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DS1 Network
Interface Loopback
with Self-Test
EQUIPMENT
LOCAL CSU
TPG = TEST PATTERN GENERATOR
FIGURE 4-9. DS1 NETWORK INTERFACE LOOPBACK WITH SELF-TEST
DS1 Network Interface Loopback with Self-Test, illustrated in Figure 4-9,
tests the local CSU and the T1 link by transmitting a local CSU-generated
test pattern to the remote DS1 Interface Connector and looping it back for
verification. The test pattern is selected via the Supervisory terminal.
Within the local CSU, a Test Pattern Generator creates the test pattern,
and a Test Pattern Recognizer determines if the data it receives matches
that which was transmitted. Whether the local CSU transmits framed or
unframed loopback codes depends on the selection of the loopback test code
framing option.
When connected to a DS1 Interface Connector, the
DataComm 551 must be configured for manual Line
Build-Out, with 0 dB attenuation.
This test can only be controlled locally via the Supervisory terminal NI
Loop test and Self-Test. To perform this test, refer to Table 4-5.
TABLE 4-5. DS1 NETWORK INTERFACE LOOPBACK WITH
Step
1.
To prevent data loss, suspend operation of all associated digital-terminating
equipment.
2.
Initiate NI Loop at the local CSU (on the LOOPBACKS screen), and then select
the desired test pattern and initiate Self-Test (on the SELF TEST screen). The
front panel TM indicator should light and the status line ST indicator should
come on.
3.
Monitor Test Results for the averaged BER. A high BER indicates that a
problem exists.
4.
To stop the test, terminate Self-Test and then NI Loop.
TPR
TPG
CAUTION
SELF-TEST
Supervisory Terminal Control
T1
NETWORK
DS1 INTERFACE
CONNECTOR
TPR = TEST PATTERN RECOGNIZER
TESTS
EQUIPMENT
REMOTE CSU
4-11
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