CopperOptics PairGain HiGain-2 HRU-612 User manual

PAIRGAIN TECHNOLOGIES SECTION 150-612-100
Technical Practice Revision 02
Engineering - PLANT August 21, 1996
Page 1
PAIRGAIN™TECHNOLOGIES HIGAIN-2™REMOTE UNIT
MODEL HRU-612
List 1 PairGain #150-1218-01 CLEI Code: T1LIVC04AA
CONTENTS PAGE
A. PRODUCT OVERVIEW
1. GENERAL 2
2. APPLICATIONS 2
3. SPECIFICATIONS 3
4. CERTIFICATION 3
5. WARRANTY 4
6. TECHNICAL ASSISTANCE 4
B. FUNCTIONAL DESCRIPTION
7. FUNCTIONAL OPERATION 4
8. FRONT PANEL 6
9. OPTIONS 7
10. LOOPBACKS 9
C. INSTALLATION AND TEST
11. INSTALLATION 10
12. TESTING 11
CAUTION
This product incorporates static sensitive
components. Proper electrostatic discharge
procedures must be followed.
Figure 1. HRU-612 List 1 Front Panel. The PairGain
HRU-612 is the remote side of a single pair repeaterless
T1 transmission system.

Section 150-612-100
Revision 02
Page 2
A. PRODUCT OVERVIEW
1. DESCRIPTION AND FEATURES
1.01 PairGain’s HiGain-2 Remote Unit Model
HRU-612, Issue 1, List 1, Figure 1, is the
remote end of a single pair repeaterless T1
transmission system. When used in conjunction
with a HiGain-2 Line Unit HLU-611 the system
provides 1.544 Mb/s transmission on one
unconditioned copper pair over the cable ranges
shown in Table 1. The HiGain-2 system utilizes
2B1Q VHDSL (Very High-bit-rate Digital Subscriber
Line) transmission technology. HiGain-2 complies
with the ANSI T1E1.4, T1.403-1989 and T1E1.4/92-
002R2 technical standards & recommendations.
The HRU-612 List 1 mounts in a single slot of any
industry standard 400 mechanics shelf or in
equivalent enclosures manufactured by PairGain
Technologies. The system also complies with TR-
TSY-000063 (Network Equipment Building System
(NEBS) Generic Equipment requirements) and TR-
TSY-000499 (Transport System Generic
Requirements - TSGR) common requirements.
1.02 Revision History of this practice.
Revision 02 — August 21, 1996
a) Extended temperature ratings from 0°to
+50°C to -40°to +65°C.
b) Extended the PPM offset range from
±64PPM to ±100PPM.
1.03 Features of the HRU-612 Issue 1 List 1
HiGain-2 Remote Unit are as follows:
• ANSI T1.403 DS1 Customer Interface
• VHDSL Line Powered operation - no local
power required
• Front Panel DS1 and VHDSL Status
Display
• Generic & addressable repeater Loopback
activation codes.
• Metallic smart-jack loopback. Conforms to
TR-TSY-000312.
• RS-232 front panel terminal access for
craft
• Provisioning switches for CPE current,
RCV LBO and XMT LOS initiated
loopback or AIS.
• Front panel jacks for test access
• CPE current monitor test points
• Front panel VHDSL margin threshold
indicator.
• Lightning and power cross protection on
VHDSL and DS1 interfaces
• 1568 kb/s full-duplex 2B1Q VHDSL
Transmission on 1 pair
• DS0 blocking.
2. APPLICATIONS
2.01 The primary application of the HiGain-2
System is to provide a quick and cost-
effective way of delivering T1 High Capacity Digital
Service (HCDS) to customers over a metallic cable
pair. The HiGain-2 system can be deployed on 1
unconditioned, non-loaded pair of wires without
repeaters, and without the need for either bridged
tap removal or binder group separation.
2.02 The general guidelines, on which the range
deployment rules in Table 1 are based,
require that the VHDSL HiGain-2 loop (which
operates at twice the line rate of standard HiGain
HDSL products) have less than 35 dB of loss at the
2B1Q line rate of 392 kHz, @ 135 ohm source and
load impedances.
2.03 The HiGain-2 system operates with any
number of other T1, POTS, Digital Data
Service (DDS) or other HiGain-2 Systems sharing the
same cable binder group. HiGain-2 systems can be
used with customers requiring DS1 service on a
temporary or permanent basis. HiGain-2 also provides
a means of quickly deploying service in advance of
fiber-optic transmission systems. Using HiGain-2 T1
service can be connected within a few days or even a
few hours. Fiber optic systems can be installed at a
leisurely pace and cut-over from HiGain-2 when the
time allows. The HiGain-2 system can then be easily
removed and utilized elsewhere.
TABLE 1. HIGAIN-2 VHDSL LOOP LIMITS
Cable Gauge Loss @ 392
kHz dB/kft Ohms per kft Maximum Loop For 35 dB Loss Ohms @ Maximum Loop Length
26/0.4 mm 4.97 83.3 7.0 kft / 2.13 km 583
24/051mm 3.87 51.9 9 kft / 2.74 km 467
22/0.61mm 3.01 32.4 12 kft / 3.66 km 389
19/0.91mm 2.17 16.1 16 kft / 4.87 km 258

