CopperOptics PairGain HiGain HDU-45 User manual

PAIRGAIN TECHNOLOGIES SECTION 150-451-132-02
Technical Practice Revision 02
Engineering - PLANT Series November 13, 1997
Copyright © 1997, PairGain Technologies, Inc. PairGain and HiGain are registered trademarks of PairGain Technologies, Inc.
Information contained in this document is company private to PairGain Technologies, Inc., and shall not be modified,
used, copied, reproduced or disclosed in whole or in part without the written consent of PairGain.
02 Page 1
P
AIR
G
AIN
®
T
ECHNOLOGIES
H
I
G
AIN
®
D
OUBLER
U
NIT
MODEL HDU-451 Issue 1
List 3B, PairGain #150-1143-32 CLEI Code: T1R5G54EAA
CONTENTS PAGE
A. PRODUCT OVERVIEW 2
1. DESCRIPTION AND FEATURES 2
2. APPLICATIONS 2
3. SPECIFICATIONS 3
4. CERTIFICATION 4
5. WARRANTY 4
6. TECHNICAL ASSISTANCE 4
B. FUNCTIONAL DESCRIPTION 4
7. OPERATIONAL CAPABILITIES 4
8. OUTSIDE ENCLOSURE DEPLOYMENT
RULES 6
9. FRONT PANEL 6
10. LOOPBACK DESIGN DESCRIPTION 7
11. MAINTENANCE PORT DISPLAYS 7
C. INSTALLATION AND TEST 9
12. INSTALLATION 9
13. TROUBLESHOOTING 10
CAUTION
This product incorporates static sensitive
components. Proper electrostatic discharge
procedures must be followed. Figure 1. HDU-451 List 3B Front Panel.
The PairGain
HDU-451 extends the range of HiGain repeaterless T1
transmission systems.

Section 150-451-132-02
Revision 02
Page 2
A. PRODUCT OVERVIEW
1. DESCRIPTION AND FEATURES
1.01 PairGains HiGain Model HDU-451 List 3B
low-power Doubler Unit (Figure 1) extends
the range of the HiGain repeaterless T1
transmission system. When installed between an
HLU List 6D HiGain Line Unit and an HRU-412
HiGain Remote Unit, the HDU-451 enables 1.544
Mbps transmission over an extended Carrier
Serving Area (CSA) range of approximately 24,000
feet of 24 AWG or 18,000 feet of 26 AWG wire.
Customers can use two doublers in series to triple
the normal CSA range (36,000 feet on 24 AWG).
1.02 The HDU-451 mounts in a single slot of any
industry-standard 400 mechanics shelf or in
equivalent enclosures manufactured by PairGain
Technologies. All HiGain modules comply with the
applicable requirements of TR-TSY-000063
(Network Equipment Building System (NEBS)
Generic Equipment requirements) and TR-TSY-
000499 (Transport System Generic Requirements -
TSGR).
1.03 Revision History of this practice.
a) Revision 01 - October 3, 1997
(initial release).
b) Revision 02 - November 11, 1997.
1.04 HDU-451 List 3B, HiGain Doubler Unit
features:
• Powered by all HLU doubler-compatible
line units - no local power required
• Front Panel HDSL Status Display
• Front panel jacks for test access
• Lightning and power cross protection on
the HDSL interfaces (both sides)
• Front Panel Doubler loopback LED
indicator
• Low power dissipation
1.05 In line with PairGain's continuing efforts to
provide equipment that fully complies with
new industry standards, the List 3B doubler has
been enhanced with a special ground fault-detecting
circuit described in Paragraph R7-1, Section 7.2.1 of
GR-1089-core, Issue 1, Revision 1, December,
1996.
When used with HiGain line units, ground faults
occurring at any point along any span on any wire
are immediately detected. This condition shuts the
HiGain circuit down. The line unit will periodically
try to apply power to the first span to determine
whether the fault condition is still present. As long
as the fault condition exists, the power cycling and
ground fault protection will continue.
Circuits containing both the new List B and older
doublers also support this new ground fault
detecting feature, provided the doubler nearest the
HLU is a List B unit. The presence of this new
circuit causes the HDSL span-powering voltage
levels to be shifted up to 100 volts more positive
than what they are in non-List B doubler circuits.
The actual shift depends on loop length, number of
doublers, HRU powering option, and the setting of
the HLU Bipolar/Unipolar Switch. The List B
doublers are backward-compatible with all versions
of HiGain line units.
The operation of the ground fault circuit
requires that the doubler enclosure be
connected to earth ground.
2. APPLICATIONS
2.01 The primary application of the HDU-451
HiGain Doubler is to extend the delivery of
T1 High-Capacity Digital Service (HCDS) to
customers over metallic cable pairs, up to 24,000 or
36,000 feet (24 AWG). A doubler application is
shown in Figure 2. Customers can use a maximum
of two HDU-451 units in tandem on a single service.
2.02 Table 1 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 and the HDU-451 as well as
between the HDU-451 and a second HDU-451 or the
HRU-412. Add 3 dB for each bridged tap and 1 dB
for each cable gauge change.

