CopperOptics PairGain HiGain ELU-319 List 5 User manual

PAIRGAIN TECHNOLOGIES Section 150-319-251
Technical Practice Revision 01
Engineering - PLANT Series July 6, 1995
Page 1
PAIRGAIN TECHNOLOGIES HIGAIN™LINE UNIT
MODEL ELU-319 Issue 1
List 5, PairGain #150-1236-05 (75 Ohm)
List 6, PairGain #150-1236-06 (120 Ohm)
CONTENTS PAGE
A. PRODUCT OVERVIEW 2
1. DESCRIPTION AND FEATURES 2
2. APPLICATIONS 2
3. SPECIFICATIONS 3
4. CERTIFICATION 3
5. WARRANTY 4
6. TECHNICAL ASSISTANCE 4
B. FUNCTIONAL DESCRIPTION 4
7. OPERATIONAL CAPABILITIES 4
8. SYSTEM PARAMETER SETTINGS 7
9. MAINTENANCE PORT OPERATION 8
10. LOOPBACK DESIGN DESCRIPTION 9
C. INSTALLATION AND TEST 10
11. INSTALLATION OPTIONS 10
12. TESTING PROCEDURES 11
CAUTION
This product incorporates static sensitive
components. Proper electrostatic discharge
procedures must be followed.
Figure 1. ELU-319 Front Panel. The PairGain ELU-319
is the local unit used in conjunction with the ERU-412
remote unit to provide a complete HiGain HDSL system.

Section 150-319-251
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A. PRODUCT OVERVIEW
1. DESCRIPTION AND FEATURES
1.01 PairGain's HiGain Line Units Model ELU-
319, Lists 5 and 6 (Figure 1), are the Public
Exchange side of a repeaterless G.703 transmission
system. When used with an ERU-412 HiGain
Remote Unit (ERU), the system provides 2.048
Mbps transmission on two unconditioned copper
pairs. The HiGain system uses HDSL (High-bit-rate
Digital Subscriber Line) transmission technology as
recommended by Bellcore TA-TSY-001210. HiGain
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 01—July 6, 1995
a) Initial release.
b) This initial release is supported by
software version 1.3.
1.03 The ELU-319 is compatible with the
PairGain 22-slot HMS-318 shelf and the
associated G.703 HiGain connector panel HCP-322.
1.04 ELU-319 Product Family:
• List 5: 75-ohm G.703 Impedance
• List 6: 120-ohm G.703 Impedance
1.05 ELU-319 Issue 1 features:
• -130V dc line power for
ERU-412 or EDU-451
• Four-digit front panel display for HDSL
signal/noise (S/N) margin configuration and
alarms
• RS-232 maintenance port
• Non-volatile configuration memory
• Front panel splitting and bridging access to
G.703 interface
• Lightning and power cross protection on
HDSL interfaces
• 1040 kbps full-duplex two-bits one-
quaternary (2B1Q) HDSL transmission on
each of two pairs
• Front panel status-indicating light-emitting
diode (LED) indicator
• On / Off front-panel display power cycling
• G.703 Loss of Signal (LOS) detector (125
consecutive zeros)
• Margin threshold alarm
• Single step default setting
• Circuit ID option
• Improved tolerance to cable noise
• Supports EDU-451 doubler
2. APPLICATIONS
2.01 The HiGain System provides a cost-
effective, easy to deploy method for
delivering G.703 High Capacity Digital Service
(HCDS) over metallic pairs. The fiber-like quality
service is deployed over two unconditioned, non-
loaded copper pairs. Conventional span repeaters
are not required. Cable pair conditioning, pair
separation and bridged tap removal, are also not
required.
