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Bad Splice Detection (TScan)
The SHDSL 2-Wire/4-Wire LTU provides bad splice protection using the ADTRAN proprietary
™
Runtime TScan
2.0 splice protection feature. TScan splice detection is a non-intrusive
algorithm that enables the SHDSL 2-Wire/4-Wire LTU to detect anomalies (bad splices) in the
copper pair. This feature can aid in troubleshooting the distribution plant.
Data transmission transceivers (especially echo-cancelled technologies) are subject to perfor-
mance degradations and errors in the presence of bad splice connections. A splice may be
benign for a period of time, allowing a circuit to behave appropriately for portions of the day.
Over time the splice can oxidize and incur small, rapid changes in impedance. This inconsis-
tency in behavior makes the problem difficult to locate. Additionally, an impedance change
that is large enough to cause the transceiver trouble may still be small enough to be
undetected by test equipment used on the copper pairs.
The splice detection algorithm is designed to detect bad splices in data mode. The detector
runs periodically after a SHDSL 2-Wire/4-Wire LTU achieves synchronization. The SHDSL
transceiver monitors the loop for impedance changes that are of a magnitude to degrade the
received signal of the transceiver. When the transceiver detects a significant impedance
change, the approximate distance from that transceiver to the anomaly is recorded on a menu
screen, the Bad Splice Detection (TSCAN) 24 Hour Counts menu screen, by incrementing the
appropriate counter. When enough counts are accumulated at a particular distance, this
distance is reported on the Bad Splice Detection (TSCAN) menu screen.
The Splice Detection Feature is included with this product as an
aid to troubleshooting. Due to inconsistency in environmental
conditions and their effect on telecommunications plant, ADTRAN
cannot guarantee the accuracy of the measurements. Comparison
to existing engineering drawings should provide exact locations of
suspect splices indicated by ADTRAN algorithms.
Managing TScan
The VT100 local management port allows access to the splice detection menus through the
selection from the Main Menu (refer to
TSCAN
LTU Main Menus provide access to the module. The Main Menu options have several
functions and submenus that identify and provide access to specific operations and param-
eters.
Bad Splice Detection (TSCAN) Menu
The Bad Splice Detection (TSCAN) menu displays a summary of the bad splice results (see
Figure
10).
• If a SHDSL loop is in good condition, a "No Trouble Found" status appears in the results
column.
• If a count register exceeds a certain threshold, a bad splice is predicted to exist at this
distance and displays in the results column.
61230011L1-5B
NOTE
Figure 7
on page 15). The SHDSL 2-Wire/4-Wire
Troubleshooting
21
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