Section 150-612-100
Revision 02
Page 3
3. SPECIFICATIONS
VHDSL Line Code
1568 kb/s 2B1Q full duplex
VHDSL Output
+13 dBm +/- 0.5 dB @ 135 ohms
VHDSL Line Impedance
135 ohms
VHDSL Line DC resistive signature
180 Kohms
Maximum Provisioning Loss
35 dB @ 392 kHz, 135 ohms
Line Clock Rate
Internal Stratum 4 clock
VHDSL Startup Time
15 seconds typ., 60 seconds max.
One-way DS1 Delay
<220 microseconds
DS1 Line Impedance
100 ohms
DS1 Pulse Output
0 dB (LBO = 0), -15 dB (LB0 =15).
DS1 Input Level
> -22.5 dB
DS1 Line Rate
1.544 Mb/s +/- 200 bits/sec
DS1 Output Wander (MTIE & TVAR)
Compliant with Section 7.2.1 of the T1X1.3/90-
026R7 SONET committee report.
DS1 Line Format
AMI, B8ZS or ZBTSI
DS1 Frame Format
ESF, SF or unframed
Power Consumption
6 watts typ.:8 watts max.
Electrical Protection
Secondary surge and power cross protection on all
DS1 & VHDSL ports.
Operating Temperature & Humidity (non-
condensing)
-40º to +65º Celsius & 5-95%
Mounting
Single width 400 type mechanics slot.
Dimensions
5.6 “H x 1.4 “W x 5.6 “D.
Weight
1 Pound.
4. CERTIFICATION
4.01 FCC Compliance: The HRU-612 List 1 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 UL Recognized: The HRU-612 List 1 is a UL
Recognized component. Use normal
caution when installing or modifying telephone lines.
Dangerous voltages may be present. It is also
considered imprudent to install telephone wiring
during a lightning storm. Always disconnect all
telephone lines and power connections from wall
outlets before servicing or disassembling this
equipment.
4.03 CSA Certification: The HRU-612 List 1 has
been tested and found to comply with CSA
Standard C22.2-950 telecommunication features.
4.04 Refer to the installation section of the
appropriate instruction manual for the unit
you are installing for:
• Cabling information
• Proper connections
• Grounding information
• Line vs local power
All wiring external to the product(s) should follow the
provisions of the current edition of the National
Electrical Code.