2.02 The HiGain system operates with any
number of other G.703, Plain Old Telephone
System (POTS), digital or analog data service or
other HiGain Systems sharing the same cable
binder group. HiGain provides a means of quickly
deploying service in advance of fiber-optic
transmission systems. By using HiGain G.703, you
can connect service within a few days or even a few
hours. You can install fiber optic systems at a
leisurely pace and cut-over from HiGain when the
time allows. You can then easily remove the HiGain
and utilize it elsewhere.
2.03 Table 1 provides a guide for the loss of
various cable gauges at the HDSL line rate
of 260 kHz and 135 ohms. The table applies to the
HDSL cable pairs between the ELU and the EDU-
451 as well as between the EDU-451 and a second
EDU-451 or the ERU-412. Add 3 dB for each
bridged tap and 1 dB for each cable gauge change.
TABLE 1. HDSL CABLE LOSS
Cable Gauge Loss @ 260 kHz(db/km) Ohms per km
26/0.4mm 13.94 272
24/0.51mm 10.47 171
22/0.61mm 8.14 105
19/0.91mm 5.74 52

Section 150-319-251
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2.04 The ELU to ERU operating ranges, on
unimpaired cable pairs, are shown in Table
2 as a function of cable gauge and average margin.
TABLE 2. HIGAIN E1 RANGES (KM) ON
UNIMPAIRED CABLES VS AVERAGE
MARGIN(M) IN DB
Cable Gauge M = 11 M = 7 M = 3
0.4 mm / #26 AWG 2.7km 3.0km 3.3km
0.51 mm / #24
AWG 3.6km 4.0km 4.4km
0.61 mm / #22
AWG 4.7km 5.2km 5.7km
0.81 mm / #19
AWG 6.6km 7.3km 8.0km
2.05 The ELU-319, List 5 and 6 line units can
only support applications requiring an ERU
(remote unit) or one ERU and one EDU (double
unit). They can not support two doubler
applications. For one doubler applications the ERU
must be locally powered.
3. SPECIFICATIONS
HDSL Line Code
1040 kbps, 2B1Q
HDSL Output
+13.5 dBm ± 0.5 dB @ 135 ohms
HDSL Line Impedance
135 ohms
Maximum Provisioning Loss
35 dB @ 260 kHz, 135 ohms
Line Clock Rate
Internal Stratum 4 clock
HDSL Startup Time
30 seconds (typical), 60 seconds (maximum)
One-way G.703 Delay
Less than 220 microseconds
G.703 Line Impedance
List 5: 75 ohms
List 6: 120 ohms
G.703 Input Level
+1.5 to -7.5 dB
G.703 Line Rate
2.048 Mbps ± 200 bps
G.703 Line Format
HDB3
Power Consumption
14 watts (typical), 18 watts (maximum)
Heat Dissipation
6 watts (typical), 8 watts (maximum)
Fusing
Internal, 1.25 amps @ 125V; connected to
FUSEALARM output on pin 10
Span Voltage
-136V dc ± 4V dc
Margin Indicator
Displays span SNR margin for both spans relative
to 10-7 BER operation
Electrical Protection
Secondary surge protection on G.703 and HDSL
ports
Power cross protection on HDSL ports
Operating Temperature and Humidity
-40° to 65° Celsius, 5 to 95% (non-condensing)
Mounting
STS, 28-slot, high-density shelf
Dimensions
Height: 4.75 in. (12.07 cm)
Width: 0.7 in. (1.78 cm)
Depth: 10.5 in. (26.67 cm)
4. CERTIFICATION
4.01 FCC compliance: The ELU-319 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.

Section 150-319-251
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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 installation. 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 voids 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]
[phone]
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] or [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 2-Bits-1-
Quaternary (2B1Q) HDSL transceiver
systems to establish two full-duplex 1040 Kbps data
channels between the ELU-319 and an ERU-412
HiGain Remote Unit. This provides a total capacity
of 2.080 Mbps between the two units - 2.048 Mbps
for the G.703 interface and 32 Kbps of overhead.
