Anritsu MS2024A/MS2026A User Manual page 151

Chapter 4 — Spectrum Analyzer
the previously active point, until the selected active point is on the left side of the
display.
Next Point Right
This soft key selects the limit point that is immediately to the right of the current
active point, making this newly selected point active for editing or deletion. With
each key press, the selection of the active point moves to the right of the
previously active point, until the selected active point is on the right side of the
display.
Back
Press this soft key to return to the Limit soft key menu.
Limit Envelope
A limit envelope is very useful when you want to easily detect new signals in the
presence of other preexisting signals. Use the limit envelope function to automatically
create upper or lower limit lines that are based upon the on-screen measured spectrum
analysis values. For a display example of a limit envelope, see
Limit Envelope, Square" on page
soft key menu.
Create Envelope
Press this soft key to generate the envelope using the Limit Envelope
characteristics. If the default results are not satisfactory, then you can make
adjustments to the amplitude and frequency of each inflection point, and you can
add or delete inflection points.
Update Envelope Amplitude
While working on your envelope (or if your signal amplitude changes), you may
want to adjust the amplitude of the current limit without changing the
frequencies of the inflection points. Pressing this soft key makes those amplitude
adjustments without frequency adjustments.
Update Square Envelope Frequency
Press this soft key to adjust the envelope frequency. If the magnitudes of two
adjacent limit inflection points are the same (a horizontal line), then the
frequencies of the next two limit inflection points are tested.
If the magnitudes of two adjacent limit inflection points are further than two
sweep points apart (a gradual slope indicating a narrower span), then the second
inflection point is brought back closer to the first inflection point so that the slope
increases to near vertical.
If the magnitudes of two adjacent limit inflection points are closer than two
sweep points apart (so close that the second inflection point may not be able to be
displayed), then the second inflection point is pushed further out from the first
inflection point so that the slope becomes near vertical.
If the user has adjusted the magnitude of some limit inflection points so that the
horizontal lines are no longer horizontal, then the algorithm will probably have
difficulty with the update, and unintended results may occur.
MS20xxA VNA Master UG 10580-00166 Rev. C
4-41. Press this soft key to open the Limit Envelope
4-25 Limit
Figure 4-14 "Example
4-39