Section 150-612-100
Revision 02
Page 4
5. WARRANTY
5.01 PairGain Technologies warrants this product
to be free of defects and to be fully functional
for a period of 60 months from the date of original
shipment, given proper 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.
14352 Franklin Avenue
Tustin, CA 92680
ATTN: Repair and Return Dept.
[phone]
[phone]
5.04 PairGain will continue to repair or replace
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. FUNCTIONAL OPERATION
7.01 HiGain-2 utilizes PairGain’s 2B1Q VHDSL
transceiver technology to establish a full-
duplex 1568 kb/s data channels between the HLU
and a remotely mounted HRU-612 HiGain-2 Remote
Unit.
7.02 The HRU-612 power supply converts the
metallic 170 Vdc power feed that is received
on the VHDSL pair to voltages and currents required
by the HRU-612 circuitry. The power supply
generates +5, -5 and 30 Vdc outputs. The 30V
output is converted to a 60 ma current feed used to
simplex power the NID (Network Interface Device).
Caution should be used when the HRU is used to
power CSUs. Some CSUs require more output
voltage than the 30 volts provided by the HRU. The
HRU can not power both an NID and a CSU at the
same time.
7.03 The HRU-612 typically dissipates 6 watts of
power and may consume up to 8 watts
when feeding 60 mA. of simplex current to the CI.
7.04 The worst case -48V power consumption by
a HiGain-2 system from the CO is 18 watts
per DS1 service.
7.05 A 9-pin (RS-232) DB-9 connector,
configured as DCE (see Figure 3), is
provided on the front panel of the HRU-612. This
provides access to the monitoring features of
HiGain-2’s maintenance, provisioning and
performance monitoring interface. A very basic
interface is available via a ‘dumb terminal’. Figures 7
through 13 show the menu selections that are
available from the terminal. Table 3 defines the
various terms used in the screen displays. The port
is configured as DCE with 8 data bits, 1 stop bit and
no parity. Striking the SPACE bar several times
invokes autobaud from 1200 to 9600 baud. Note
that if the RS-232 port in an HRE-421 is used to
access the HRU-612, a null modem must be used
since the HRE-421 is configured as DTE .

Section 150-612-100
Revision 02
Page 5
7.06 The HRU-612 provides embedded status
monitoring functions that are accessed via
the RS-232 port. A main menu, shown in Figure 7, is
presented when a terminal is connected as
described in the previous paragraph. Figures 7-13
illustrate the displays provided from the terminal port.
Information displayed shows the status of the HLU at
the distant end of the VHDSL spans as well as the
HRU-612. The HLU shares its status with the HRU-
612 via the embedded operations channel so there is
no need to physically connect to the distant end for
its status.
Figure 2. HLU-612 List 1 Block Diagram.

Section 150-612-100
Revision 02
Page 6
8. FRONT PANEL
8.01 DS1. The top 60% of the front panel
addresses the following DS1 interface
features.
• 60 MA MON
These two test points allow the 60 mA. CPE current
option, if selected, to be measured. The current
flowing is related to the voltage measured across the
“ + “ and “ - “ test points by the following relationship:
CPE CURRENT =1 MA / 1 MV.
Typical readings range from 55 to 65 mv which
equate to a 55 to 65 mA. current range.
• RCV & XMT ACCESS JACKS
These provide both splitting and monitor access
jacks to the CPE DS1 interface. See Figure 2 for
circuit details. Note that these jacks are transformer
isolated from the CPE DS1 metallic interface.
• ALM
REM LOS
RED LED that indicates a Loss Of Signal at the T1
input to the REMote (HLU) unit. This condition
causes the HRU to transmit the AIS pattern to
towards the CPE.
LOC LOS
RED LED that indicates a Loss Of Signal at the T1
input to the LOCal (HRU) unit. This condition causes
HiGain-2 to either transmit the AIS pattern towards
the DSX-1 or to execute a logic loopback in the HRU
as a function of the TLOS user option setting. See
Paragraph 9.01 for details.
• LB
NET
GREEN LED indicating the HRU is in a loopback
state in which the signal from the NETwork is being
looped back to the NETwork.
CI
YELLOW LED indicating the HRU is in a loopback
state in which the signal from the customer interface
(CI) is being looped back to the CI.
BUTTON
Depressing this front panel button for 5 seconds
forces the HRU into its NREM metallic loopback
state. The unit can be unlooped by either
depressing the button again for 5 seconds or via the
standard loopdown coded messages.
• CODE
B8ZS
GREEN LED indicating that the user DS1 code
option is set to B8ZS. If however the user DS1 code
option is set to AUTO, this LED indicates that the
code of the DS1 signal being received at the HRU’s
DS1 input is B8ZS.
AMI
YELLOW LED indicating that the user DS1 code
option is set to AMI. If however the user DS1 code
option is set to AUTO, this LED indicates that the
code of the DS1 signal being received at the HRU’s
DS1 input is AMI.
BPV
RED LED that flashes every time a Bipolar Violation,
other than those associated with a B8ZS code, is
received at the HRU’s DS1 input.
• FRM
ESF
GREEN LED indicating that framing pattern of the
signal being received at the HRU’s DS1 input is
ESF.
HLU-611
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 3. DB-9 Pin-outs.