7.02 A block diagram of the ELU-319 is shown in
Figure 2. The HiGain ELU-319 receives a
2.048-Mbps data stream from the G.703 digital
cross-connect interface.
7.03 The ELU-319 contains a demultiplexer that
generates two parallel 1040 kbps data
streams. Each data stream consists of HDSL
frames that are nominally 4704 bits (4.5
milliseconds) in length. Each frame contains a 14-
bit Frame Sync Word (FSW), a 6-bit Cyclic
Redundancy Check (CRC), a 21-bit operations
channel and 16 of the 32 G.703 timeslots. The
demultiplexer provides frame synchronization for
each of the two HDSL channels. The multiplexer
and HDSL transceivers work under control of the
ELU-319 microprocessor and compensate for data
inversions caused by tip-ring reversals and for
channel swaps caused by pair reversals. The
HiGain system allows for tip-ring (pair) reversals, but
does not tolerate split pairs.
7.04 The two formatted HDSL channels pass to
the HDSL transceivers, which convert them
to 2B1Q format. The 2B1Q line code operates in
full-duplex mode on unconditioned pairs. The
transceiver's digital echo cancelers and adaptive
equalizers receive the signal from the remote end in
the presence of impairments and noise on the
copper pairs. HDSL channel 1 contains G.703
timeslots 1 through 16. HDSL channel 2 contains
G.703 timeslots 17 through 32.
7.05 The transceiver processes the HDSL
channels it receives and passes them on to
the ELU-319 multiplexer. The multiplexer removes
data link messages from the HDSL channels and
passes them to the microprocessor. This enables
the ELU-319 and the ERU-412 Remote Unit to
exchange operations messages and status. By
synchronizing to the FSW of each channel, the
multiplexer can reconstruct the original 2.048 Mbps
G.703 stream from the payloads of the two HDSL
channels. The CRC fields on the HDSL streams

Section 150-319-251
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enable the ELU-319 to determine if errors are
present on the channel due to excessive
impairments caused by impulse or crosstalk noise.
7.06 The reconstructed HDSL data channel is
buffered in a first-in-first-out (FIFO) buffer
within the multiplexer. A frequency synthesizer in
conjunction with the buffer regulates the output bit
rate and reconstructs the G.703 clock at the exact
rate received from the remote end. The HiGain
system operates at G.703 rates of 2.048 Mbps with
up to ±50 ppm of offset.
7.07 A G.703 interface driver converts the G.703
channel to a High Density Bipolar 3 (HDB3)
format.
7.08 The transmit and receive G.703 ports have
splitting access and bridging “Bantam”-type
jacks. Connecting one cable between the two BDG
jacks and another between the two LINE jacks splits
the XMT and RCV and creates metallic loopbacks
towards both the customer equipment and the HDSL
line.
7.09 The ELU-319 contains two separate power
converters. The main power supply
converts -48V local battery to logic power for the
ELU-319 circuits. The line power supply converts
the -48V battery to a -130V feed that provides
simplex power feed on the HDSL loops. The line
power can be turned on or off by the microprocessor
and automatically shuts down in the presence of line
short-circuits or microprocessor failure.
7.10 The three most important power demands of
an ELU-319 on the shelf power supply are
its maximum power consumption, its maximum
power dissipation, and its maximum current drain.
These three parameters for the ELU-319, on a per
slot and per shelf basis, are as follows:
Maximum Power Dissipation
Per slot: 8.0W
Per shelf: 176W
Maximum Power Consumption
Per slot: 18W
Per shelf: 396W
Maximum Current Drain
Per slot: 0.423A
Per shelf: 9.3A
Figure 2. ELU-319 Block Diagram. PairGain’s HDSL technology provides full-duplex services at 2.048 Mbps over copper
wires between an ELU-319 and an ERU-412, which comprise one HiGain system.

