Tektronix RSA5100A Series, Quick Start User Manual

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Operation
The quickest way to set up a DPX Density trigger is to use a mouse and right-click on a signal of interest in the DPX
graph, or press on the screen and hold with your
fi nger for one second. A menu will pop up. Select Trigger On This .
This action performs several tasks:
Places the density measurement box at the click point
Sets the measurement box to its default size
Measures the average density in the box
Sets the Trigger mode to Triggered
Selects the DPX Density "Higher" trigger type
Adjusts the trigger threshold to a density value slightly below the current measured value
Starts the acquisition process
To optimize DPX Density trigger settings for your particular signals, open the Trigger control panel. Use the controls for
changing the polarity of the trigger’s threshold comparison (Higher versus Lower), the Threshold value, and the size and
location of the measurement box. Use the Frequency and Amplitude settings to locate the center of the box, and set the +/-
values to adjust the width and height of the measurement box.
For events that are partially masked by stronger signals, you will often need to adjust the density Threshold based on
density measurements of the event of interest and of the obscuring signal. For example, if the density of the background
color representing only the stronger signal is 7% and the density measurement including both signals is 9%, you would
set the Threshold to 8%.
If your expected signal is a continuous tone and you want to capture events when it hops to a different frequency or drops
to a lower amplitude, move the Density measurement box to surround the peak of the signal, select
Lower in the Density
control, and set Threshold to 100%. The instrument will trigger when the signal is absent from the measurement box.
Hint.
The density measurement is the average of the densities for each column of pixels in the box. If your measurement
box is wider than the peak of a CW signal, the density reading will be less than 100%. To get a 100% reading, you can
broaden the peak by increasing RBW or narrow the box until there are no colored pixels either above or below the box. The
signal should enter the left side of the box and exit the right side. It should not cross the bottom edge of the box.
50 RSA6100A Series & RSA5100A Series Quick Start User Manual