PairGain HiGain HLU-D41 User manual

HIGAIN LINE UNIT
Model List Number Part Number CLEI Code
HLU-D41 2D 150-1260-24 T1L2BE0AAA
PAIRGAIN TECHNOLOGIES, INC.
ENGINEERING SERVICES TECHNICAL PRACTICE
SECTION 150-441-124-01
Revision History of this practice.
June 12, 1997
A) Initial Release

Section 150-441-124 June 12, 1997 Revision 01
Page ii PairGain Engineering - Plant Series HiGain HLU-D41
TABLE OF CONTENTS
A. PRODUCT OVERVIEW................................................................................................................1
1. Description and Features....................................................................................................1
2. Specifications....................................................................................................................3
3. Applications ......................................................................................................................4
4. Functional Operation.........................................................................................................5
5. Power Consumption and Powering the Remote Unit..........................................................6
6. Alarms...............................................................................................................................7
B. INSTALLATION.............................................................................................................................8
7. Inspecting Your Shipment .................................................................................................8
8. HLU-D41 Card Edge Pin-Out Diagram .............................................................................9
9. Installing the HLU-D41....................................................................................................12
10. Connecting to a Dumb Terminal.....................................................................................13
11. Initialization ...................................................................................................................14
C. SETTING OPTIONS FROM THE FRONT PANEL ...................................................................15
12. Using the Mode and Choice Setup Buttons .....................................................................15
13. Mandatory System Options.............................................................................................19
D. SETTING OPTIONS FROM THE MAINTENANCE TERMINAL............................................21
14. Using the Maintenance Terminal Menus.........................................................................21
15. Maintenance Terminal Main Menu.................................................................................22
16. View Span Status............................................................................................................23
17. Set Clock........................................................................................................................26
18. System Settings ..............................................................................................................27
19. Loopback Mode..............................................................................................................30
20. View Performance Data..................................................................................................33
21. View Performance History..............................................................................................34
22. Alarm History.................................................................................................................35
23. Enter Circuit ID..............................................................................................................36
E. TROUBLESHOOTING.................................................................................................................37
24. Loopbacks Issued from the Front Panel...........................................................................37
25. Digital Data Service (DDS) NEI Test Access and Control ..............................................40
F. PRODUCT SUPPORT...................................................................................................................41
26. Technical Support...........................................................................................................41
27. PairGain Warranty..........................................................................................................41
28. Certification....................................................................................................................41
G. ABBREVIATIONS AND GLOSSARY .........................................................................................42
29. Abbreviations and Glossary ............................................................................................42

Revision 01 June 12, 1997 Section 150-441-124
HiGain HLU-D41 PairGain Engineering - Plant Series Page iii
USING THIS TECHNICAL PRACTICE
The following conventions are used in this practice:

Keys that are pressed on the keyboard are enclosed in brackets.
Press the <Enter> key.

Options selected using the front panel Mode and Choice Setup buttons and the Maintenance Terminal
menus are italicized.
The Network Loopback option can be set to Enable or Disable.

Fields are identified with quote marks.
Table 14 lists the "Alarm" messages and descriptions.
Three types of messages, identified by icons, appear in the text:
A note informs you of special circumstances.
A caution indicates the possibility of equipment damage.
A warning indicates the possibility of personal injury.

Copyright 1997 PairGain Technologies, Inc.
PairGain is a registered trademark, and HiGain is a trademark of PairGain Technologies, Inc.

Revision 01 June 12, 1997 Section 150-441-124
HiGain HLU-D41 PairGain Engineering - Plant Series Page 1
A. PRODUCT OVERVIEW
1. Description and Features
1.1 This technical practice describes the PairGain
®
HiGain  HLU-D41 List 2D, a HiGain Line Unit
(HLU) which functions as the Central Office (CO) side of a repeater-less Fractional T1 (FT1)
transmission system. The HLU-D41 can be plugged into a channel unit slot of a D4 channel bank or
an SLC-96 channel bank. This practice describes using the HLU-D41 with and without HiGain
Doubler Units (HDUs). The software version number for this release is 2.3.
1.2 Figure 1 shows a basic HiGain configuration for an FT1 Single-pair High-bit-rate Digital Subscriber
Line (S-HDSL) circuit. The HLU-D41 is installed at the CO channel bank and the HRU-512 is
housed in a remote enclosure at the Customer Premises Equipment (CPE) site. The optional
HDU-217 or HDU-219 installed in a doubler enclosure provides the ability to double or even triple
the transmission distance range for customer applications located outside the Carrier Service Area
(CSA). The CSA includes loops up to 12000 feet of AWG 24 or 9000 feet of AWG 26 wire,
including bridged taps.
Figure 1. Typical HiGain S-HDSL System
1.3 HLU-D41 List 2D features

