3 Spectrum Analyzer Mode
3.5 ACP Measurement
the VBW filter should be set narrow with less trace averaging, instead of a wide
VBW filter with more trace averaging.
NOTE
Noise Floor Extension has no effect unless the RF Input is selected, so when
External Mixing is selected, it does nothing.
For more details, see "Optimal Detector & Averaging Selections" on page 1088 and
"Recalibration of Noise Floor" on page 1090.
Pros & Cons of Adaptive NFE
Adaptive NFE provides an alternative to fully-on or fully-off NFE. Fully-on NFE can,
notably in cases with little or no averaging of the spectrum, result in a display that is
distractingly unfamiliar in the variability in response to low level signals. Fully-off
NFE fails to achieve the potential improvement in dynamic range and associated
accuracy of measurement of low-level signals. Adaptive NFE controls the degree of
potential improvement in the noise floor to give more improvement for those
instrument settings that can make good use of the potential improvement—those
settings with high degrees of variance reduction through some variant of averaging.
When the potential improvement is small, the display acts like the fully-off case, and
when it is high, it acts like the fully-on case, and in-between, application is a
compromise between attractiveness and effectiveness.
In Adaptive NFE, there is not the same dramatic visual impact on the noise floor as
there is in Full NFE. Adaptive NFE controls the amount of correction that is applied
based on other instrument settings like RBW, averaging and sweep time. Adaptive
NFE controls the degree of potential improvement in the noise floor to give more
improvement for those instrument settings that can make good use of the potential
improvement, such as settings that provide more averaging. The result is that when
not much averaging is being performed, the signal displays more like the fully-off
case; and when lots of averaging is being performed, the signal displays more like
the Full NFE case.
Adaptive NFE is recommended for general-purpose use. For fully-ATE (automatic
test equipment) applications, where possible distraction of the instrument user is
not a risk, Full NFE is recommended.
NFE On/Off Command
Remote Command
[:SENSe]:CORRection:NOISe:FLOor ON | OFF | 1 | 0
[:SENSe]:CORRection:NOISe:FLOor?
Example
:CORR:NOIS:FLO ON
Dependencies Only appears in instruments with the NFE or NF2 license installed. In all others, the control does not
appear. In those cases, the SCPI command is accepted without error, but has no effect
Couplings When NFE is enabled in any Mode manually, a prompt is displayed reminding you to perform the
Spectrum Analyzer Mode User's &Programmer's Reference 1087
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