Section 150-612-100
Revision 02
Page 7
SF
YELLOW LED indicating that framing pattern of the
signal being received at the HRU’s DS1 input is SF.
ERR
RED LED indicating a DS1 frame error has occurred.
Note the FRM LED remains off if the HRU input
pattern is unframed or if the HiGain-2 FRMG option
is set to its unframed (UNFR) mode.
8.02 VHDSL The lower 40% of the front panel
addresses the following VHDSL
interface features.
OK
GREEN LED that flashes while the VHDSL Loop is
synchronizing with the HLU. A solid green state
indicates that Loop is properly synchronized with the
HLU.
MAR
YELLOW LED indicating that the HRU’s S/N MARgin
on the VHDSL Loop has dropped below the user
defined margin threshold value. This option is set at
the HLU in the System Settings menu of the
maintenance interface system at the RS-232
maintenance port.
ES
RED LED that flashes ever second in which at least
one VHDSL CRC error is detected.
9. OPTIONS
9.01 The HiGain-2 List 1 system has several
special loopback (SPLB) options that are set
at the HLU. Refer to practice # 150-611-100 for
more details. The HRU also has three user options
set by switches located at the back of the unit as
shown in Figure 4. Each switch has two settings as
follows (refer to the block diagram in Figure 2 for
details):
• I-CPE
0
*: Sets the CPE current to 0 mA..
60:
Sets the CPE current to 60 mA to power an
external NID.
• TLOS-LB
DIS*
: A loss of the T1 XMT signal from the CPE
causes the HLU to transmit the AIS signal towards
the DSX-1 and does not cause the HRU to enter its
logic loopback state.
EN:
A loss of the T1 XMT signal from the CPE
forces the HRU to enter its logic loopback state
(TLOS in Figure 5). While in this loopback state, the
HRU transmits the AIS signal towards the CPE and
returns the Network signal back to the Network. The
HLU displays the message TLOS in its 4 character
front panel read-out. This condition remains until a
valid T1 signal is received from the CPE or until a
loopdown command is issued. Note that once the
TLOS initiated loopback has occurred, it can not
reoccur until the CPE T1 signal has been reapplied
and then removed. This “latching” feature prevents
the HRU from oscillating into and out of TLOS
loopback when a loopdown command is issued in
the absence of a T1 signal from the CPE.
Figure 4. HRU-612 Manual Switches

Section 150-612-100
Revision 02
Page 8
RLBO
0
*: Configures the T1 RCV LBO to 0 dB. This sets
the T1 output signal level from the HRU towards the
NI to 0 dB. This setting is recommended when the
HRU does not function as the NID but is connected
to en external NID. It allows the external NID to set
the appropriate NI level.
15
: Configures the T1 RCV LBO to -15 dB. This sets
the T1 output signal level from the HRU towards the
NI level to -15 dB. This setting is recommended
when the HRU functions as the NID.
Note that the “ * “ denotes the factory setting.
Figure 5. HRU-612 Loopbacks.

