Install DS1/T1 CPE loopback jack
Issue 10 June 2005 327
Testing the DS1 span from the ICSU to the loopback jack
The DS1 span test has 2 parts.
●Checking for circuit connectivity
The first part of the test powers-up the loopback jack and sends a signal from the DS1
circuit pack, through the wiring, to the loopback jack. The test allows about 10 seconds for
the signal to loop around the loopback jack and return to the DS1 circuit pack. Then it sends
the results to the management terminal and proceeds to the second part of the test.
●The second part of the test sends the standard, 3-in-24 DS1 stress- testing p attern from the
DS1 board, through the loopback jack, and back to a bit error detector and counter on the
DS1 board. A bit-error rate counter displays the results on the management terminal until
you terminates the test.
Always perform both parts of the test. Proceed as follows.

Checking the integrity of local equipment

Before you go any further, make sure that the problem is actually on the DS1 span by testing
the equipment that connects to the span at the near end. Test the DS1 circuit pack, and perform
any needed maintenance or repairs.

Busying out the DS1 circuit pack

Now take the DS1 circuit out of service.
1. Once you are sure that the DS1 circuit pack and ICSU are functioning correctly, go to the
management terminal and busy out the DS1 circuit pack by typing busyout board
UUCSS, where UU is the cabinet number, C is the carrier letter, and SS is the slot number of
the DS1 board.

Administering the DS1 for the test

1. At the management terminal, open the DS1 administration form. Type change ds1 UUCSS,
where UU is the cabinet number, C is the carrier letter, and SS is the slot number of the DS1
board.
2. Make sure that the near-end csu type field is set to integrated.
3. Change to page 2 of the DS1 administration form, and confirm that the value of the TX LBO
field is 0dB.
4. If the value of the TX LBO field is not 0dB, record the current value. Then set the TX LBO
field to 0dB for testing.
5. Press ENTER to make the changes, CANCEL to quit without changes.