Loopback Test Procedures; General Troubleshooting Tips; Gnlb Test Procedures - ADC PAIRGAIN HiGain HDSL2 Manual

Testing
You can terminate loopbacks manually and exit the MAN LPBK mode by simultaneously pressing the MODE and
SEL buttons for 3 or more seconds. If no loopback is active, the MAN LPBK mode automatically terminates after
30 seconds.
All loopbacks can be initiated by inband commands in the DS1 payload or by a command from the HiGain HDSL2
system (front-panel buttons 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
HiGain HDSL2 system.
SMJK loopback commands are only activated by inband commands.
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 interface 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.
The transmit and receive DS1 DSX-1 ports have splitting access jacks and miniature, 210-series, bridging jacks
as shown in Figure 2 on page
two SPAN jacks splits the IN and OUT and creates metallic loopbacks towards both the DSX-1 and the
H2TU-C-231. If separate plugs are inserted into both SPAN jacks with the other end disconnected, the BRG jacks
can be used to send and receive test patterns towards the DSX-1.

GNLB Test Procedures

Figure 26 on page 53
GNLB commands shown. Also, refer to
To perform the GNLB loopback test procedure:
1 Have the CO tester send the NREM (3-in-7) inband loopup code for 5 seconds. You should be able to 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 Span Status screen.)
2 Have the CO tester transmit a DS1 test signal towards 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. You should be able to 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 Span Status 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.
52
P
ROCEDURES
4. Connecting one cable between the two bridging jacks and another between the
is a graphical representation of the various loopback configurations with the associated
Table 21 on page 49
Table 6 on page
for a description of these commands.
April 21, 2000
152-231-115-03, Revision 03
21. All equalizers should
H2TU-C-231 List 1E