Section 150-319-251
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7.11 Note that the worst case conditions under
which these parameters were measured
include a 2.51-km, 0.4-mm loop, a fully loaded 22-
slot shelf, and a -42.5V shelf battery voltage. The
front panel display is assumed to be in its normally
OFF state (paragraph 11.01).
7.12 The Maximum Power Dissipation measures
the power that is converted into heat build
up within the unit. It contributes to the total heat
generated in the space around the unit. It is used to
determine the maximum number of fully loaded
shelves per bay that does not exceed the maximum
allowable power dissipation density in watts/square
meter (W/m2).
7.13 The thermal loading limitations imposed
when using the ELU-319 in controlled
environmental vaults (CEVs) or other enclosures are
determined by applying the ELU-319 power
parameters to the manufacturer's requirements for
each specific housing.
7.14 The Maximum Power Consumption is the
total power the ELU-319 consumes or draws
from its -48V shelf power source. This parameter is
needed when the ELU-319 is located remote to its
serving exchange. It determines the battery
capacity required to maintain an 8-hour standby
battery reserve for emergency situations. It thus
limits the maximum number of plugs per remote
enclosure. Use the above data to perform this
analysis case by case.
7.15 The Maximum Current Drain is the
maximum current drawn from the shelf power
supply when it is at its minimum voltage (-42.5V).
This determines the shelf fusing requirements.
ELU-319 shelves have two separate 48V buses.
Each bus is fused at 10A for a total of 20A per shelf.
A fully loaded shelf with 22 ELU-319 units draws
9.3A in the worst case. This is well within the 20A
fuse limit.
7.16 An RS-232 connector (DB-9) on the front
panel provides access to HiGain
maintenance, provisioning and performance
monitoring interface. Basic functionality is available
via a 'dumb terminal'. Refer to Section 9 for ‘dumb’
operation procedures.
7.17 Pin H of the ELU-319 is the minor alarm
(MNRALM) output pin. This pin must never
operate above 0V or below -60V. The ELU-319
forces pin H to ground (maximum of 10 mA) for any
of the conditions listed below, with the
accompanying front panel message in bold letters.
More than one alarm condition can exist at any
given time, but the unit can display only one
message. For multiple alarms, only the highest
priority alarm appears. The alarms are listed in their
order of priority:
1) ALRM LOSW: Loss of synchronization in
either HDSL loop.
2) ALRM LLOS: Loss of ELU-319 G.703
input signal.
3) ALRM RLOS: Loss of ERU-412 G.703
input signal.
4) ALRM H1ES: HDSL Loop 1 exceeded
the 24-hour user-selected Errored-
Seconds threshold (refer to Section 7).
5) ALRM H2ES: HDSL Loop 2 exceeded
the 24-hour user-selected Errored-
Seconds threshold (refer to Section 7).
6) ALRM G.703: The total number of
bipolar violations (BPV) at the ELU and
ERU G.703 inputs exceeded the 24-hour
user-selected threshold refer to Section
7).
7) ALRM MAL1 (2): The margin on HDSL
Loop 1 (Loop 2) has dropped below the
Margin Alarm Threshold value set from
the Maintenance Port menu (refer to
Section 7).
7.18 Pin H (Figure 5) (MNRALM) of the ELU-319
remains grounded for the duration of the
alarm condition. The ELU-319 STATUS LED
flashes red for the duration of a minor alarm
condition. You can retire the MNALRM by pressing
the front panel SEL(ect) button, thus executing the
alarm cut-off (ACO) option. This turns the alarm off
and replaces the ALRM message with ACO. The
part of the message that defines the alarm remains
until the alarm condition clears or another alarm
occurs. Disabling the ALM also retires an ACO
condition.

Section 150-319-251
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7.19 Setting the ALM option to DIS(able) only
pre- vents the unit from activating the MNRALM
output alarm bus on pin H on a minor alarm event.
The STATUS LED still flashes red and the ALRM
message still appears.
7.20 The ELU-319 drives pin 10 (FUSEALARM)
to -48V whenever its on-board fuse opens.
