150-388-151-01, Revision 01
Provisioning
HLU-388 List 5A
September 15, 1999
25
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-388 List 5A 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 therefore prevent them from being detected by the DLC
terminals to which they are connected. The HLU-388 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. When the BPVT option is Enabled (ENA), the Fast LOSW feature reports LOSW
conditions within approximately 2 seconds. When the BPVT option is Disabled (DIS), LOSW conditions may
take up to 10 seconds.
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 count 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.
Bipolar Violation
Transparency
(See
below.)
BPVT
ENA
Enables BPVs and HDSL CRC errors at the DS1 input to be converted into DS1
BPVs at the distant end’s DS1 output. This makes HiGain transparent to BPVs.
Enabling this option also enables the Fast LOSW feature (see the note below).
DIS
Inhibits reporting of BVPs and CRC errors at the DS1 input and disables the
Fast LOSW reporting function.
Confirm Settings
CONF
YES
Confirms that all operating modes are to be updated to their current
selections.
NO
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 fewer doublers, the response time to an HDSL
LOSW is reduced to approximately 70 (milliseconds) ms, which gives DLC terminals time to
react and avoid dropped calls. This is known as the “Fast LOSW” feature.
Table 9.
HLU-388 List 5A System Settings (Cont.)
System Settings
Screen Options
Front-panel
Display
Code
Parameter
Description
