General Signal Viewing > DPX Spectrum
DPX Primer
Figure 22. The marker was positioned by selecting the Peak button. Density, frequency, and amplitude measurements
at the marker are displayed in the upper left corner of the graph.
The Marker Toolbar, at the bottom of Figure 22, allows easy navigation of peak signals (
Peak Left
,
Peak
Right
,
Next Peak Up
, or
Next Peak Down
). Selecting the arrow keys enables the marker to search for
amplitude/density peaks at other frequencies, while the
Next Peak Up
and
Next Peak Down
arrows
enable the marker to search for other high-density points at the same frequency.
In the De
fi
ne Peaks tab of the De
fi
ne Markers control panel, Figure 24, you can adjust the density threshold
and excursion controls to modify search behavior. The amplitude threshold and excursion controls also
apply to DPX marker searches. Smoothing keeps the marker from
fi
nding multiple peaks within the same
apparent signal by averaging an adjustable number of pixel densities together, but it does not affect the
single-pixel measurement readout displayed by the marker.
Figure 24. Amplitude and Signal Density controls can be adjusted to de
fi
ne Peak search behavior.
Density Measurements over an Adjustable Area (“The Box”)
The density for a single pixel is its ratio of actual hits vs. possible hits over a de
fi
ned time period, and
markers display these density values. For measuring density over an area larger than one pixel, Option 200
includes a measurement box you can resize and drag around in the DPX Spectrum display with your
mouse or
fi
nger.
If you could make the box so narrow that it contained only points within a single column of pixels, the
density of this area would be the sum of the included pixels’ density values. For example, if the box was
three pixels tall and the density values for these pixels were 4, 2, and 7% respectively, the overall density
for the three-pixel area would be 13%. Imagine a box one pixel wide and as tall as the graph. Assume that
the input signal’s amplitude was such that all hits fell at or near the vertical center of the screen. Since
100% of the waveforms written to the bitmap passed through the box, the density for the box is 100%.
RSA6100A Series Real-Time Spectrum Analyzers Help
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Summary of Contents for RSA6100A Series
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