R&S ZVB - Page 187

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ZVA / R&S
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ZVB / R&S
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ZVT GUI Reference
Trace Menu
Operating Manual 1145.1084.12 – 30 172
Set Harmonic Grid
In the Set Harmonic Grid... panel of the Low Pass Settings dialog, a harmonic grid can be calculated in
three alternative ways:
 Keep Stop Frequency and Number of Points calculates a harmonic grid based on the current stop
frequency (Channel – Stimulus – Stop) and the current number of sweep points (Channel –
Sweep – Number of Points). This may increase the frequency gap (the spacing between the
equidistant sweep points, i.e. the sweep Span divided by the Number of Points minus one) .
 Keep Frequency Gap and Number of Points calculates a harmonic grid based on the current
frequency gap and number of points, modifying the stop frequency (Channel – Stimulus – Stop).
 Keep Stop Frequency and Approximate Frequency Gap calculates a harmonic grid based on the
current stop frequency (Channel – Stimulus – Stop), increasing the number of points (Channel –
Sweep – Number of Points) in such a way that the frequency gap remains approximately the
same. This may increase the sweep time, due to the additional sweep points introduced.
The three grids can be calculated repeatedly in any order; the analyzer always starts from the original set
of sweep points.
Visualization of the harmonic grid algorithms
The three types of harmonic grids have the following characteristics:
 Keep Stop Frequency and Number of Points means that the stop frequency and the number of
sweep points is maintained. The sweep points are re-distributed across the range between the
minimum frequency of the analyzer and the stop frequency; the step width may be increased.
 Keep Frequency Gap and Number of Points means that the number of sweep points and their
relative spacing is maintained. If the start frequency of the sweep is sufficiently above the f
min
, the
entire set of sweep points is shifted towards lower frequencies so that the stop frequency is
decreased.
If the start frequency of the sweep is close to f
min
, then the sweep points may have to be shifted
towards higher frequencies. If the last sweep point of the calculated harmonic grid exceeds the