Its normally floating output must never operate
above ground or below -80V. It can sink a current of
10 mA.
7.21 The ELU-319 Line Unit front panel tri-color
STATUS LED has the following states:
• GREEN - Normal operation
• FLASHING GREEN - HDSL acquisition
• FLASHING RED - MNRALRM (For
conditions see paragraph 6.17)
• RED - FUSEALRM
• YELLOW - Self-test in process or an ELU-
319 loopback in effect (CREM or Network
Local Loopback (NLOC))
8. SYSTEM PARAMETER SETTINGS
8.01 The operating mode of the ELU-319
depends on the settings of the following
system operating parameters:
• PWRF—Power Feed (HDSL line power)
• ESAL—Errored Seconds Alarm Threshold
• LBTO—Loopback Timeout
• ALM—Minor Alarm
• MARG—Margin Alarm Threshold
8.02 Table 3 lists the ELU-319 system
parameters and their optional settings. The
ELU-319 stores the settings of the system
parameters in non-volatile RAM to prevent their loss
in the event that shelf power is lost or the ELU-319
is unplugged.
8.03 No DIP-switches or jumpers are required to
set the ELU-319 configuration. You can set
the ESAL, LBTO, and MAL system parameter
options with the front panel pushbuttons (MODE and
SEL); you can set all parameters from the
maintenance terminal through the ELU-319 RS-232
interface as described in Section 8.
8.04 To initiate the Option Set mode from the
ELU-319 front panel, press and hold the
MODE button for one second. The front panel
message alternates between the system parameter
and its current setting. Press the SEL button to step
through all possible values (in sequence) of the
parameter being displayed. Press MODE when the
desired setting is displayed. This selects the next
configurable parameter. When you have selected
the last parameter, the display displays “CONF/NO”.
To return to original settings, press the MODE
button. To accept the new settings, press the SEL
button. This displays “CONF/YES”, installs the
changes, and returns to normal display mode. If you
do not press either button within 30 seconds, the
parameters return to their original values, and the
display returns to normal mode.
8.05 To set all parameters to their default values,
press and hold the SEL button for six or
more seconds. The message “DFLT/NO” appears
when you release the button. Press SEL again to
display “DFLT/YES” and accept the default values.
Press MODE to cancel and return to the original
values.
8.06 Press the MODE button for 3 or more
seconds to scroll through the ELU-319
software version number, List #, and all parameter
option settings.

Section 150-319-251
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TABLE 3. SYSTEM PARAMETER OPTION SETTINGS
Parameter Option Description
PWRF (Power Feed) DIS Disables powering to the ERU over the HDSL pairs.
ENA* Enables powering to the ERU over the HDSL pairs.
ESAL (Errored Seconds Alarm
Threshold) 17 Activates MNRALM (on pin H) after 17 Errored Seconds (17 HDSL CRC errors on either HDSL loop or a total of 17 BPVs and FERR) occur
within 24 hours.
170 Activates MNRALM (on pin H) when 170 Errored Seconds occur within
24 hours.
NONE* Prevents generation of a minor alarm due to excessive Errored
Seconds.
LBTO (Loopback Timeout) NONE Disables automatic time-out cancellation of all loopbacks.
20 Sets automatic cancellation of all loopbacks to 20 minutes after
initiation.
60* Sets automatic cancellation of all loopbacks to 60 minutes after
initiation.
120 Sets automatic cancellation of all loopbacks to 120 minutes after
initiation.
ALM (Minor Alarm) DIS* Retires an existing minor alarm on pin H by disabling its signal, and
prevents another minor alarm from occurring.
ENA Enables pin H to be grounded when a minor alarm condition occurs.
CONF (Confirm) YES Confirms that all 4 operating modes are to be updated to their current
choices.
NO* Prevents the most recently selected operating mode choices from being
updated. They remain as they were prior to entry of system option
settings procedure.