Selectable payload bandwidth from 64 kbps (one channel) to 768 kbps (12 channels) in 64 kbps
increments over the full CSA

Front panel:
– DS1 splitting and bridging access
– Status LEDs and user option setup buttons
– LCD display of HDSL margin, configuration parameters, and alarms

Automatic front panel display power saving timer

RS-232 connector for setting options from the Maintenance Terminal

Responds to Digital Data Service (DDS), Network Element Interface (NEI), and Office Channel
Unit (OCU) loopback codes

Provisionable idle code (7F or FF) on unused channels

Lightning and power cross protection on S-HDSL interface

200V power feed can line power two spans (one doubler and one remote, or two doublers and a
locally-powered remote)

Section 150-441-124 June 12, 1997 Revision 01
Page 2 PairGain Engineering - Plant Series HiGain HLU-D41
1.4 Front Panel. Figure 2 and Table 1 describe the HLU-D41 front panel. The four-digit LCD and the
status LEDs indicate different system states.
Figure 2. HLU-D41 Front Panel
Table 1. HLU-D41 Front Panel Components
Name Function
Four-digit LCD Shows HDSL conditions, s
y
stem o
p
tions, messa
g
es and alarm states (see Section 12).
Alarm messages are listed in Section 6.
Mode and Choice Setu
p
buttons Set system options (see Section 12).
DDS test access jacks Bantam jacks designated as Logic Out and Logic In for high-speed DDS test access.
Status LED Indicates status, warnings, and alarm conditions (see Table 2).
RS-232 connector Confi
g
ured as Data Circuit-Terminatin
g
E
q
ui
p
ment (DCE) which allows
y
ou to control
the HLU-D41 through a dumb terminal (or a PC with terminal emulation software).
Retaining latch Latch used to retain the HLU-D41 in the channel bank.

Revision 01 June 12, 1997 Section 150-441-124
HiGain HLU-D41 PairGain Engineering - Plant Series Page 3
Table 2. Status LED Messages
Color Definition
Green Normal operation
Flashing Green HDSL acquisition
Red Fuse Alarm
Flashing Red Minor alarm (For conditions see Section 6.1, Table 5).
Yellow Self-test in
p
rocess or a Customer Remote (CREM) or
Network Local (NLOC) loopback is in effect.
2. Specifications
S-HDSL
Line Code ..........................................................768 kbps 2B1Q
Output................................................................+13.5 dB ±0.5 dB at 135 ohms
Line Impedance .................................................135 ohms
Start-up Time.....................................................30 seconds (typical), 60 seconds (maximum) per span
Span Voltage......................................................-200 Vdc
Compliance........................................................TA-TSY-001210
Maximum Provisioning Loss
35 dB at 196 kHz, 135 ohms
Line Clock Rate
Internal Stratum 4 clock
Maximum Power Consumption
Without doubler.................................................10 W
With doubler......................................................14 W
Maximum Heat Dissipation
Without doubler.................................................3 W
With doubler......................................................6 W
Electrical Protection
Secondary surge protection on DS1 and HDSL ports. Power cross protection on HDSL ports.
Environmental
Operating Temperature ......................................-40°to +149°F (-40°to +65°C)
Operating Humidity ...........................................5 to 95% (non-condensing)
Mounting
Single channel unit slot of a D4 or SLC-96 channel bank.
DS1Line Rate ...........................................................1.544 Mbps ±200 bps
Line Format .......................................................AMI, B8ZS or ZBTSI
Frame Format.....................................................ESF or SF

