OMNISCANNER User Guide
6 - 4
Use or to select which end, OMNISCANNER or OMNIREMOTE,
you want to view the results for.
Press to open the TDNXT screen.
The screen displays the TDNXT (Time Domain NEXT) graph. The funnel-
like lines are the upper and lower S-Bands. S-Bands are limit lines for
connections as a function of distance from the cable end. They provide
a quantitative measure of the NEXT at the connection point, which is
typically located at the end of the test cable at 2 meters (7ft). The
measurement unit for the horizontal graph can be displayed in meters
(m) or feet (ft.). (See Chapter 4 - Setup: User Options for further
information about units.)
Initially, the cursor is located at the point with the worst NEXT.
The NEXT at the cursor position relative
to the S-Band, the corresponding pair
combination, and the distance to the
cursor position are displayed above the
graph.
The example shows a Time Domain
NEXT that exceeds the S-Bands. The
worst NEXT is displayed at 7ft, the
connection location. The conclusion is
that the connection caused the failure.
Press ESC to exit the TDNXT screen.
Using TDNXT to Diagnose a Link
The S-Band limit lines provide an easy method to pinpoint faults
located at the connection or the cable. S-Bands allow you to determine
if the connections in a link meet the desired performance level. They
are designed to match the standard category of the selected Autotest.
A graph containing peaks that are located outside the S-bands at the
connection distance indicates that the connection and not the installed
cable is the most likely reason for failure.
If NEXT failed but the TDNXT graph displays peaks within the S-Bands
at the connection distance, the fault is caused by the cable portion of
the link.
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