Loopback Test Procedures; General Troubleshooting Tips; Gnlb Test Procedures - ADC H2TU-C-202 User Manual

LTPH-UM-1161-01
Loopbacks can be terminated manually and exited from the MAN LPBK mode by simultaneously pressing the
MODE and LBK pushbuttons for 3 or more seconds. If no loopback is active, the MAN LPBK mode automatically
terminates after 30 seconds.
All loopbacks, except dual loopbacks, can be initiated by inband commands in the DS1 payload. Loopbacks can
also be initiated by a command from the HDSL2 system using front-panel pushbuttons or maintenance screen
selections. Therefore, whenever a loopback is active, the method by which it was activated is indicated in the
Loopback and Status screens by the annotation HG or PL adjacent to the identified loopback. For example,
NREM-HG indicates that the loopback was initiated by the HDSL2 system.
SMJK loopback commands are only activated by inband commands. Dual loopback commands
are only activated by the front-panel pushbuttons or maintenance screen selections.
L T
OOPBACK EST
The following sections provide step-by-step test procedures for verifying the integrity of the HDSL2 channels at
every module location as well as the DS1 channels to the customer and the local DSX-1 interface.

General Troubleshooting Tips

If trouble is encountered on the DSX-1 interfaces of the H2TU-C, verify that the:
•
H2TU-C is making a positive connection with its mounting assembly (shelf) connector.
•
H2TU-C internal equalizer is set to the correct distance range per
be set to the distance from the DSX-1 to the shelf.

GNLB Test Procedures

Figure 32 on page 56
GNLB commands shown. See
To perform the GNLB loopback test procedure:
1 Have the CO tester send the NREM (3-in-7) inband loopup code for 5 seconds. Observe the NREM message
on the front-panel display. The Status LED on the front panel should be green, and the loopback mode should
also be identified on the Monitor screen.
2 Have the CO tester transmit a DS1 test signal toward the H2TU-C and verify that the returned (looped) signal
to the test set is error-free.
3 If Step 2 fails, have the CO tester transmit the (3-in-5) inband loopdown code.
4 Have the CO tester send the NLOC (4-in-7) inband loopup for 5 seconds. Observe the NLOC message on the
front-panel display. The Status LED on the front panel should be yellow, and the loopback mode should also
be identified on the Monitor screen.
5 Repeat Step 2. If the test passes, the problem is in the downstream direction. If it fails, the problem is in the
upstream direction.
H2TU-C-202 List 3F
P
ROCEDURES
is a graphical representation of the various loopback configurations with the associated
Table 22 on page 52
Table 5 on page
for a description of these commands.
June 28, 2002
Testing
16. All equalizers should
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