Section 150-612-100
Revision 02
Page 9
10. LOOPBACKS
10.01 Figure 5 shows all 4 HRU loopbacks. Of
these, a TLOS and CLOC are logic
loopbacks. They occur in the digital multiplexer
section of the HRU as shown in Figure 2.
10.02 Both the SMART-JACK and NREM
loopbacks shown in Figure 5 execute the
standard NID metallic loopback. The only difference
is their initiating sequence. NREM is initiated by the
HRV front panel pushbutton, the maintenance
terminal, the HLU front panel pushbuttons or the 3 in
7 in band commands. The SMART-JACK loopback
is only initiated by the standard 3 in 5 in band loop-up
command. It has two modes of operation as
determined by the two states (ENA or DIS) of the
SAIS user option. The ENA option causes the HRU
to transmit the AIS signal towards the NI. The DIS
option turns off this AIS/NI signal.
10.03 ENA: Upon detection of a valid SMART-
JACK loopback command, a metallic
loopback relay (see Figure 2 for its location) is
energized and the T1 interface chip transmits the
AIS pattern to the NI and also back to the HRU’s T1
receiver circuit. In addition, the customer’s T1 XMT
input is disconnected and terminated into 100 ohms.
The AIS pattern is examined by the HRU for its
overall integrity. This pre-looped tests lasts for about
100 milliseconds and terminates in one of the
following two conditions:
A, PRE-LOOP FAILED: If the transmit & receive all
1’s patterns do not match, a problem in the HRU is
indicated and HiGain-2 declares an HRU PRE-
LOOPBACK FAIL condition. This terminates the
loopback test and returns the HRU to its unlooped
normal state. Note that other circuit impairments
could also prevent the loopback from occurring.
B, PRE-LOOP PASSED:- If the transmit and receive
patterns do match, a HRU PRE LOOPBACK PASS
condition is declared. All active circuits are working.
The metallic loopback relay remains closed and, in
addition, a logic loopback within the HRU is enabled.
This logic loopback is required in order to present
the all 1’s pattern to the NI and at the same time to
loop the signal, being received from the network,
back towards the network. HiGain-2 is now in its
AIS/ENA “smart-jack” loopback state. It remains in
this state until a loopdown command is detected or
the default time out period (if enabled) expires.
10.04 When the HRU is in its AIS/ENA smart-jack
metallic loop back state, its T1 input LOS,
Code & Frame monitoring circuits are connected to
the unframed AIS pattern which is being looped back
to these circuits through the loopback relay. The
CPE input signal is no longer being monitored since
its input circuit has been opened and terminated into
100 ohms. This forces the FRM LED off, the LOC
LOS LED off and the CODE LED to indicate AMI if
the HLU CODE option is set to either AUTO or AMI.
It will indicate B8ZS if the CODE option is set to
B8ZS.
10.05 As can be seen, this AIS/ENA metallic
loopback scenario includes and therefore
tests all HiGain-2 active circuits and fully conforms
with TR-TSY-000312. In this sense it out performs
the loopback function found in most standard NID
devices since these devices do not include either the
AIS generator or the CI T1 LOS detector in their
loopback path.
10.06 DIS: This metallic loopback state is initiated
in the same manner as it is when the ENA
option is chosen. However, once initiated, the AIS
signal is not sent to the NI. Instead the network
signal is sent both towards the NI and through the
relay back towards the network. As before, the
customer’s T1 transmit input port is opened and
terminated into 100 ohms. No logic loopback is
required since the relay is performing the network
signal loopback function. This simple metallic
loopback state remains until a loopdown command is
issued or the default timer (if enabled) expires.
10.07 When the HRU is in its AIS/DIS smart-jack
metallic loop back state, its T1 input LOS,
Code & Frame monitoring circuits are connected to
the network’s signal which is being looped back to
these circuits through the loopback relay. The CPE
input signal is no longer being monitored since its
input circuit has been opened and terminated into
100 ohms. The FRM & LOC LOS LEDs indicate the
status of this signal from the network. The CODE
LED also indicates the code (AMI or B8ZS) of this
signal if the CODE option is set to AUTO. It will
indicate AMI or B8ZS if the CODE option is set to
either AMI or B8ZS respectively.
10.08 The user should be aware that this AIS/DIS
smart-jack mode does not check all of the
HRU’s circuits nor does it send an AIS alerting signal
to the NI. Thus it does not comply with TR-312
requirement to transmit the AIS pattern to the CI
during the maintenance loopback state.

