.
In Zero Span, the maximum Res BW/ Video BW ratio is 100.
Sweep Type
In SA mode, the FieldFox uses two sweep types to process inputs signals. The
sweep type that is currently being used (FFT or Step) is displayed in the lower-
left corner of the FieldFox screen.
For a more comprehensive tutorial, see Spectrum Analysis Basics (App Note 150)
at http://cp.literature.agilent.com/litweb/pdf/5952-0292.pdf
How to set Sweep Type
Press BW 2.
Then Advanced
Then Sweep Type Auto FFT Step
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