Tektronix RFM220, Руководство пользователя

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Operating Basics
Special graphs.
Constellation and spectrum graphs enable you to identify
modulation problems such as amplitude imbalance, quadrature error, coherent
interference, phase noise, amplitude noise, phase error and MER problems.
Left and right shoulder measurements are displayed in dB to help indicate if
there are spectrum mask issues.
NOTE.
Special graphs are shown properly only if the instrument is online.
Special graphs for Of fl ine instruments will show a “Loading Data” message.
If a special graph is already open and showing data when an instrument
goes of
fl ine, the special graph will continue to show the old data or the last
graph obtained.
If the RF input signal to the RFM220 instrument is not proper or if RF lock to
the signal is lost, the Constellation graph will not show data and a “Loading
Data” message will be continuously displayed. A possible cause of this
problem in an inaccurately tuned channel frequency. Use the Con
fi guration
menu to edit the channel plans and tune channel frequencies. (See page 58,
Con
fi guration Menu.)
Changing the Graph
Layout
Change Layout menu.
Use the Change Layout drop-down list to select one of
the following layouts:
Horizontal
Vertical
Tiled Horizontal
Tiled Vertical
Pane controls.
Allows you to completely collapse or expand the pane
boundaries. You can adjust the pane sizes by dragging and dropping the pane
boundaries. (See Figure 31.)
Graph selection. Click on a graph to select it. The selected graph will have
a red line around the graph.
Error range indicators.
The Error Range Indicator check box is only available
when a trend graph or the Delay Pro fi le graph is seleted. When the error
range indicators are displayed, the error thresholds are indicated by red areas
on the graph.
Trend timescales.
The Trend Timescale drop-down list is only available when
a trend graph is selected. The following time scales are available:
Previous minute
Previous ten minutes
Previous hour
Previous day
Previous week
68 RFM220 User Manual