MARG (Margin Alarm
Threshold) 0 to 15
4*
Displays the Margin Alarm Threshold (in dB), set using the RS-232
Maintenance port. If the margin on either loop drops below this value, a
minor alarm is reported (MAL1 or MAL2). The factory Default is 4.
* Indicates the ELU-319 factory settings.
9. MAINTENANCE PORT OPERATION
9.01 To configure the ELU-319 from the
Maintenance port, connect an ASCII display
terminal to the RS-232 Maintenance port with a
cable configured as shown in Figure 3. The
maintenance port is configured as Data
Communications Equipment (DCE) with 8 data bits,
1 stop bit and no parity. Striking the SPACE bar
several times invokes the “autobaud” function over a
range of 1200 to 9600 bps.
9.02 The menus and informational screens
displayed by the terminal are shown in
Figures 7 through 23. From the Main Menu
(Figure 7), select C–SYSTEM SETTINGS. Entering
the letter in parenthesis of the parameter you want
to change scrolls the parameter through its options.
When you have made the new settings, enter C to
confirm.
9.03 Two user settings, Circuit ID, and Margin
Alarm Threshold, must be set from the
display terminal.
9.04 To set the Circuit ID, select H from the Main
Menu to display “Enter circuit ID # (24
characters max)”. Enter the circuit ID, press
ENTER, then press C to confirm the entry. If you
enter more than 24 characters, the terminal beeps
and accepts only the first 24 characters. The circuit
ID appears in all screens, and you cannot reset it to
a default as described in Paragraph 7.05.

Section 150-319-251
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ELU-319
DCE
FEMALE MALE
2
5
3
2
5
3
RD(RECEIVE DATA)
TD(TRANSMITDATA)
GND
DB9
DB9
DTE
DTE
TERMINAL
TERMINAL
3
2
7
DB25
Figure 3. ELU-319 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.
9.05 To set the Margin Alarm Threshold, select
G–SYSTEM SETTINGS and then select G–
MAR(G)IN ALM THRES. Enter the minimum
acceptable alarm threshold, from 0 to 15 dB. If the
margin for HDSL Loop 1 or 2 drops
below this
value
, the ELU-319 triggers a minor alarm, and the
front panel and status screen displays “MAL1” (Loop
1) or “MAL2” (Loop 2). Because a margin can never
be less than zero, setting a threshold of zero turns
this feature off.
9.06 To set the Clock, select B–SET CLOCK
from the Main Menu. Enter the new date and
time. Press U to update the ERU system time and
date.
9.07 The Maintenance Port also provides several
screens that display System Performance
and Alarm Status information. Figures 13 through
24 illustrate these screens. Table 6 defines the
terms used in the Alarm and System Setting
screens. The illustrations of the System Setting and
ELU Status screens show factory defaults with
optional values or settings in parentheses.
10. LOOPBACK DESIGN DESCRIPTION
10.01 All HiGain ELU/ERU system loop-up codes
must be initiated from either the front panel
pushbuttons or from the maintenance terminal. The
HiGain system does not respond to any
in-band
codes
.
10.02 Depressing both the MODE and SEL
pushbuttons on the front panel for at least
three seconds initiates a MANUAL loopback
session. This session allows the user to SEL one of
six HiGain loopbacks. The message “MAN LPBK”
appears on the front panel display (see Figure 4.)