Section 150-451-132-02
Revision 02
Page 3
NID
SMJK
HRU-412
LIST 7*
HDSL
Doubler
2
HDU-451
HDSL
Doubler
1
HDU-451
HDSL
Central
Office
HLU-231
(List 6D/3D)
HLU-319
(List 2/3)
DSX
9,000' 26 AWG
12,000' 24 AWG 9,000' 26 AWG 12,000' 24 AWG -22.5 dB Max.
9,000' 26 AWG or 12,000' 24 AWG (without Doubler)
9,000' 26 AWG
12,000' 24 AWG
*Two Doubler application requires the locally powered HRU-412, List 7.
Any HRU-412 can be used for single Doubler applications.
Figure 2. HiGain Installation with Two Doublers.
The HDU-451 can extend the delivery of T1 High-Capacity Digital
Service (HCDS) to customers over metallic cable pairs, up to 24,000 or 36,000 feet (24 AWG).
TABLE 1. HDSL LOSS OVER CABLES
Cable Gauge Loss @ 196 kHz(dB/ft) Ohms per ft
26/0.4mm 3.880 83.3
24/0.51mm 2.841 51.9
22/0.61mm 2.177 32.4
19/0.91mm 1.535 16.1
2.03 The HiGain system operates with any
number of other T1, POTS, Digital Data
Service (DDS) or other HiGain Systems sharing the
same cable binder group.
3. SPECIFICATIONS
HDSL Line Code
784 kbps, 2B1Q full duplex
HDSL Output
+13 dBm ±0.5 dB @ 135 ohms
HDSL Line Impedance
135 ohms
HDSL Line Input DC resistive signature
330 kilohms
HDSL Line Output DC resistive signature
25 ohms
Maximum Provisioning Loss
35 dB @ 196 kHz, 135 ohms
Line Clock Rate
Internal Stratum 4 clock
HDSL Startup Time
15 seconds (typical), 30 seconds (maximum)
Power Consumption
6 watts (maximum)
Electrical Protection
Secondary surge and power cross protection on
all HDSL ports.
Operating Temperature and Humidity (non-
condensing)
-40° to + 65° Celsius, 5 to 95%
Operating Temperature in Outside Enclosures
Complies with Section 10.2.1.3 of TA-NWT-
001210. (See paragraph 8.01.)
Operating Elevation
200 feet below sea level to 13,000 feet above sea
level.
Mounting
Single-width, 400-type mechanics.