Section 150-612-100
Revision 02
Page 10
10.09 All of the HRU loopbacks towards the
network (NREM & SMJK) are metallic/logic
(AIS/ENA) or metallic only (AIS/DIS) except for
the TLOS initiated loopback, which is logic only.
The SMJK identifying label indicates that the
loopback was initiated by the 3 in 5 in band
command. NREM is used to indicate that the
metallic loopback was initiated by other than the
3 in 5 command (3 in 7, 16 bit addressable
repeater commands or front panel push-button).
C. INSTALLATION AND TEST
11. INSTALLATION
11.01 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.
11.02 The HRU-612, List 1 is designed to mount in
PairGain’s HRE-421 (double width, single
mount), HRE-422 (double width, double mount),
HRE-424 (double width, 4 unit wall mount), HRE-420
(single width, single mount) or HRE-425 (10 unit wall
or rack mount) Remote indoor Enclosures. For
outdoor applications, the HRE-423 (3 unit) and HRE-
450 (single width, single mount) enclosures are
available. The HRU is also compatible with industry
standard 400 type multi-mount shelves. The HRU’s
pin-outs are shown in Figure 6. Figure 6. HRU-612 Pin-outs.

Section 150-612-100
Revision 02
Page 11
TABLE 2. HRU-612 Test Procedures.
Step Action
1 Depress the loopback LB button on the HRU front panel for at least 5 seconds.
2 Verify that the GREEN HRU front panel loopback LB NET LED turns on, indicating that the HRU is in its
digital (NREM) loopback state. Also verify, if possible, that the HLU displays the message ”NREM” also
indicating that the HRU is in loopback (see Figure 5).
3 Have the C.O. tester transmit a T1 test signal into the HLU and measure that the returned (looped) signal
is error free.
4 If the above test fails, remove the HRU from its loopback state by again depressing the HRU loopback
button for 5 seconds. Verify that the loopback NET LED is off.
5 Have the C.O. tester send the HLU (4 in 7) in-band loop-up (NLOC) for 5 seconds. Verify that the HLU
displays the message “ NLOC” indicating that the HLU unit is in its network loopback state.
6 Repeat step 3. If the test passes, the problem is in the cable pair or the HRU. If it fails, the problem is in
the C.O.
7 To verify that the proper ports are use for the VHDSL & DS1 pairs, use an ohm-meter to verify that the
VHDSL HRU-612 port has a 180 k T to R resistive signature in contrast to the DS1 ports which have a 15
ohm T to R resistive signature.
8 If the CPE 60 mA. switch option is set. Verify that the external NID is under power and that the voltage
across the HRU-612’s front panel “60 mA MON” test points measures between 55 and 65 mv. This
indicates that the CPE current is between 55 & 65 mA. Note that the external NID’s LOOP POWER
option must be set to its “THRU” position when powered by the HRU.
NOTE: When T1 loopback tests are made on the HiGain-2 system with external metallic loopback connections
at either end, the DS1 code that exists at the metallic loopback interface may be different from the DS1 code
being received at the opposite end when the DS1 user option is set to AUTO. For example, if the HRU has a
metallic loopback and the HLU’s receive pattern’s code is changed from AMI to B8ZS and then the all 0 pattern is
sent into the HLU, the HRU remains in its AMI mode and thus loops all 0’s. This causes the HRU to indicate a
LOS condition which then causes the HLU to output the AIS pattern.
12. TESTING
12.01 Table 2 provides a step by step test
procedure for the HRU-612 unit. This
procedure allows verification of the integrity of the
VHDSL channel to the HLU Line Hit as well as the
DS1 channels to the customer and the HLU DSX-1
interface. Table 3 lists the HLU status messages
which may also be helpful when coordinating turn-up
with CO personnel.
12.02 The HLU’s 4 character front panel has many
useful diagnostic messages. They are listed
in Table 3.
12.03 If trouble is encountered at the T1 interface,
verify that the unit is making a positive
connection with the mounting assembly’s connector.