followed by the message “NLO?”. If the SEL button
is now pressed, an NLOC loopback is executed and
the message changes from “NLO?” to “NLOC”. If
the MODE button is pressed instead of SEL button,
“NLO?” is replaced by “‘ND1?. This now allows an
NDU1 loopback to be executed (if it is a doubler
application) with the SEL button. If it is not a
doubler application, NRE? follows NLO?. If this
same routine is followed, all six loopbacks (NLOC,
NDU1, NREM, CLOC, CDU1, & CREM) are
presented and can be initiated in the sequence
listed. Note that NDU1 and CDU1 only can appear
in doubler applications. Once a loopback is
executed, it can be terminated and the next
loopback option presented by pressing the MODE
button. If neither button is pressed for 30 seconds
and no loopback is in effect, this manual loopback
session terminates and the normal margin displays
reappear. If any loopback is in effect, this 30-
second time-out is inhibited. The active loopback
and the manual loopback session continue until the
loopback times out in accordance with the user
LBTO setting. Only one loopback may exist at any
given time. Depressing both buttons, again for three
seconds terminates any active loopback, ends the
MANUAL loopback session, and returns the display
to normal.
10.03 Note that these same six loopbacks can be
initiated from the RS-232 maintenance port
by choosing LOOPBACK MODE, option D, from the
main menu. This displays the Loopback Menu,
shown in Figures 22 and 23, from which you can
initiate any of the six loopbacks.
10.04 The TLOS loopbacks (shown in Figure 4)is
controlled by a user switch option in the
ERU-412. When this option is enabled it forces the
ERU-412 into a logic loopback state when its G.703
input signal is lost. When this TLOS option is
disabled, it causes an AIS condition to occur at the
G.703 output of the ELU-319 when the G.703 input
to the ERU-412 is lost.

Section 150-319-251
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C. INSTALLATION AND TEST
11. INSTALLATION OPTIONS
11.01 Upon receipt of equipment, visually inspect
it for signs of damage. If the equipment has
been damaged in transit, immediately report the
extent of damage to the transportation company and
to PairGain Technologies.
11.02 The ELU-319 mounts in the PairGain HMS-
318 shelf. The auxilary PairGain connector
panel, HCP-322, connects to the HMS-318 shelf and
provides G.703, 75 ohm, BNC connector access to
each of the 22 slots. The ELU-319 slot pin-outs are
shown in Figure 5.
Figure 5. ELU-319 Pin-Outs. The active pins are
highlighted in black in this illustration.
Figure 4. ELU-319 Loopback Configurations. All loopbacks are initiated from the front panel pushbuttons or from the
maintenance terminal.

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12. TESTING PROCEDURES
12.01 Table 4 lists the four-character front panel
message displays of the ELU-319. This
display energizes when power is initially applied to
the ELU-319; it indicates system status and error
conditions. In order to conserve power, the display
de-energizes after five minutes if neither MODE or
SEL are pressed. The use of either button restarts
the 5-minute power-control timer.
12.02 If you encounter trouble with the G.703
interface, verify that the unit is making a
positive connection with the mounting assembly's
connector.
12.03 The transmit and receive G.703 ports have
splitting access and bridging miniature 210-
type jacks as shown in Figure 2. Connecting one
cable between the two BRG jacks and another cable
between the two SPAN jacks splits the XMT and
RCV jacks and creates metallic loopbacks towards
both the G.703 and the ELU-319.
TABLE 4. ELU-319 FOUR-CHARACTER FRONT PANEL MESSAGES
Message Full Name Description
CREM Customer Remote Loopback Signal from customer is looped back to customer at ELU-319.
NLOC Network Local Loopback G.703 signal is looped back to G.703 at ELU-319.
NDU Network Doubler Loopback Loopback at Doubler towards network.
CDU Customer Doubler Loopback Looback at Doubler towards CPE.
CLOC Customer Local Loopback Signal from Customer is looped back to customer at ERU-412.
NREM Network Remote Loopback G.703 signal is looped back to G.703 at the ERU-412.
TLOS Transmit Loss Of Signal ERU-412 is in a logic loopback state caused by a loss of its
G.703 input from the NI, if enabled via the ERU-412 TLOS
switch option set to ON.
LBPV Local Bipolar Violation A bipolar violation has been received at the G.703 input to the
ELU-319.
SIG 1 or 2 Signal 1 or Signal 2 The ELU & ERU transceivers are trying to establish contact with
each other on Loops 1 or 2 of Span 1.