Section 150-451-132-02
Revision 02
Page 4
Dimensions
Height: 5.6  (14.22 cm)
Width: 1.4  (3.5 cm)
Depth: 5.6  (14.22 cm)
Weight
0.81 lb. (0.37 kg)
4. CERTIFICATION
4.01 FCC Compliance: The HDU-451 has been
tested and found to comply with the limits
for Class A digital devices pursuant to Part 15 of the
FCC rules. These limits are designed to provide
reasonable protection against harmful interference
when the equipment is operated in a commercial
environment. This equipment generates, uses and
can radiate radio frequency energy and, if not
installed and used in accordance with the instruction
manual, may cause harmful interference to radio
communications. Operation of this equipment in a
residential area is likely to cause harmful
interference in which case the user will be required
to correct the interference at his own expense.
4.02 Refer to the installation section of the
appropriate instruction manual for the unit
you are installing to get information on:
• Cabling
• Proper connections
• Grounding
• Line vs. local power
4.03 All wiring external to the product(s) should
follow the provisions of the current edition of
the National Electrical Code.
5. WARRANTY
5.01 PairGain Technologies warrants this product
to be free of defects and to be fully
functional for a period of 36 months from the date of
original shipment, given proper customer installation
and regular maintenance. PairGain will repair or
replace any unit without cost during this period if the
unit is found to be defective for any reason other
than abuse or improper use or installation.
5.02 This module should not be field repaired. If
it fails, replace it with another unit and return
the faulty unit to PairGain for repair. Any
modifications of the unit by anyone other than an
authorized PairGain representative will void the
warranty.
5.03 If a unit needs repair, call PairGain for a
Return Material Authorization (RMA)
number and return the defective unit, freight
prepaid, along with a brief description of the
problem, to:
PairGain Technologies, Inc.
14402 Franklin Avenue
Tustin, CA 92680
ATTN: Repair and Return Dept.
[phone]
5.04 PairGain will continue to repair faulty
modules beyond the warranty program at a
nominal charge. Contact your PairGain sales
representative for details and pricing.
6. TECHNICAL ASSISTANCE
6.01 PairGain Technical Assistance is available
24 hours a day, 7 days a week by
contracting PairGains Customer Service
Engineering group at one of the following numbers:
Telephone: [phone]
[phone]
Fax: [phone]
During normal business hours (8:00 AM to 5:00 PM,
Pacific Time, Monday - Friday, excluding holidays),
technical assistance calls are answered directly by a
Customer Service Engineer. At other times, a
request for technical assistance is handled by an on-
duty Customer Service Engineer through a callback
process. This process results in a callback within 30
minutes of initiating the request.
In addition, PairGain maintains a computer bulletin
board system for obtaining current information on
PairGain products, product troubleshooting tips and
aids, accessing helpful utilities, and for posting
requests or questions. This system is available 24
hours a day by calling [phone].
Transmission speeds up to 28.8 kbps are supported
with a character format of 8-N-1.
B. FUNCTIONAL DESCRIPTION
7. OPERATIONAL CAPABILITIES
7.01 HiGain utilizes PairGains Two-Bits, One-
Quaternary (2B1Q) HDSL transceiver
systems to establish two full-duplex 784 kbps data
channels (total of 1.568 Mbps) between the HLU
and a remotely mounted HRU-412 HiGain Remote
Unit. Each HDU-451 increases the total span of the

Section 150-451-132-02
Revision 02
Page 5
CSA by approximately 12,000 feet (24 AWG) or
9,000 feet (26 AWG).
7.02 A block diagram of the HDU-451 is shown in
Figure 3. The HDU-451 power supply uses
the 100 to 200V dc power feed voltage received on
the simplex pairs to produce +5V and -5V dc
required by the HDU-451 circuitry. The power feed
is passed to the HDSL Output to power one other
HiGain module, either a second HDU-451 or the
remote HRU-412. If you use two doublers, the
remote module must be a locally powered HRU-412
List 7 unit.
7.03 The maximum power dissipation of the
HDU-451 is 6 watts.
Figure 3. HDU-451 Block Diagram. Each HDU-451 increases the total span of the CSA by approximately 12,000 feet (24
AWG) or 9,000 feet (26 AWG).

