42 Keysight N9938-90003 User’s Guide
CAT (Cable and Antenna Test) Mode
CAT Mode Settings
— Ref Level Manually set the value of the reference line.
Enter a negative value by pressing Run/Hold (+/-)
either
before or after typing a value
— Ref Pos
Manually set the position of the reference line.
Values must be between 0 (TOP line) and 10 (BOTTOM
line)
3. Set Top and Bottom graticule values. The scale per division is
calculated.
— Top
to set the value of the Top graticule.
— Bottom
to set the value of the Bottom graticule.
— Enter a negative value by pressing Run/Hold (+/-)
either
before or after typing a value.
Averaging
Trace Averaging helps to smooth a trace to reduce the effects of random noise
on a measurement. The FieldFox computes each data point based on the
average of the same data point over several consecutive sweeps.
Average Count determines the number of sweeps to average; the higher the
average count, the greater the amount of noise reduction.
An average counter is shown in the left edge of the screen as Avg N. This
shows the number of previous sweeps that have been averaged together to
form the current trace. When the counter reaches the specified count, then a
‘running average’ of the last N sweeps is displayed. Average Count = 1 means
there is NO averaging.
This setting can be changed at any time without affecting calibration accuracy.
How to set Trace Averaging
—Press BW 2.
Scale annotation on the FieldFox screen
Reference Line = red arrow
Ref Level = -40 dB
Ref Position = 1
Scale = 2 dB per division
Averaging is often used to increase the dynamic range of a measurement.
To achieve the highest dynamic range, select NA mode and reduce the IF
Bandwidth setting. Learn more about dynamic range in
“Increase Dynamic
Range” on page 86
.
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