Provisioning
150-432-100-02, Revision 02
22
July 18, 2002
HLU-432 List 1
Equalization Option
Equalization is the configuration of system transmission characteristics within specified limits. An adaptive
equalizer inserts a frequency-shaped loss that corresponds to an equivalent addition of an appropriate cable length.
By simulating the additional cable loss necessary for correct operation, the equalizer compensates for a range of
variation in transmission path characteristics.
BPVT Option
The HLU-432 improves HiGain’s compatibility with Digital Loop Carrier (DLC) feeder applications because of
its ability to transmit T1 BPV occurrences between its T1 interfaces. This feature is required to support protection
switching in DLC applications. Each DLC terminal must be able to monitor the integrity of its Receive T1 payload
and then switch to the protected line when the integrity of the path drops below specific user-selected limits. An
essential requirement of this feature is the need for each DLC terminal to detect BPVs in its T1 input. Standard
HDSL systems correct T1 BPVs at the input and thus prevent them from being detected by the DLC terminals to
which they are connected. The HLU-432 and its associated remote units remove this limitation and become BPV
transparent by detecting and counting input BPVs at each end and then replicating them at the T1 output port of
the distant end.
This BPVT option is controlled by the BPVT user option, which allows it to be Enabled (ENA) or Disabled (DIS).
In addition, the CRCs in each direction of every HDSL loop of each span are also counted and added in with the
BPV count to produce a Total Error Count (TEC) that indicates the integrity of both the T1 and HDSL paths. A
TEC in each direction is calculated each second by adding the number of BPVs to the number of HDSL CRCs in
that direction. The maximum TEC number is 12000. This TEC number is converted into BPVs at the distant end
during the following second at a rate of 1 BPV every 128 T1 bits up to a maximum of 12000 (BER = 7.7 x 10
-3
).
This maximum rate is more than adequate since it exceeds the maximum 10
-3
BER required by most DLC systems.
BER Option
The BER option also uses this (BPV/CRC) TEC to generate an Alarm if enabled. The HLU combines the 1-second
TEC counts in both directions for the last 60 seconds. It uses this one-minute Total System Error Count (TSEC)
to generate an alarm if it exceeds the selected BER threshold of (1E-6 or 1E-7) as follows:
•
BER option = 1E-6. Alarm is generated if TSEC > 92
Bipolar Violation
Transparency
(See
below.)
BPVT
ENA
Enables BPVs and HDSL CRC errors at the T1 input to be converted into T1
BPVs at the distant end’s T1 output. This makes HiGain transparent to BPVs.
DIS
Disables BPVT.
Confirm Settings
C
Confirms that all operating modes are to be updated to their current
selections.
Any other
key
Prevents the most recently selected operating mode selections from being
updated. They remain as they were before the system option settings mode
was entered.
When BPVT is enabled in systems with four or less doublers, the response time to an HDSL
LOSW is approximately 70 ms, which gives DLC terminals time to react and avoid dropped calls.
Table 8.
HLU-432 List 1 System Settings (Cont.)
System Settings
Screen Options
Front-Panel
Display
Code
Parameter
Description