Section 150-612-100
Revision 02
Page 12
TABLE 3. HLU 4 CHARACTER FRONT PANEL MESSAGES.
Message Full Name Description
CREM Customer Remote Loopback Signal from customer is looped back to customer at HLU-
611
NLOC Network Local Loopback DSX signal is looped back to DSX at HLU
CLOC Customer Local Loopback Signal from Customer is looped back to customer at HRU-
612
NREM Network Remote Loopback DSX signal is looped back to DSX at HRU
SMJK Remote Smartjack Loopback Signal from DSX is looped back at HRU by the HRU
smartjack module.
TLOS Transmits loss of signal HRU is in a logic loopback state caused by a loss of its T1
input from the NI, if enabled by the SAFS option.
FERR Framing Bit Error Occurred Framing bit error occurred at HLU T1 input
LBPV Local Bipolar Violation A bipolar violation has been received at the T1 input to the
HLU-611.
SIG1 Signal The HLU & HRU transceivers are trying to establish
contact with each other.
ACQ1 Acquisition The HLU & HRU multiplexers are trying to establish
synchronization over each loop.
HES HDSL CRC Error At least 1 CRC error on the VHDSL Loop in the last second.
ARM HiGain-2 System ARMED Armed to respond to Intelligent Repeater Loop Codes
ACO Alarm CutOff A MNRALM has occurred, and been retired to an ACO
condition, by depressing the SEL button on the HLU front
panel.
SELF TEST Self test The HLU is in a self test mode. This occurs every power
ON/OFF cycle.
ALRM Alarm Condition Exists A minor alarm condition is in effect.
M =xx VHDSL Loop Margin Indicates the power of the received VHDSL signal relative to
noise. Any value of ‘06’ or greater is adequate for reliable
system operation.
PWR FEED
SHRT Power Feed Short Indicates a short between the VHDSL pair.
PWR FEED
OPEN Power Feed Open Indicates an open circuit in the T&R of the VHDSL pair.
BAD RT? No response from HRU The HDSL Power Feed circuits are good but the HLU does
not receive any response from the HRU. Thus the HRU’s
integrity is questionable.
Table continued on next page

Section 150-612-100
Revision 02
Page 13
TABLE 3. HLU 4 CHARACTER FRONT PANEL MESSAGES (CONTINUED)
Message Full Name Description
VER HLU Software Version # This is displayed during the System Settings review mode.
Depress the Mode button for 3 seconds.
LIST 0xL HLU’s List # Displayed during System Settings review mode defined
above.
FRM Frame:SF,ESF,UNFR,NONE Defines the type of frame pattern being received from the
DSX-1. Displayed during System Settings mode defined
above.
CODE Line Code: AMI, B8ZS This is the line code that the HLU is set to receive and
transmit at its DSX-1 interface. Displayed during System
Settings mode defined above.
LOSW Loss of Sync Word Indicates that the VHDSL loop has lost sync. Causes a
minor alarm.
LLOS Local Loss of Signal Indicates that no signal is detected at the T1 input to the
HLU. Causes a minor alarm.
RLOS Remote Loss of Signal Indicates that no signal is detected at the T1 input to the
HRU. Causes a minor alarm.
DS1 DS1 BPV errors Indicates that the number of BPVs at the HLU and HRU
DS1 inputs that have exceeded the 24 hour ES threshold.
Causes a minor alarm
DS0 DS0 Blocked Channels Indicates status of DS0 blocked channels. NONE indicates
no channels are blocked. BLK indicates some channels are
blocked.