Section 150-441-124 June 12, 1997 Revision 01
Page 4 PairGain Engineering - Plant Series HiGain HLU-D41
Dimensions
Height................................................................4.5-inch (11.4 cm)
Width ................................................................1.4-inch (3.6 cm)
Depth.................................................................10.1-inch (25.7 cm)
Weight...............................................................0.7 lb. (.32 kg)
Margin Indicator
Displays HDSL span Signal-to-Noise Ratio (SNR) margin relative to 10-7 Bit Error Ratio (BER) operation
3. Applications
3.1 This HiGain system provides a cost-effective, easy-to-deploy method for delivering FT1 service over
a single metallic pair. Conventional in-line T1 repeaters are not required. Cable pair conditioning,
pair separation and bridged tap removal are not required.
3.2 General guidelines require that the loop has less than 35 dB of loss at 196 kHz, with 135 ohms
driving and terminating impedances. Table 3 provides a guide for the loss of various cable gauges at
196 kHz and 135 ohms. The table applies to the HDSL cable pairs between the HLU, HRU and
HDU modules. Without specific insertion loss measurement data, add 3 dB for each bridged tap and
1 dB for each cable gauge change.
Table 3. HDSL Loss Over Cables
Cable Gauge Loss at 196 kHz
(dB/kft) Ohms per kft
26/0.4 mm 3.88 83
24/0.51 mm 2.84 52
22/0.61 mm 2.18 32
19/0.91 mm 1.54 16
3.3 HiGain systems:

Operate with any number of other T1, Plain Old Telephone Service (POTS), DDS or other
HiGain systems sharing the same cable binder group.

Can be used with customers requiring FT1 service on a temporary or permanent basis.

Provide a means of quickly deploying service in advance of fiber-optic transmission systems.

Are easily installed allowing service to be provided within hours. Fiber optic systems can be
installed at a leisurely pace and cut-over from the installed HiGain system when convenient to
do so. The installed HiGain system can then be easily removed and utilized elsewhere.

Revision 01 June 12, 1997 Section 150-441-124
HiGain HLU-D41 PairGain Engineering - Plant Series Page 5
4. Functional Operation
4.1 The HLU-D41 block diagram is shown in Figure 3.
Figure 3. HLU-D41 Block Diagram
The HLU-D41 uses one PairGain Technologies 2B1Q HDSL transceiver to establish a full duplex
784 kbps data link to the remote unit in the following sequence:
1Multiplexed DS0 channels are extracted from the channel bank backplane. The number of
channels extracted is determined by the BAND option setting using the front panel Mode and
Choice Setup buttons, or the DS0 BANDWIDTH option using the Maintenance Terminal menus.
2The DS0 channels optioned for A/B Robbed Bit Signaling (RBS) are properly formatted, then
the DS0 channels are passed to the DS1 formatter which builds a DS1 signal.
3The formatter inserts DS1 framing information and generates the Idle Code (7F or FF) to
complete a 12 DS0 payload for the half-DS1 signal, then the half-DS1 signal is passed to the
HDSL framer.
4The framer bit stuffs the half-DS1 signal into the HDSL payload envelope and adds the required
HDSL overhead.
5The 784 kbps HDSL signal is encoded by the single pair transceiver into a 2B1Q signal.
6The 2B1Q signal is coupled to the twisted pair line by a transformer in the line interface, which
allows the line interface to provide lightning and power cross protection.
7The 784 kbps signal from the remote HDSL transceiver is received by the HDSL line interface.
8The single pair transceiver does a two-wire to four-wire conversion of the signal using echo-
canceling technology, then the signal to be transmitted toward the channel bank is processed by
the HDSL framer which monitors its signal quality.
9Detected errors are reported to the micro-processor, the payload is extracted, and up to 12 DS0
channels are transmitted to the channel bank, with the DS1 formatter locating the first DS0 in

Section 150-441-124 June 12, 1997 Revision 01
Page 6 PairGain Engineering - Plant Series HiGain HLU-D41
the payload. An 8-bit microprocessor is used to monitor and control the HLU-D41.
Provisioning status information is provided either through the HLU-D41 Maintenance Terminal
menus or the front panel Mode and Choice Setup buttons, to the microprocessor. The micro-
processor communicates with the HDSL framer for signal status and configures the circuit
bandwidth at the DS0 channel interface.
5. Power Consumption and Powering the Remote Unit
5.1 The primary power demands of an HLU-D41 on the channel bank power supply are listed in Table 4
on a per slot basis.
Table 4. Power Consumption and Power Dissipation
Power* Per Slot
Maximum Power Consumption
Line-powered remote unit 14 W
Locally-powered remote unit 10 W
Maximum Power Dissipation
Line-powered remote unit 6 W
Locally-powered remote unit 3 W
The worst case conditions under which these parameters are
measured include a 9,000 ft., 26 AWG loop configuration.
5.2 The maximum number of channel bank slots that can be occupied by HLU-D41 units is a function of
the type of bank and the capabilities of its common power supply. The limiting factor is the drain on
the bank’s +5V power supply. The HLU-D41 draws 295mA of +5V power when the HRU is locally
powered and 325mA when the HRU is line powered. The worst case +5V current drain for D4
common equipment is 1.2A.
5.3 Line and Local Powering of the Remote Unit. The HLU-D41 is designed to either power the
HRU-512 over the HDSL cable pair, or allow the HRU-512 to be powered from the remote end. The
HLU-D41 determines the power state of the HRU-512 before attempting to apply line power:

