Loopback Operation - ADC HiGain HLU-200 User Manual

150-200-114-03, Issue 03

Loopback Operation

The HiGain system has a family of loopback options. The most important of these is the SmartJack loopback
which enables the HRU-412 to respond to the standard (2/3-in-5) SmartJack inband loopback codes. This
option can be enabled or disabled from the terminal SYSTEM SETTINGS Menu Screen (Figure 12).
In addition to the SmartJack loopback, the HiGain system can be configured for one of five special
inband loopback (SPLB) command sequences. These are selected from the SPLB user options shown in Table
10. The loopback locations are shown in Figure 8.
GNLB is the HiGain system Generic loopback code. The GNLB allows inband codes issued to the HLU from
the CBA to loop-up either the HLU/NLOC (4-in-7) or HRU/ NREM (3-in-7) towards the CBA. In addition, it
allows inband codes from the Customer Interface (CI) to loop-up the HLU/CREM ( 6-in-7 ) or HRU/CLOC
(5-in-7) towards the customer. For Doubler applications it permits looping Doubler #1 towards the network
NDU1 ( 2-in-6 ) or towards the customer CDU1
( 4-in-6 ). Doubler #2 is looped towards the network with NDU2 (3-in-6) or towards the customer with CDU2
( 5-in-6 ). Either loop-up condition is terminated (looped-down) with the ( 3-in-5 ) loop-down code. All
messages must be present for five seconds before the HiGain system will respond. Table 19 lists the test
procedures that apply when using the GNLB mode.
The A1LB loopback selection, Table 12 complies with that proposed for HDSL systems in the
T1/E-1.4/92 recommendation with the following additions:
•
Query loopback
•
IOR power-down
•
Three loopback time-out choices
•
Initiation from either end
•
Repeating bit error signatures
•
Alternate query loopback.
These additions make A1LB identical to the 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 inband loopback functions that are supported by the
HLU-200 List 1D HiGain system. These loopbacks provide the HiGain system with sophisticated maintenance
and troubleshooting tools. Tables 13 through 16 list the details of these SPLB functions. A2LB and A5LB are
patterned 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 1D into
the network. A2LB can be configured to either block this arming code after two seconds, and replace it with
HLU-200 List 1D November 22, 1996 27