288 Chapter4
Key Function Descriptions
Key Descriptions
WEIGHTNG √ COS OFF Turns on or off the function that does
root-raised-cosine weighting of the spectrum data for
an ACP measurement. This weighting simulates the
filtering expected in the radio receiver to be used.
Front-panel key access:
MEAS/USER
The root-raised-cosine weighting function is described
by the following equations:
The resolution bandwidth of the spectrum analyzer is
of a finite width. Therefore, we compensate slightly for
α and for the threshold of the zero response:
ZERO SPAN Sets the span to 0 Hz. This effectively allows an
amplitude versus time mode in which to view signals.
This is especially useful for viewing modulation.
Front-panel key access:
SPAN
W ∆f()
∆f
1 α–
2T
------------
W ∆f()→≤ 0dB=
1 α–
2T
------------
∆f[]
1 α–
2T
------------
∆f[] 10dB()log
10
1
2
---
1
π 2 ∆fT 1–()
2α
----------------------------------
sin–
=→<<
1 α–
2T
------------
∆f ∆f ∞dB–=→≤
=
1 α–
2T
------------
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