If the HRU-512 is remotely powered, the HLU-D41 does not apply line power.

If the HRU-512 is not remotely powered, the HLU-D41 applies power to the HRU-512 over the
HDSL cable pair.
The line power supply can be turned on or off by using the PWRF (power feed) system option setting
and is automatically shut down in the presence of line short circuits or a microprocessor failure.
The HRU-512 also provides from 14 mA (long loop) to 16 mA (short loop) of metallic sealing
current toward the HLU-D41, when the HRU-512 is locally powered. To enable the sealing current
capability when the HRU-512 is locally powered, connect JP2 across both terminals.
To configure the system for HLU-D41 line powering
1At the HRU-512, connect JP2 across just one of the two terminals. These are the factory default
settings.
2Enable the PWRF option setting using the front panel setup buttons, or the Maintenance
Terminal menus using the POWER option in the System Settings menu.

Revision 01 June 12, 1997 Section 150-441-124
HiGain HLU-D41 PairGain Engineering - Plant Series Page 7
See the PairGain Technologies HiGain-1 FT1 Remote Unit, Model HRU-512, Issue 1 Technical
Practice (Part No. 150-512-100-02) for further information.
5.4 Power Conversion. The HLU-D41 contains two separate power converters. The linear regulator
converts the D4 channel bank dc power (+5 Vdc and -12 Vdc) to logic power for the HLU-D41
circuits. The line power supply converts the D4 channel bank dc power (-48 Vdc) to a -200 Vdc feed
to power the HRU-512.
5.5 A Pulsecom 325A Power Converter, or equivalent, supplies 5A at +5V, allowing up to 11 HLU-D41
units per D4 channel bank.
The 325A D4 channel bank power converter supplies 3A at +5V. That leaves 1.8A for the 48
channel slots or 37mA per slot. This translates to 1.8/.325A or a maximum of five (5) HLU-D41
units per D4 channel bank (two to three units per digroup).
The PCU SLC-96 power converter supplies 3.2A at +5V. This leaves 2A for the 48 dual channel
slots, which translates to 2/.325 or a maximum of six (6) HLU-D41 units per SLC-96 channel bank.
If the enhanced PCU 325A converter, which supplies 5A is used, a maximum of 12 HLU-D41 units
per SLC-96 channel bank can be used. Apply these same rules to calculate the maximum number of
HLU units per channel bank for channel bank power supplies with different capacities.
5.6 Front Panel LCD Power Saving Timer. The four-digit front panel LCD is activated when
power is initially applied to the line unit. To conserve power, the display remains active for only
four minutes if neither the Mode or Choice setup buttons are pressed. The use of either button re-
activates the four-digit display and restarts the four minute power saving timer.
6. Alarms
6.1 Front-Panel Alarm Displays. The HLU-D41 Status LED flashes red for the duration of a minor
alarm condition. Table 5 lists the HLU-D41 alarms that can be displayed in the front-panel LCD
(these alarm conditions display in the "Alarms" field of the View Span Status screen as well). The
message "ALRM" appears one time in the front panel LCD prior to the display of the alarm
condition message.

The front panel message that accompanies each alarm condition is listed in the "Alarm" column.

Since more than one alarm condition can exist at any time, but only one message can be
displayed, only the highest priority alarm is displayed if more than one alarm condition exists.