Section 150-612-100
Revision 02
Page 14
TABLE 4. HRU-612 STATUS MENU DEFINITIONS
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
LOSW Loss of Sync Word The VHDSL loops has lost sync.
HES VHDSL Loop Errored
Second The VHDSL CRC errors have exceeded the user selectable ES threshold
DS1 Digital Service 1 BPV’s have exceeded the user selectable ES threshold.
R(L)AIS Alarm Indicating Signal Indicates an AIS (all 1’s) pattern is being transmitted from the
remote(R) or Local (L) T1 output port.
LOOPBACKS
SMJK Smartjack Loopback Loopback at HRU towards 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 (remote) towards network initiated by intelligent line repeater code, HRU or HLU front panel push-button or
maintenance terminal . See Figure 5.
NLOC Network Local Loopback Loopback at HLU (local) towards network initiated by intelligent
office repeater code or HLU front panel push buttons or
maintenance terminal. See Figure 5.
CLOC Customer Local Loopback Loopback at HRU (local) towards CI initiated by intelligent line
repeater code or HLU front panel push buttons or maintenance
terminal. See Figure 5.
CREM Customer Remote
Loopback Loopback at HLU (remote) towards customer initiated by intelligent office repeater code or HLU front panel push buttons or
maintenance terminal. See Figure 5.
ARM Armed HiGain-2 has detected the intelligent repeater loopback (2 in 5)
arming code.
TLOS Transmit Loss of Signal HRU is in its TLOS initiated loopback state.

Section 150-612-100
Revision 02
Page 15
TABLE 5. GLOSSARY OF HIGAIN TERMS
Term Definition
MARGINS Indicates the excess signal to noise ratio, at either the HLU or HRU, relative to a 10-
7 Bit Error Rate. 1st value is current margin, 2nd value is minimum margin since
(C)leared last, 3rd value is maximum value since cleared and NA means Not
Available.
PULSE
ATTENUATION Indicates the attenuation of the 2B1Q pulse from the distant end. HiGain-2 operates with nominal pulse attenuations up to 28 dB. This value is related to the cable pair’s
392 kHz loss. The pulse attenuation is a more direct indication of the loop
attenuation to the 2B1Q signal than the 392 kHz loss.
PPM Indicates the relative offset of the crystal oscillator in the HRU-612 from the HLU-
611’s crystal oscillator. Values usually range from -100 to +100.
VHDSL 24 Hour ES
(Errored Seconds) The number of 1 second intervals that contained at least 1 CRC error. This value is a running total of the last 24 Hours.
VHDSL 24 Hour UAS
(Unavailable Seconds) The number of seconds the VHDSL loop was out of sync.
DS1 BPV Seconds
(ES) The number of seconds in which at least 1 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 0’s)
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-2 is
set to its ZBTS mode. In either the AMI or B8ZS DS1 code mode, it displays the
selected code as opposed to the code type that is actually being received.
Ver Vw.xL “w.x” = the software version number of the HLU
Vw.xR “w.x” = the software version number of the HRU.
yzL “yz” = List number of the HLU
yzR “yz” = List number of the HRU.

Section 150-612-100
Revision 02
Page 16
FIGURE 7. HRU-612 MAIN MENU.
Figure 8. HRU Status Display.

Section 150-612-100
Revision 02
Page 17
FIGURE 9. Set Clock Menu.
Figure 10. System Settings Menu.

Section 150-612-100
Revision 02
Page 18
Figure 11. Performance Data.
Figure 12. Performance Data History.

Section 150-612-100
Revision 02
Page 19
Figure 13. HLU Alarm History.