ADC HiGain HLU-200 List 2D User Manual page 38

Loopback Operation
The A1LB loopback selection complies with that proposed for HDSL systems in the T1E1.4/92 recommendation
with the following additions:
•
Query loopback
•
IOR (Intelligent Office Repeater) power-down
•
Three loopback time-out choices
•
Initiation from either end
•
Repeating bit error signatures
•
Alternate query loopback
These additions make A1LB identical to A2LB described below. It is given a separate identity to allow future
T1/E1 enhancements to be added without affecting A2LB.
A2LB through A5LB are four special addressable repeater in-band loopback functions which are supported by the
HLU-200 HiGain system. These loopbacks provide the HiGain system with sophisticated maintenance and
trouble shooting tools. Tables
after the Teltrend addressable T1 repeater loopbacks. A3LB and A4LB are patterned after the Wescom
addressable T1 repeater loopbacks. All four SPLBs have been enhanced to handle the specific requirements of the
following HiGain system customers:
•
A2LB (Teltrend) = Southwestern Bell
•
A3LB (Wescom) = New England Telephone
•
A4LB (Wescom Mod 1) = New York Telephone
•
A5LB (Teltrend Mod 1) = Southern New England Telephone (SNET)
A5LB differs from A2LB in that A5LB does not block the arming code from exiting the HLU-200 List 2D toward
the CBA. A2LB can be configured to either block this arming code after two seconds, and replace it with the AIS
code, or to unblock it by executing the FAR-END ACTIVATE code. Since A5LB never blocks the arming code
from exiting the HLU-200 List 2D, it does not support this FAR-END ACTIVATE code. A3LB differs from
A4LB in that A3LB supports the additional (1 in 6) SmartJack loopback command.
The green Loop LED on the HLU front panel lights whenever any of the circuit modules (HLU, HDU or HRU)
is in a loopback state.
Although the following loopback section describes, HLU, HRU and HDU (doubler) loopbacks
commands, the HLU-200, List 2D when managed by the current version of Litecraft, does not
support doubler applications.
28
10 and 11 list the details of these SPLB functions. A2LB and A5LB are patterned
February 10, 1999
150-200-124-02, Issue 2
HLU-200 List 2D