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UDS1-BD (UDS1 Interface Circuit Pack)
Issue 5 October 2002
1787
555-233-119
Echo Cancellation
If the TN464GP/TN2464BP or later suffix UDS1 firmware detects a serious echo
canceller hardware error, it notifies maintenance software. When the maintenance
subsystem receives notification of the echo cancellation error, it executes this
Loss Of Signal Alarm Inquiry test.
This test, in addition to querying for a loss of signal condition and ICSU errors,
also queries the TN464GP/TN2464BP to confirm the echo canceller error. A
minor alarm is raised if the error is confirmed. The trunks of the board remain
in-service since the board is still functional except for the echo cancellation
capability.
If a loss of signal condition co-exists with ICSU and/or echo canceller errors, the
loss of signal condition takes priority, and the board and all trunks on the board
are put in the out-of-service state. Errors are logged, however, for each error type.
When the maintenance subsystem receives notification that the echo canceller
hardware error condition no longer exists, the maintenance subsystem restores
the board and all trunks to their previous service state, if the alarm can be cleared
(no other ICSU errors or loss of signal conditions exist).