Section 150-451-132-02
Revision 02
Page 6
8. OUTSIDE ENCLOSURE DEPLOYMENT
RULES
8.01 Customers must take care when deploying
the HDU-451 in sealed multislot outside
enclosures, such as the PairGain HRE-423. These
enclosures restrict the rate of heat transfer to the
outside ambient. This effect can cause excessive
heat build up if you do not follow the deployment
rules shown in Table 1. Note that the allowable
maximum outside ambient temperature is a function
of the number of occupied slots. All of the
applications in Table 1 exceed the temperature
requirement of Section 10.2.1.3 of TA-NWT-
001210. This section requires that HDSL equipment
deployed in outside enclosures shall operate in a
temperature, ambient outside the housing, of -40ºF
with no solar load to +115ºF with maximum solar
load and maximum power dissipation.
8.02 Customers may also enclose the doubler in
the PairGain single-slot HRE-450 outdoor
enclosure. Its thermal limits are also shown in
Table 1.
TABLE 1. HDU-451 DEPLOYMENT RULES FOR
HRE-423 AND HRE-450 ENCLOSURES
Ambient Temperature
(maximum) Solar Loading Number of
Doublers
HRE-423
120ºF (49ºC)
135ºF (57ºC) Full None 3 3
127ºF (52ºC)
142ºF (61ºC) Full None 2 2
140ºF (60ºC)
149ºF (65ºC)* Full None 1 1
HRE-450
149ºF (65ºC)* Full 1
Full Loading = Maximum sunlight exposure per
Section 10.2.1.3 of TA-NWT-001210.
None = Indoor, underground or fully shaded location.
*Maximum operating temperature.
9. FRONT PANEL
9.01 The front panel of the HDU-451 contains the
following connectors and indicators (see Figure 1):
• +/- V Jacks
These two test jacks enable you to monitor
the input voltage feed on the HDSL line.
Typical values range from 130V to 200V,
based on the distance from the HLU or first
HDU-451.
• LOOPBACK LED Indicator
Each HDU-451 supports two loopbacks as
described in Section 10: NDU (1 or 2) and
CDU (1 or 2). NDU1 (NDU2) loops back
towards the Network through the HLU.
CDU1 (CDU2) loops back toward the
customer through the HRU-412. The
LOOPBACK indicator has the following
states:
Green indicates loopback NDU1 or
NDU2 is active.
Yellow indicates loopback CDU1 or
CDU2 is active.
Flashing Yellow indicates the doubler
is in an armed state ready to accept a
16-bit intelligent loopback command
issued at the HLU or HRU-412 DS1
inputs.
• HDSL IN LED Indicators
Two LEDs indicate the status of the two
HDSL input line pairs: HDSL IN 1 and
HDSL IN 2 . These indicators have the
following states:
Flashing Green indicates
synchronization is being attempted with
the HLU.
Green indicates HDSL frame
synchronization between the HLU and
HDSL input.
Flashing Red indicates an HDSL error
Yellow indicates a Margin alarm at this
HDSL port.
• HDSL OUT LED Indicators
Two LEDs indicate the status of the two
HDSL output line pairs: HDSL OUT 1 and
HDSL IN 2 . These indicators have the
following states:

