ADTRAN HDSL2 - Manual (Page 81)

HDSL2 for General Distribution Installation and Maintenance Practice HDSL New Enhanced Feature Overview
61223HDSL2L2-5B B-9
Event History Screen
The Event History screen (
Figure B-5 ) shows the messages reported in the event log due to the
splice detector. Any reset of the detector is shown as well as the first detect seen since the last
reset.
Figure B-5. Event History Screen
Fault (GFI, Short) Bridging
The Fault Bridging feature minimizes circuit downtime by sustaining the circuit during the
impairment until good signal returns, thereby preventing a retrain. Downtime can occur when
an intermittent impairment (GFI, short, micro-interruption, bad splice, noise burst, etc.)
briefly affects the HDSL loop.
Fault bridging addresses two general types of problems:
• Brief power fault incidents (lightning)
• Brief signal distortions
In the older generation HDSL2 and HDSL4 transceivers, a brief short or GFI would cause a
hardware control to quickly shut down the span power supply for safety reasons. The software
would then detect the power fault and would hold the span supply off for 3 seconds. The
HDSL units would then reinitialize and retrain in approximately 25 to 30 seconds.
In the new enhanced units a combination of hardware and software enhancements allows the
units to sustain communication during brief interruptions in the span supply or brief distor-
tions of the HDSL signal. The hardware will still react to shut down the span supply for the
duration of a power fault to comply with safety requirements; however, the software will wait
much longer (150 msec of fault) before holding the span supply off. This will allow the span
power to return immediately if the power fault disappears. The hardware contains extra
capacitance to help maintain the power supply voltages during this brief interruption of span
Circuit ID: Chronic Circuit 01/09/05 13:31:36
Press ESC to return to previous menu
Num Description of Event Date Time Source
------------------------------------------------------------------------------
1. H2TU-C Event Log Reset 01/09/05 13:34:36 H2TU-C
2. H2TU-C Powered Up 01/09/05 13:30:01 H2TU-C
3. H2TU-R Powered Up 01/09/05 13:30:15 NO ID
4. Splice Detector Reset 01/09/05 13:30:29 H2TU-R
5. Bad Splice Detected 01/09/05 17:30:33 NO ID
Page Number: 1/ 1 Number of Events: 5
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