ADC H2TU-C-319 List 4E IN-BAND LOOPBACK SESSIONS

LTPH-UM-1049-02, Issue 2 Testing

H2TU-C-319 List 4E January 9, 2002 59

You can also manually terminate the MTA state and exit the MAN LPBK mode by simultaneously pressing the

MODE and LBK pushbuttons for 3 or more seconds. If no loopback or MTA is active, the MAN LPBK mode

automatically terminates after 30 seconds.

IN-BAND LOOPBACK SESSIONS

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.

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 shelf connector.

•H2TU-C internal equalizer is set to the correct distance range, as shown in Table5 on page 18. All equalizers

should be set to the distance from the DSX-1 to the shelf.

The transmit and receive DSX-1 ports have splitting access jacks and miniature, 210-series, bridging jacks as

shown in Figure 1 on page3. Connecting one cable between the two bridging jacks and another between the two

LINE jacks splits the IN and OUT and creates metallic loopbacks toward both the DSX-1 and the H2TU-C. If

separate plugs are inserted into both LINE jacks with the other end disconnected, the BRG jacks can be used to

send and receive test patterns toward the DSX-1. The AUX DSX-1 port has no resident test jack access.

Figure32 on page 60 is a graphical representation of the various loopback configurations with the associated

GNLB commands shown. Table 22 on page56 for a description of these commands.

To perform the GNLB loopback test procedure:

1Have the CO tester send the NREM (3-in-7) in-band 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 Monitor screen.

2Have 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.

3If Step2 fails , have the CO tester transmit the (3-in-5) in-band loopdown code.

4Have the CO tester send the NLOC (4-in-7) in-band 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 Monitor screen.

5Repeat Step 2. If the test passes, the problem is in the downstream direction. If it fails, the problem is in the

upstream direction.

The equalizer settings only apply to the specific DSX-1 port selected by the ADS1 option, MUX

or AUX. The unselected port defaults to an equalizer setting of zero.