Section 150-451-132-02
Revision 02
Page 7
Flashing Green indicates
synchronization is being attempted with
the HRU-412 or a second HDU-451.
Green indicates HDSL frame
synchronization between the HDSL output
and the HRU-412 or a second HDU-451.
Flashing Red indicates an HDSL Error
Yellow indicates a Margin alarm at this
HDSL port.
• RS232 Connector
The HDU-451 List 3B supports a full set of
maintenance, test and status menus and
displays on an ASCII terminal attached to
the RS-232 front panel connector. (See
Figure 4 for the RS-232 connector
pinouts.) The array of displays are shown
in Figures 7 through 24 at the end of this
practice. The port is configured as DCE
with 8 data bits, 1 stop bit, and no parity.
Striking the Spacebar several times
invokes the autobaud feature, which
covers a 1200 to 9600 bps range.
The technique by which the various
display information is obtained is called
remote log in. The doubler is actually
logged onto the HLU unit and obtains all
the display data from the HLU. This
saves memory space because it
eliminates the need to keep redundant
information in three different locations.
The consequence of this feature is that
only one doubler can be on-line and
logged in to the HLU at any given time.
Thus, you must log in each doubler (press
the Enter key) at the initial Log-On screen
shown in Figure 7.
When you log in either doubler, no one
can log in on the other doubler until you
log off the on-line doubler by choosing the
REMOTE LOG OFF selection from the
Main Menu, shown in Figure 8. To
prevent an operator from inadvertently
failing to log off and thereby preventing
another from logging on, an on-line
logged-in doubler will automatically log
itself off after five minutes of inactivity (no
keyboard strikes).
10. LOOPBACK DESIGN DESCRIPTION
10.01 Figure 5 shows the complete family of
loopbacks that a HiGain system can
execute. Four of these loopbacks, NDU1, NDU2,
CDU1, and CDU2, occur in the doubler. These
loopbacks can be initiated from the HLUs
maintenance port, the HLUs front panel
pushbuttons, and from a family of Special Loopback
(SPLP) in-band loopback commands. Figure 5 lists
the Generic, SPLP, in-band loop-up command set
for the four doubler loopbacks: 110000 (2 in 6) for
NDU1, 111000 (3 in 6) for NDU2, 111100 (4 in 6) for
CDU1 and 111110 (5 in 6) for CDU2. Refer to the
appropriate HLU practices for more details regarding
the other doubler loopback commands.
11. MAINTENANCE PORT DISPLAYS
11.01 Main Menu. Figure 8 is the main menu of
the maintenance terminal. Its five
submenus provide many useful provisioning, test,
and monitoring tools.
11.02 Status. Figures 9 through 12 show the
HDU-451 status displays. Span 1s display
contains data on the two HDSL loops between the
HLU and the first doubler. Span 2 refers to the
loops between the first doubler and the HRU-412 for
one-doubler circuits or between the first and second
doublers for two-doubler circuits. Span 3 refers to
the loops between the second doubler and the HRU-
412 for two-doubler circuits. All status screen
contain the same DS1 interface information.
11.03 System Settings. Figure 13 shows the
System Settings menu. You can set these
system options only at the HLU. The HDU-451
menu is a monitor only display.
HDU-451
DCE
FEMALE MALE
2
5
3
2
5
3
RD(RECEIVEDATA)
TD(TRANSMITDATA)
GND
DB9
DB9
DTE
DTE
TERMINAL
TERMINAL
3
2
7
DB25
Figure 4. HDU-451 DB-9 Pin Outs. A standard RS-232
(DB-9) connector on the front panel provides access to
the menu interface feature via a dumb terminal.

Section 150-451-132-02
Revision 02
Page 8
11.04 Performance Data. Figures 14 through 17
show the system Performance Data
displays. Both the Errored and Unavailable
Seconds for both HDSL loops and each T1 input are
listed at 15-minute intervals over a 4-hour time
duration. Span 1s display contains data on the two
HDSL loops between the HLU and the first doubler
HDU1. Span 2 refers to the loops between the first
doubler HDU1 and the HRU-412 for one-doubler
circuits or between the first and second doublers
(HDU1 and HDU2) for two-doubler circuits. Span 3
refers to the loops between the second doubler
and the HRU-412 for two-doubler circuits. All status
screens contain the same DS1 interface errors. You
can display earlier or later data, in four-hour
increments, by entering P (previous) or N (next),
respectively. You can display performance data
from the different spans by entering S (span). You
can set all of the counters to zero by selecting the
(C)lear option from the HLU Status Screen only.
Note that since the HLU is considered the master
module, executing its Clear function clears all
performance data screens at both the HLU, the
HDUs, and the HRU-412.
Figure 5. HiGain Loopbacks.

