Issue 1, Section 150-231-164
Revision 04
Page 9
5.09
To set the MARGIN ALARM THRESHOLD
select “G” from the SYSTEM SETTINGS MAIN
MENU Screen. Enter the desired minimum acceptable
alarm threshold from the 0 to 15 dB range. This causes
a minor alarm to occur (Section 4) if either the margin on
HDSL loop 1 (MAL1) or loop 2 (MAL2) drops
below the
selected threshold value. Since the margin can never
drop below 0, choosing “0” for the margin threshold turns
the margin alarm off.
5.10
Other system settings are set using a terminal in
a similar manner. Enter the key represented by
the letter in parenthesis of the parameter to be changed.
Each entry of this letter scrolls the parameter to its next
value. After all selections have been made, press E to
“Exit” and C to “Confirm” the changes. This activates
the new choices and returns control to the MAIN MENU
Screen.
5.11
The new T1 transceiver chip in the List 6D
allows the unit to process both B8ZS and AMI
code inputs, regardless of the DS1 code setting (AMI or
B8ZS). Earlier units caused input BPV, if B8ZS patterns
were processed while in the AMI mode. When the
newer units are in the AMI mode, they can receive B8ZS
but can only transmit AMI. For this reason, mixed
systems (those consisting of both List 6D and older List
1, 2, 3, 3A & 4) units will respond differently in each
direction for B8ZS inputs when in their AMI modes.
5.12
The SELF-TEST mode that occurs when both
HDSL loops are not in sync has been enhanced
to include the input DS1 transceiver chip in the self test
procedure. This process can cause the AIS pattern, that
is normally transmitted from the HLU-231 List 6D during
these out of sync intervals, to exhibit occasional BPVs.
5.13
The HAIS option provides two selections for the
T1 transmit outputs at both the HLU-231 List 6D
& HRU-412 for HDSL loss of sync conditions. The “1LP”
selection causes the AIS pattern to be transmitted at
both T1 outputs when either of the two HDSL loops
experience an out of sync (LOSW) condition or when a
margin alarm occurs. This choice causes the 12
channels on the surviving loop to be lost as they are
replaced by the AIS pattern. However it does allow both
down & upstream equipment to be made aware of the
loss of one HDSL loop or a loop with low margin. This is
the preferred setting to be able to initiate an AIS state
with just one conductor open in either of the HDSL pairs.
Short loops, below about 16 dB of loss at 200 kHz, can
remain in sync with one conductor open. Since the loop
is still in sync, no LOSW condition occurs. However, the
margin on a one conductor loop drops from 5 to 10 dB.
Thus if the Margin alarm is set to 5 dB below the normal
margin at turn-up, when one conductor does open, a
minor alarm occurs and causes the AIS condition. This
alerts the maintenance personnel of the problem. The
“2LP” choice requires both HDSL loops to be out of sync
(LOSW) before the AIS signal is transmitted. This
choice preserves the integrity of the 12 surviving
channels when just one loop is lost.
5.14
All user options that affect the operation in both
the HLU-231 List 6D & HRU-412, such as HAIS,
SAIS & DS0 blocking, are not available in older versions
of the HRU-412, List 1, 2, 3, 3A and 4, that do not
support these newer options.
5.15
The PairGain HCS-417 & 418 shelves and some
220-configuration shelves deployed in remote
cabinets do not have external equalizers. Therefore, the
EXT EQL option may not be used in these applications.
6. INSTALLATION
6.01
Upon receipt of the equipment, visually inspect it
for signs of damage. If the equipment has been
damaged in transit, immediately report the extent of
damage to the transportation company and to PairGain
Technologies.
6.02
The HLU-231 List 6D is designed to mount in a
220-configuration Office Repeater Bay (ORB)
shelf or equivalent Small Cross Section Shelf (SXSS),
Kentrox T-Term, Wescom 342-30 shelves, or PairGain
HLS-410 (19”) or HLS-419 (23”). The HLU-231 List 6D
slot pin-outs are shown in Figure 4.
6.03
The ALM option must be disabled (DIS) when
using the Kentrox 220 T-Term shelf. This is
required to resolve a conflict between the HLU alarm
relay output and the Kentrox external equalizer output.
Both use the same pins, 20 and 21.
6.04.
The HLU-231, LCD and all other HiGain HLU-
231 line units built to date are incompatible with
the newer Kentrox 224 shelves when these shelves are
optioned to connect their -V line (which is normally -48 V
to -130 V). The -V line connects to pin 40, while the
HLU-231 connects both pins 39 and 40 to the -48 V line.