The alarms are listed in their order of priority.
Table 5. Alarm Conditions
Alarm Reason
LOSW The HDSL loop has lost sync.
MOOS The channel bank is out of sync.
RLOS Loss of HRU-512 DS1 input signal.
HES The HDSL Loo
p
has exceeded the 24 hour user-selected Errored-Seconds C
y
clic
Redundanc
y
Check (CRC) threshold (set at front
p
anel usin
g
the ESAL o
p
tion or at the
System Settings menu using ES ALARM THRES).
DS1 The total number of Bi
p
olar Violations (BPV) at the HRU-512 DS1 in
p
ut has
exceeded the 24-hour user-selected threshold (set at the front
p
anel usin
g
the DS1
option or at the System Settings menu using DS1 LINE CODE).
MAL The mar
g
in on the HDSL Loo
p
has dro
pp
ed below the minimum threshold value set
using the Margin Alarm Threshold option as described in Section 18.12.

Section 150-441-124 June 12, 1997 Revision 01
Page 8 PairGain Engineering - Plant Series HiGain HLU-D41
6.2 Provisioning the HLU-D41 Alarms. The HLU-D41 alarms are provisioned via the front-panel
Setup buttons or provisioning menus:

The ALRM HES and ALRM DS1 alarms can be suppressed by selecting NONE for the Errored
Seconds Alarm (ESAL) system option using the Mode and Choice Setup buttons (see Section
12) or the Maintenance Terminal menus (see Section 18.6).

The MAL alarm can be disabled by setting the margin alarm threshold to 0.

A Minor Alarm can be turned off by pressing the Choice Setup button on the front panel. This
also replaces the ALRM message displayed at the LCD front panel with the ACO (Alarm Cut
Off) message. The second part of the ALRM message, which defines the cause of the alarm,
remains. Both messages remain until the alarm condition clears or another alarm occurs.
6.3 When the HDSL loop loses sync word (LOSW), a minor alarm condition exists but because the
HLU-D41 enters a self test cycling mode, the front panel LED lights yellow instead of red and the
Self Test message is displayed instead of an ALRM message.
See Table 14 in Section 16 for alarm messages that display in the "Alarms" field of
the View Span Status screen.
B. INSTALLATION
7. Inspecting Your Shipment
7.1 When you receive the equipment, 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.
7.2 You shipment should consist of:
•One HLU-D41 List 2D
•This document

Revision 01 June 12, 1997 Section 150-441-124
HiGain HLU-D41 PairGain Engineering - Plant Series Page 9
8. HLU-D41 Card Edge Pin-Out Diagram
8.1 The HLU-D41 occupies one slot in an AT&T-type D4 channel bank or equivalent SLC-96 bank.
The card edge pin-out diagram for the HLU-D41 is shown in Figure 4.
Figure 4. HLU-D41 Card Edge Pin-outs

Section 150-441-124 June 12, 1997 Revision 01
Page 10 PairGain Engineering - Plant Series HiGain HLU-D41
8.2 More than one HLU-D41 may be installed in a channel bank. The physical time slots are identical to
the electrical DS0 time slots in D4 banks. Physical slots match the DS0 time slots as shown in Table
6. Depending on the slot position of the HLU-D41 and its bandwidth, certain channel bank slot
positions will not be available for use by other line units.
Table 6. Channel Bank Slot Positions
Physically Installed
Channel Slot Number of Provisioned Time Slots Next Available DS0 Time Slot
189
12 6 18
20 4 24
20 6 not recommended
The last example in Table 6 is not recommended because its bandwidth exceeds the
24-slot single digroup limit. This would require the HLU-D41 to wrap around and
add time slots 1 and 2 to 20 through 24. Most channel banks have a gaped clock
which prohibits this wrap feature.
8.3 Mode III Operation. The HLU-D41 can be used in SLC-96 banks configured for Mode III (special
service) operation. Since SLC-96 channel slots do not receive signaling frame information, SLC-96
HLU-D41 applications cannot be configured for RBS and are restricted to the CLR signaling option.
Table 7 shows the relationship between the physical and DS0 time slots for various settings of Band
and Slot for the two SLC-96 channel counting options. In addition, Mode III has two channel
counting sequences, such that the physical channel slots are not identical to the DS0 time slots. The
Mode III D1D and D4 channel counting sequences are shown in Table 8.
Table 7. Relationship Between Physical Slots and Timeslots in SLC-96 Banks
Timing
mode Band Slot* Physical slot DS0 time slots Blocked physical slots
DID 768K CONT 3 11, 12, 13, 14, 15...22 3, 9, 16, 22, 4, 10, 17, 23, 5,
11, 18, 24
DID 256K ALT 16 13, 15, 17, 19 16, 4, 17, 5
D4 768K CONT 5 9, 10, 11...20 5, 17, 6, 18, 7, 19, 8, 20, 9, 21,
10, 22
D4 256K ALT 18 18, 20, 22, 24 21, 22, 23, 24
* CONT=Conti
g
uous slot settin
g
ALT=Alternating slot setting
See Section 12 if confi
g
urin
g
timeslots usin
g
the front
p
anel Mode and Choice Setu
p
buttons, or Section
18.9 if configuring timeslots using the Maintenance Terminal menus.