Section 150-451-132-02
Revision 02
Page 9
11.05 7-Day History. Figures 18 through 21 show
the system 7-Day History Performance Data
displays. The Errored and Unavailable Seconds for
both HDSL loops and each of the two DS1 inputs
are listed for the Current and the seven previous
days. Span 1s display contains data on the two
HDSL loops between the HLU and the first doubler
HDU1. Span 2 refers to the loops between the first
doubler HDU1 and the HRU-412 for one-doubler
circuits or between the first and second doublers
(HDU1 and HDU2) for two-doubler circuits. Span 3
refers to the loops between the second doubler and
the HRU-412 for two-doubler circuits. All status
screens contain the same DS1 interface errors. You
can set all of the counters to zero by selecting the
(C)lear option from the HLU Status Screen
11.06 Alarm History. Figures 22 through 24 show
the system Alarm History screens. The
alarms are defined in the HLU-231 List 6D Technical
Practice, 150-231-164. The LOS and PWR system
alarms are common to all spans. Only the LOSW,
ES, and MARGIN are span-specific alarms. The
PWR-OPEN and SHORT alarms indicate conditions
on the HLU span as measured by the HLU. Neither
PWR alarm is available on the other spans. The
First and Last columns contain the time and date
stamp of the first and last occurrence of each alarm.
The Current column shows the status of each alarm.
The Count column lists the number of times each
alarm occurred. You can clear all the data with the
(C)lear command. The maximum non-overflowing
count is 999. Span 1s screen concerns alarms that
occurred on the two HDSL loops between the HLU
and the first doubler HDU1. Span 2 refers to the
loops between the first doubler HDU1 and the
HRU-412 for one-doubler circuits or between the
first and second doublers (HDU1 and HDU2) for
two-doubler circuits. Span 3 refers to the loops
between the second doubler and the HRU-412 for
two-doubler circuits.
C. INSTALLATION AND TEST
12. INSTALLATION
12.01 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.
12.02 The HDU-451 mounts in the following
PairGain Remote Enclosures:
• HRE-423 (three-slot, double-width,
outdoor, above or below ground)
• HRE-450 (single-slot, outdoor, above
ground)
• HRE-420 (single-slot, indoor)
• HRE-422 (two slot, single width, indoor)
12.03 The HDU-451 also mounts in any industry-
standard 400-type multi-mount shelves.
Pin-outs used by the HiGain Doubler Unit are shown
in Figure 6.
12.04 The number of HDU-451 List 3B units that
you can deploy in a doubler enclosure is
determined by the ambient temperature and the
solar loading. See Section 8 for further information.
12.05 Before installing the HDU-451, mount and
cable the HiGain Remote Enclosure as
described in the appropriate enclosure document.
Figure 6. HDU-451 List 3B Pin-Outs. Active pins are
highlighted in black.

Section 150-451-132-02
Revision 02
Page 10
12.06 Insert the HDU-451 into a slot in the Remote
Enclosure.
12.07 If the HLU List xD in the CO is operational,
the HDSL IN LED indicators will light within
30 seconds.
12.08 If the HRU-412 at the customer site is
installed and operational, the HDSL OUT
LED indicators will light and remain lit within one
minute.
12.09 The front panel HDSL IN (loop) 1 and HDSL
IN (loop) 2 LED indicators identify the cable
pairs coming into the doubler from the upstream
location. The pairs are identified by the polarity of
the simplex voltage that is applied to them by the
upstream unit, the HLU or the HDU-451. Loop 1 has
the - simplex voltage. Loop 2 has the + simplex
voltage. Thus, if the input pairs are swapped, as is
often done during troubleshooting sessions to isolate
the problem to either the upstream or down stream
direction, the HDU-451 will continue to identify loop
1 as the - pair and loop 2 as the + pair. Therefore, if
the problem remains with the same pair, as
identified by the HDU, before and after the pairs are
swapped, the problem is upstream or towards the
pair. For example, assume the HDSL IN 1 LED is
flashing red, indicating errors on loop 1. If the pairs
are swapped and the HDSL IN 1 LED continues to
flash the indicated problem is towards the upstream
cable pair or attached equipment. If the HDSL 2 IN
LED begins flashing, the problem lies toward the
HDU-451 unit itself.
13. TROUBLESHOOTING
13.01 Table 3 provides step-by-step
troubleshooting procedures for common
problems. Refer to the functional block diagram in
Figure 3 and the connector pin-outs in Figure 6.
TABLE 3. HDU-451 TROUBLESHOOTING PROCEDURES
Step Action
Case 1LEDs do not light
1 Verify the HLU is installed and operational in the central office. Verify proper cabling between the Doubler
Enclosure and the central office.
2Measure 100 to 210V dc at the HDU-451 front panel jacks (
+/-V ). This voltage peaks every 15 seconds as
the HLU powers up. If less than 130V dc is present, suspect cabling or the HLU. Only the line units listed in
Paragraph 1.05 can be used to power doublers. Other HLU versions may sometimes seem to work but will
not provide reliable operation and should not be used.
Case 2HDSL OUT LEDs do not light
1 Verify the HRU-412 at the customer site is installed and operational in the central office. The HRU-412
HDSL input has a signature resistance of 180 kOhms between the Tip and Ring on each loop.
2 Verify that the central office HLU complies with Paragraph 1.05.
Case 3HDSL LEDs flash green continuously
1If the
OUT LEDs are flashing, verify the HRU-412 is operational and the cables between the HDU-451 and
HRU-412 are intact.
2If the
IN LEDs are flashing, verify the HLU is operational and the cables between the HLU and HDU-451 are
intact.
Case 4HDSL IN LEDs light when HDSL OUT LEDs flash
1 No HRU-412 at the remote end. Measure the input resistance of the HRUs HDSL path at the HDU-451.
The HRU-412 HDSL input has a signature resistance of 180 kOhms between the Tip and Ring on each loop.
2 Loop resistance or attenuation is out of specification (resistance should be less than or equal to 800 Ohms,
attenuation should be less that or equal to 35 dB.
Table continued on next page

