N9069C Noise Figure Measurement Guide 59
Measurement Related Tasks and Concepts
Setting the Measurement System
When to Perform Calibration
To make corrected measurements, you must calibrate the analyzer whenever:
— You power cycle the analyzer
— You preset the analyzer
— You select a measurement frequency or frequency range outside the
currently calibrated range
— There is a large temperature variation since the last calibration
— The input signal level can no longer be measured using one of the
calibrated input attenuator ranges
— When an invalid result is detected and the condition is indicated by a “xx”.
Interpolated Results
When the location of the measurement points is changed without exceeding
the range of frequencies being measured, interpolation between calibration
points is used and a new calibration is not required.
The locations of the measurement points, that is, the frequencies at which
measurements are made, change whenever the start frequency, the stop
frequency, or the number of sweep points is changed.
Calibration Indicator
Whenever anything within the analyzer changes to invalidate the current
calibration, the
CAL STATE
displays
UNCAL
in red at the top of the display. If
the analyzer has been successfully calibrated for the current frequency and
measurement settings, the
CAL STATE
displays
CAL
in green text at the top of
the display.
Interpolated Calibration
Whenever anything within the analyzer changes to force the current calibration
to interpolate the calibration data, the
CAL STATE
green
CAL
message at the
top of the display switches to a yellow
~CAL
message. This would happen, for
example, if you change the RBW after calibrating but before measuring.
User Cal vs. Internal Cal
User Cal is the most commonly used calibration method. For the X-Series used
with the USB Preamp there is another calibration method available, Internal
Cal. See
for a comparison between User Cal and Internal Cal.
Summary of Contents for CXA N9000B
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