Revision 01 June 12, 1997 Section 150-441-124
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Table 8. Channel Counting
D4 Channel Counting
Physical Slots 1 2 3 4567 8 9 101112
Time Slots 1 2 3 4567 8 9 101112
Physical Slots 13 14 15 16 17 18 19 20 21 22 23 24
Time Slots 13 14 15 16 17 18 19 20 21 22 23 24
SLC-96 Mode III D1D Channel Counting
Physical Slots 1 2 3 4567 8 9 101112
Time Slots 3 7 11 15 19 23 4 8 12 16 20 24
Physical Slots 13 14 15 16 17 18 19 20 21 22 23 24
Time Slots 1 5 9 13 17 21 2 6 10 14 18 22
SLC-96 Mode III D4 Channel Counting
Physical Slots 1 2 3 4567 8 9 101112
Time Slots 1 3 5 7 9 11 13 15 17 19 21 23
Physical Slots 13 14 15 16 17 18 19 20 21 22 23 24
Time Slots 2 4 6 8 10 12 14 16 18 20 22 24

Section 150-441-124 June 12, 1997 Revision 01
Page 12 PairGain Engineering - Plant Series HiGain HLU-D41
9. Installing the HLU-D41
9.1 The HLU-D41 is installed in a single-channel unit slot of a D4 or SLC-96 channel bank (Figure 5).
Figure 5. Installing an HLU-D41 in a Channel Bank
To install the HLU-D41 into a channel bank:
1Slide the HLU-D41 into the card guides for the desired slot, then push the unit in until it touches
the channel-bank backplane card-edge connector.
2Push the unit in until it is entirely within the card guide and the retaining latch locks into place
indicating that the unit is properly seated.

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10. Connecting to a Dumb Terminal
10.1 The 9-pin RS-232 connector on the front of the HLU-D41 allows you to connect your system to a
dumb terminal or PC running a terminal emulation program with a standard RS-232 cable. Once
connected to a dumb terminal, you can access the maintenance, provisioning, and performance
screens. Figure 6 shows the HLU-D41 DB-9 RS-232 I/O.
Figure 6. DB-9 RS-232 I/O

Section 150-441-124 June 12, 1997 Revision 01
Page 14 PairGain Engineering - Plant Series HiGain HLU-D41
10.2 The dumb terminal is configured as DCE. To connect the HLU-D41 to a dumb terminal, connect the
RS-232 COM port of the dumb terminal to the HLU-D41 front panel RS-232 connector using a serial
cable (Figure 7):
Figure 7. Connecting the HLU-D41 to a Dumb Terminal
11. Initialization
11.1 Power-up Sequence. When an HLU-D41 is first inserted into a channel bank, its bandwidth and
slot settings may exceed the intended setting for the new application. This could disrupt service in
an existing channel bank for the active channel timeslots if the HLU-D41 slot configuration conflicts
with another channel card’s DS0 data. A special power-up sequence is built into the HLU-D41 to
preclude this interference with another channel card’s DS0 data during the power-up initialization
mode.
11.2 Time Slot Assignments for Remote Units and Line Units. When installing the fractional T1
circuit, remember that the data at the remote unit (customer) side always begins at time slot 1 and
continues through the number of time slots provisioned. Data at the line unit begins at the time slot
assigned to the line unit’s physical slot position. For example, if the line unit is installed in the D4
channel bank in position 13 and the circuit is provisioned for four contiguous time slots of
bandwidth, then the data will be in time slots 13, 14, 15, and 16 at the line unit, but in time slots 1, 2,
3, and 4 at the remote unit.