Section 150-451-132-02
Revision 02
Page 11
TABLE 3. HDU-451 TROUBLESHOOTING PROCEDURES (CONTINUED)
Case 5HDU-451 loses power
1 The HLU at the central is not present. Measure the resistance of the HDSL input loop. Resistance
should be normal loop resistance plus the 25-Ohm signature of the HLU-231 List xD.
TABLE 4. HDU-451 STATUS MENU MESSAGES
Message Full Name Description
ALARMS
NONE No Alarms
LLOS Local Loss of Signal No signal from local T1 interface.
RLOS Remote Loss of Signal No signal from remote T1 interface.
MNR Minor Alarm A Minor Alarm condition is in effect.
LOSW Loss of Sync Word One of the HDSL loops has lost synchronization.
H1ES HDSL Loop 1 Errored Second Loop 1s CRC has exceeded the user-selected Errored
Seconds threshold.
H2ES HDSL Loop 2 Errored Second Loop 2s CRC has exceeded the user-selected Errored
Seconds threshold.
DS1 Digital Service 1 DS1 input BPVs have exceeded the user-selected Errored
Seconds threshold.
ACO Alarm Cut Off An Alarm Cut Off is in effect.
LAIS Local Alarm Indicating Signal Indicates an AIS (all 1s) pattern is being transmitted from the
local T1 output port.
RAIS Remote AIS Indicates an AIS (all 1s) pattern is being transmitted from the
local T1 output port.
HDSL-1(2) HDSL Loop 1(2) Defines HDSL loop 1(2) in any given span.
MAL 1(2) Margin Alarm 1 (2) The Margin on HDSL loop 1 (2) has dropped below the
threshold (1 to 15) set by the user.
LOOPBACKS
SMJK Smartjack Loopback Loopback at HRU-412 toward network initiated by 2 in 5 in-
band loopback code or out-of-band ESF data link code. See
Figure 5.
NREM Network Remote Loopback Loopback at HRU-412 (remote) toward network initiated from a
family of special loopbacks (SPLP), HRU-412 front panel
push-button, or maintenance terminal. See Figure 6.
Table continued on next page

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TABLE 4. HDU-451 STATUS MENU MESSAGES (CONTINUED)
NLOC Network Local Loopback Loopback at HLU (local) toward network initiated from a family of
special loopbacks (SPLP) or by depressing both the MODE and
SEL HLU-231 front panel pushbuttons or mantenance terminal.
See Figure 5.
NDU1 Network Doubler 1 Loopback Loopback at Doubler 1 towards network initiated from CO
(network) by a family of special loopbacks (SPLP) or from
maintenance terminal or by depressing both the MODE and SEL
HLU front panel pushbuttons. See Figure 5 and Section 10.
NDU2 Network Doubler 2 Loopback Loopback at Doubler 2 towards network initiated from CO
(network) by a family of special loopbacks (SPLP) or from
maintenance terminal or by depressing both the MODE & SEL
HLU front panel pushbuttons. See Figure 5 and Section 10.
CLOC Customer Local Loopback Loopback at HRU-412 (local) toward CI initiated from CPE
(customer) by a family of special loopbacks (SPLP) or from
maintenance terminal or by depressing both the MODE and SEL
HLU front panel pushbuttons. See Figure 5.
CREM Customer Remote Loopback Loopback at HLU (remote) toward customer initiated from CPE
(customer) by a family of special loopbacks (SPLP) or from
maintenance terminal or by depressing both the MODE & SEL
HLU front panel pushbuttons. See Figure 5.
CDU1 Customer Doubler 1
Loopback Loopback a Doubler 1 toward CI initiated from CPE (customer) by a family of special loopbacks (SPLP) or from maintenance
terminal or by depressing both the MODE and SEL HLU front
panel pushbuttons. See Figure 5.
CDU2 Customer Doubler 1
Loopback Loopback a Doubler 1 toward CI initiated from CPE (customer) by a family of special loopbacks (SPLP) or from maintenance
terminal or by depressing both the MODE & SEL HLU front panel
pushbuttons. See Figure 5.
ARM Armed HiGain has detected the intelligent repeater loopback (2 in 5)
arming code.
TLOS Transmit Loss Of Signal
loopback HRU-412 is in a logic loopback state caused by a loss of its T1 input from the NI, if enabled via the TLOS option switch in the
HRU.

