Chapter 3 Spectrum Analysis Operation
Selecting RBW, VBW and SWT
9102 Handheld Spectrum Analyzer Software version 5.31
59
2 Push the FStep key.
The Freq Step entry field opens.
3 Enter a new frequency step value and close the entry field by
pressing the appropriate enter key determining the unit (GH
Z/DBM
for gigahertz, MH
Z/DB/ΜS for megahertz, KHZ/DBΜV/MS for kilo-
hertz, or E
NTER for hertz).
The auto/manual selection switches to manual and the selected
frequency step size is displayed on the softkey.
Setting the frequency step size selection to automatic
1 From the main menu, select
Freq.
2 Push the
FStep softkey several times until the “auto” selection is
highlighted.
Selecting RBW, VBW and SWT
The resolution bandwidth (RBW) is the 3 dB bandwidth of the IF filter
for selecting the signal to be measured. The resolution bandwidth
describes the ability of the spectrum analyzer to discriminate between
adjacent signals of similar amplitude. Only signals spaced at a
frequency of more than the RBW can be discriminated from one
another.
The 9102 can be set to automatically select the resolution bandwidth,
depending on the frequency span.
The video bandwidth (VBW) is the lowpass bandwidth over which
several results for one frequency point are smoothened. The lower the
video bandwidth, the smoother the signal curve and the less variations
there are.
The 9102 can be set to select the video bandwidth automatically as a
function of the resolution bandwidth.
The sweep time (SWT) determines how long it takes for a complete
sweep over the measured frequency range (span).
The 9102 can be set to automatically select the sweep time, depending
on RBW and VBW. If manually set, the sweep time should be selected
long enough for the filtered signal to reach steady state. The 9102 will
output an “UNCALibrated” warning if the sweep time is too low.
To set the resolution bandwidth, the video bandwidth or the sweep
time, proceed as follows:
1 In the main menu, select the appropriate softkey (
RBW, VBW, or
SWT).
2 Enter the value and complete the entry with the appropriate enter
key for the unit, select a new value with the help of the U
P/DOWN
cursor keys, or switch to
auto to leave the setting to the 9102.
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