Revision 01 June 12, 1997 Section 150-441-124
HiGain HLU-D41 PairGain Engineering - Plant Series Page 15
C. SETTING OPTIONS FROM THE FRONT PANEL
12. Using the Mode and Choice Setup Buttons
12.1 Option Settings. The Mode and Choice Setup buttons are used to set the system options from the
front panel. Table 9 lists the system options and defines each of the modes and settings. Options are
listed in the sequence in which they appear in the front panel LCD. Table 10 lists the four-digit LCD
messages. The front panel LCD has a maximum display of four digits, thus the first part of a
two-part message blinks for one second followed by the second part of the message.
The following three user options cannot be set using front panel Mode and Choice
Setup buttons, but must be set using the Maintenance Terminal menus: Circuit ID,
Margin Alarm Threshold, and Signaling.

Section 150-441-124 June 12, 1997 Revision 01
Page 16 PairGain Engineering - Plant Series HiGain HLU-D41
Table 9. System Options
Mode Choice Description
IDLE FF* Blocked channels are filled with Hex transmit code FF.
7F Blocked channels are filled with Hex transmit code 7F.
LPBK DIS* Disables the activation of NREM by NEI DDS code.
ENA Enables the activation of NREM by NEI DDS code.
PWRF DIS Prevents line powering over the HDSL pair.
ENA* Allows line powering over the HDSL pair.
ESAL 17 Causes a minor alarm dis
p
la
y
(flashin
g
red Status LED) when 17 Errored Seconds (ES) occur within a
24-hour period.
170 Causes a minor alarm display (flashing red Status LED) when 170 ES occur within a 24-hour period.
NONE* Prevents generation of a minor alarm due to excessive ES.
LBTO NONE Disables automatic time-out cancellation of all loopbacks.
20 Sets automatic time-out to 20 minutes.
60* Sets automatic time-out to 60 minutes.
120 Sets automatic time-out to 120 minutes.
DS1 AUTO The HRU inde
p
endentl
y
monitors its incomin
g
DS1 bit stream for the Binar
y
Ei
g
ht Zero Substitution
(B8ZS)
p
attern. If the HRU detects this
p
attern, it enters its B8ZS mode. It reverts back to its
Alternate Mark Inversion (AMI) mode if no B8ZS patterns are received for five seconds.
B8ZS Places the HRU into its B8ZS mode.
AMI* Places the HRU into its AMI mode.
SLOT ALT Customer data is trans
p
orted in Alternatin
g
DS0 time slots (1, 3, 5...23). Time slots 2, 4, 6, ... 24 are
not used.
CONT* Customer data is trans
p
orted in Conti
g
uous DS0 time slots (1, 2, 3...12). Time slots 13 throu
g
h 24 are
not used.
HAIS ENA* Enables the HRU to transmit the AIS si
g
nal toward the CPE when the HDSL loo
p
is not in s
y
nc
(LOSW) or when a margin alarm occurs.
DIS Prevents the HRU from transmittin
g
the AIS si
g
nal toward the CPE when a mar
g
in alarm occurs. AIS
is still transmitted when the HDSL loop is not in sync.
NAIS ENA* Enables the HRU to transmit the AIS signal toward the CPE when in NREM loopback.
DIS Enables the HRU to transmit an LOS condition (instead of the AIS si
g
nal) toward the CPE when in
NREM loopback.
BAND 01-12 Sets the bandwidth in 64K increments. For each
p
ress of the button, the dis
p
la
y
adds 64K, as well as
an additional channel to the system setting. One channel is 64K, 12 channels is 768K.
MARG Ran
g
e:
0 to 15 dB
Default: 4*
dB
The MARG (Mar
g
in Alarm Threshold) can onl
y
be set usin
g
the Maintenance Terminal menus. This
settin
g
determines the minimum allowable mar
g
in below which a minor alarm can occur. A 0 dB
setting disables this option.
SGNL RBS All DS0 channels in Robbed Bit Signaling (RBS) mode.
CLR* All DS0 channels in Clear Channel mode.
MIX Mix of RBS and Clear Channel modes.
CONF YES Confirms that all operating parameters (except Margin) are to be updated to the new selections.
NO* Prevents newl
y
selected o
p
eratin
g
p
arameters from bein
g
u
p
dated. These o
p
tions remain as the
y
were
before the setting options procedure was started.
* Default setting.