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Chapter 3
Structured Cable Field Calibration and Testing
3-36
THE TDR PLOT
The TDR graph is an image of the structure of the cable under test along its entire
length, up to a limit of 2000 feet (609.6 meters). This graph shows anomalies by
displaying blips, peaks, or valleys on an otherwise flat line.
TDR Plot Layout and Controls
The horizontal axis represents distance data and the vertical axis represents the
percentage of reflection.
Figure 3-25: TDR Graphical Plot Layout and Controls
Table 3-6: TDR Graphical Plot Layout and Controls
Item Function
1 Actual TDR data plot for a wire pair. When a wire graph is first displayed, the
cursor is automatically positioned at the midpoint of the data.
2 Designated wire pair plotted from TDR data. (Pair A, B, C, or D)
3 Distance in meters or feet and impedance value at the cursor.
4 The vertical axis represents percentage of reflection data.
5 The horizontal axis represents distance data.
6 Left side of the display shows total length in meters or feet.
Right side of the display shows the minimum/maximum level of Distance of
cursor vs. total length measured in points and associated measured levels of
impedance.
7 Zoom out/Zoom in keys to expand or compress the horizontal axis of the graph
at the cursor.
8 Arrow keys are used to move the cursor horizontally. The screen data displayed
will change to reflect the cursor position.
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