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TABLE 5. GLOSSARY OF HIGAIN TERMS
Term Definition
MARGINS Indicates the excess signal-to-noise ratio, at either the HLU or HRU-412, relative to a
10
-7
Bit Error Rate. First value is current margin, second value is minimum margin
since (C)leared last, third value is maximum value since cleared, and NA means Not
Available. The normal range of a typical margin is from 22 to 6 dB.
PULSE ATTENUATION Indicates the attenuation of the 2B1Q pulse from the distant end. HiGain operates
with pulse attenuations in excess of 30 dB. This value is related to the cable pairs
196 kHz loss. The pulse attenuation is a more direct indication of the loop
attenuation to the 2B1Q signal than the 196 kHz loss. The normal range of pulse
attenuation is from 1 to 32 dB
PPM Indicates the relative offset of the crystal oscillator in the HRU-412 from the HLUs
crystal oscillator. Any value between -64 and +64 is adequate. Values outside this
range indicate out of tolerance components or excessive temperature drift of critical
components.
HDSL 24 Hour ES
(Errored Seconds) The number of one-second intervals that contained at least one CRC error. This value is a running total of the last 24 Hours.
HDSL 24 Hour UAS
(Unavailable Seconds) The number of seconds the HDSL loop was out of synchronization.
DS1 BPV Seconds (ES) The number of seconds in which at least one bipolar violation was detected on the
DS1 input.
DS1 UAS Count The number of seconds during which the DS1 input signal was absent (125 or more
consecutive 0s)
Frame type Type of DS1 framing used on the input stream (SF, ESF, Unframed or No Activity).
Code type Type of DS1 line coding used (AMI, B8ZS, AMI : ZBTSI or B8ZS : ZBTSI). The latter
two conditions indicate the code type that is being received when HiGain is set to its
ZBTS mode. In either the AMI or B8ZS DS1 code mode, it displays the selected
code. In the AUTO mode it displays the code being received.
HLU/ver x.x-yyyy
HRU/ver x.x-yyyy
HDU1/ver x.x-yyyy
HDU2/ver x.x-yyyy
x.x = the software version number of the HLU, HRU-412, or HDU-451.
yyyy = the list number of the HLU, HRU-412, or HDU-451.

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Figure 7. Doubler Log-In Screen
Figure 8. HDU-451 Main Menu.

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Figure 9. Status Display Span 1 (1 or 2 Doublers).
Figure 10. Status Display Span 2 (1 Doubler).

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Figure 11. Status Display Span 2 (2 Doublers).
Figure 12. Status Display Span 3 (2 Doublers).

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Figure 13. System Settings Menu
Figure 14. Performance Data Span 1 (1 or 2 Doublers)

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Figure 15. Performance Data Span 2 (1 Doubler)
Figure 16. Performance Data Span 2 (2 Doublers)

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Figure 17. Performance Data Span 3 (2 Doublers)
Figure 18. Performance Data History Span 1 (1 or 2 Doublers)

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Figure 19. Performance Data History Span 1 (1 Doubler)
Figure 20. Performance Data History Span 2 (2 Doublers)