ADTRAN 1202060L2-1, User Manual

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Chapter 1. Introduction
1-8 TSU LT User Manual 1202060L2-1
TSU LT Testing
The TSU LT offers three forms of testing:
• Self-test
• Loopback tests
• Pattern generation and check
Self-test
The self-test checks the integrity of the internal operation of
the electronic components by performing memory tests and
by sending and verifying data test patterns through all
internal interfaces. Although actual user data cannot be
passed during these tests, the self-test can run with the
network and DTE interfaces in place and without disturbing
any external interface.
The self-test automatically executes upon power up. It can
also be commanded from a front panel menu or from the
control port.
In addition to the specified self-tests, background tests are
also run on various parts of the internal electronics. These
run during normal operation to confirm continued correct
functioning. The background tests include:
• Monitoring the phase-locked loop for lock.
• Standard background network performance monitoring,
as required by ANSI T1.403 and AT&T 54016 for which
the results are stored.
Loopback Tests
A number of different loopbacks can be invoked locally from
the front panel, by T-Watch commands, or remotely by using
special inband codes. These include AT&T D4 network loop
up/loop down codes and V.54 loop up/loop down codes for
the Nx56K/64K serial interface. Additionally the loopbacks
can be remotely controlled by out-of-band commands via the
T1 ESF facility data link (FDL), or from T-Watch via a modem