Chapter 3
Calibration, Configuration, and Special Operations
3-49
Viewing TDR Results
When the TDR diagnostic function is first started, the graphical plot is
automatically scaled to the full length of the cable. A maximum of 2000 feet (609.6
meters) of cable results can be displayed on a TDR graph.
When TDR is first activated, the left 10% of the graph displays prelaunch
impedance signal rise distance data and the right 10% of the graph displays
reflection data.
• Press the Left/Right Arrow keys to move the cursor horizontally. As the
cursor moves, screen data displays will change to reflect cursor position.
• Press the Up/Down Arrow keys to view TDR results from a different wire
pair. The TDR test runs one time and displays the results.
• Press the Zoom keys to scale the graph. At the maximum or minimum limits
the key becomes inactive.
• TDR results can be saved to a PC and printed.
Interpreting TDR Results
Always note the cable pair currently being displayed. The shape of the reflections
plotted for the pair can be used to identify and locate problems. If the cable pair
has no problems along the entire length of the pair, then the graph will appear as
follows:
• The graph has an upswing point on the left most 10% of the display (Start of
the Cable).
• The following 80% of the graph is relatively flat.
• The graph has an upswing or downswing point on the right most 10% of the
graph (End of the Cable).
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