JDS Uniphase OneExpert DSL, Руководство пользователя

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Chapter 4 DSL Testing
Testing the physical layer
OneExpert DSL User’s Guide
April 2014 22052280, Revision 001
41
Testing the physical layer
You can use the OneExpert DSL OneExpert DSL to test the physical layer of the xDSL link. The
following procedure describes the basic test for the DSL link.
To perform a basic DSL link test
• Connect to the line and allow the unit to train on the line.
If the unit achieves sync, you have verified the physical layer.
Testing line quality
Once connected to the line, the OneExpert DSL OneExpert DSL gathers statistics for the line.
These statistics are used to determine the line quality.
To test line quality
1 Connect to the line. See “Connecting to the line” on page 39 .
The modem begins the training process automatically. When it reaches show time, the
OneExpert DSL begins gathering statistics.
2 Use the Connection Details and DSL Graph buttons to view different types of statistics.
If the unit achieves sync at the desired data rates, noise margins, and attenuation, the DSL
link is good.
3 Use the Tray menu to save the results. See “Saving results to a job” on page 31 or “Saving a
report” on page 32 .
For more information on the results, see “DSL Results” on page 79 .
Terminating the loop (SELT)
Single End Loop Test (SELT) is used to test a copper loop when there is no equipment installed at
the far end. It is typically used for pre-qualification, that is, testing whether a loop is capable of
supporting DSL service. In some cases, SELT testing is aided by placing a termination at the far
end of the line. This test sets the VDSL modem to provide a line termination where the modem is
idle and not transmitting.
To run a SELT termination
1 On the right panel of the OneExpert DSL, connect one end of the test cable to the DSL
connector, and the other end to the line under test.
2 From the main menu, select DSL , and then select Single DSL .
3 Access the Tray menu by either swiping downward from the top to the bottom of the screen or
by pressing the Tray function key.
4 Select the SELT system key