Tektronix SPECMON3 Manual page 77

General Signal Viewing
Item Display element
1 Spectrums/line
2 Color scale
3 DPXogram trace
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Time Resolution of DPXogram Display
Due to the large amount of data produced by the DPX hardware during acquisitions, a compressed version
of the plot is shown while running. This plot is limited to 500 lines, with each line having 267 points.
However, a much longer record, with higher frequency resolution is being collected. As soon as the
instrument is stopped, this underlying data is shown, replacing the temporary version. There are 50 lines
in each vertical division of the 2-D DPXogram plot, so the time resolution of the graph is Time/div
divided by 50. However, you can set the instrument to collect multiple spectra per line, allowing you to
zoom in later on this high-time-resolution data.
When the DPXogram display is stopped, the analyzer can display the full resolution of the captured data.
The Time Resolution readout applies only when the DPXogram is running.
Effects of Changing Time Resolution.
DPX hardware. This means that if you change the Time Resolution value while the instrument is stopped,
the new value applies to the NEXT acquisition, and might not represent the results currently shown in
the display.
Time resolution can be changed either directly, by manually adjusting the Time Resolution control, or
automatically, by changing the Time/div control. Auto is the default, yielding one spectrum per line in the
display. When the Time Resolution is decreased below its auto value, multiple spectra are collected to
create each line in the DPXogram graph. Once you stop the instrument, you can decrease the Time/div
value or use Zoom to see increased time resolution.
If the time resolution is set to a very small number while the Time/div is set to a large value, you might
notice that there is a limit to the number of spectra that can be collected. This limit depends on the number
of trace points selected. For 801-point spectra, 60,000 underlying spectra can be collected. The number of
2401-point spectra collected is 20,000, and for 4001-point spectra the number is 12,000. When the limit is
reached, the oldest spectra are discarded as newer spectra are captured.
SPECMON3 & SPECMON6 Printable Help
Description
Appears only when the display is stopped. Readout of the number of spectrum
lines represented by each line of the DPXOgram display. This value changes
when the Time/div or Time resolution settings are changed.
Legend at the right side of the DPX Spectrum display. This element illustrates the
relationship between the colors in the DPXogram plot and the amplitude axis of the
DPX Spectrum plot. This scale changes with Color (DPXogram) palette selection
and Max and Min settings on the Ampl Scale tab.
The selected line in the DPXogram graph can be shown in the DPX Spectrum
graph of the Split view. The most recent DPXogram line, usually at the bottom
of the graph, is selected by default. If any markers are on, the selected marker
determines the selected line.
The Time Resolution control affects acquisition parameters for the
DPX Display
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