7.3 fLow & fHigh
(Start & Stop frequency)
fLow
(start frequency) sets the frequency where the sweep should begin, whe-
reas
fHigh
(stop frequency) sets its ending frequency. From these two, the com-
plete
frequency range
which gets sweeped is derived.
Please note that a large frequency range will badly squeeze the display hori-
zontally (in the X axis) and thus significantly reduces measurement accuracy.
Individual signals, especially when close together, will often not be distinguisha-
ble anymore. However, if you narrow the frequency range, you will be able to
analyze the sweep range
more precisely
. You will be able to see far more detail
and
higher accuracy
. A large frequency span is thus mostly useful for a broad
overview,
not for exact measurements
.
7.4 RBW
(bandwidth)
By adjusting
bandwidth
, you can adjust detail clarity and sensitivity at once.
When
bandwidth
is set to a very high value or even to FULL, the sweep will be
very fast, however, the display becomes comparatively inaccurate and sensitivi-
ty is low. Hence, very weak signals will not be picked up anymore. The smaller
the
bandwidth
, the longer the sweep will take, but the display will be more pre-
cise and weaker signals can still be displayed. Thus, for example, a single sig-
nal initially sweeped with high
bandwidth
can turn out to be a number of sever-
al narrow, close together signals. However, this gain in accuracy has its downsi-
de in the far longer sweep times.
Attention: Please note that a few special digital protocols, like e.g. cell
phones, can often be unmeasurable with wrong bandwidth, as the “hit
rate” will dramatically decrease. For these, you should always use high
bandwidth (3MHz) for optimal measurement results.
fLow
(Start frequency)
fHigh
(Stop frequency)
RBW
(1MHz)
RBW
(3MHz)
7.0 The main menu
23
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Summary of Contents for SPECTRAN HF-2025
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