S1L1 or 2 Signal 1 Loop 1 or Loop 2 The ELU and 1st doubler transceivers are trying to establish
contact with each other on Loops 1 or 2 of Span 1.
S2L1 or 2 Signal 2 Loop 1 or Loop 2 The 1st Doubler and ERU transceivers are trying to establish
contact with each other on Loops 1 or 2 of Span 2.
ACQ 1 or 2 Acquisition 1 or Acquisition 2 The ELU & ERU multiplexers are trying to establish
synchronization over each of Loops 1 or 2 of Span 1
A1L1 or 2 Acquisition 1 Loop 1 or
Loop 2 The 1st Doubler and ERU multiplexers are trying to establish synchronization with each other on Loops 1 or 2 of Span 1.
A2L1 or 2 Acquisition 2 Loop 1 or
Loop 2 The 1st Doubler and ERU multiplexers are trying to establish synchronization with each other on Loops 1 or 2 of Span 2.
H1ES HDSL CRC error on Loop 1.
H2ES HDSL CRC error on Loop 2.
ACO Alarm CutOff An MNRALM has occurred, and was retired to an ACO condition
by pressing the SEL button on the ELU-319 front panel.
Table continued on next page

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TABLE 4. ELU-319 FOUR-CHARACTER FRONT PANEL MESSAGES (CONTINUED)
Message Full Name Description
SELF TEST The ELU-319 is in a self test mode. This occurs every power
ON/OFF cycle. The self-test sequence includes the input
G.703 transceiver chip when the HDSL loops are not in sync.
This can cause the AIS pattern, normally transmitted from the
ELU during this time, to exhibit bipolar violations (BPVs).
ALRM Alarm Condition Exists A minor alarm MNRALM condition is in effect.
1=xx or 2=yy HDSL Loop Margins Indicates the worst-case signal-to-noise ratio measured for each
loop. A value of ‘06’ or greater is adequate for reliable system
operation.
PWR FEED
SHRT Power Feed Short Indicates a short-circuit between the two HDSL pairs, or the ERU-412 cannot communicate with the ELU-319 over good
cable.
PWR FEED
OPEN Power Feed Open Indicates an open circuit in the Tip and Ring of either HDSL pair.
BAD RT? No response from ERU The ELU-319 does not receive any response from the ERU-
412. Thus, the ERU’s integrity is questionable.
VER ELU Software Version # This is displayed during the System Settings review mode.
Press the Mode button for 3 seconds.
LIST 0xL ELU’s List # Displayed during System Settings review mode defined above.
LOSW Loss of Sync Word Indicates that one of the HDSL loops has lost synchronization.
Causes a minor alarm.
LLOS Local Loss of Signal Indicates that no signal is detected at the G.703 input to the
ELU-319. Causes a minor alarm.
RLOS Remote Loss of Signal Indicates that no signal is detected at the G.703 input to the
ERU-412. Causes a minor alarm.
G.703 G.703 BPV errors Indicates that the number of BPVs at the ELU-319 and ERU-
412 G.703 inputs that have exceeded the 24-hour ES threshold.
Causes a minor alarm.
MAL1(2) Margin Alarm Loop 1 or 2 The margin on HDSL loop 1 (2) has dropped below the
threshold (1 to 15 dB) set by the user.

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TABLE 5. ELU-319 STATUS MENU DEFINITIONS
Message Full Name Description
ALARMS
NONE No Alarms
LLOS Local Loss of Signal No signal from local G.703 interface.
RLOS Remote Loss of Signal No signal from remote G.703 interface.
LOSW 1 (2) Loss of (HDSL) Sync Word 1
or 2 HDSL LOOP 1 or 2 has lost frame sync.
H1ES HDSL Loop 1 Errored Second The number of Loop 1’s Errored Seconds has exceeded the
user-selected Errored Seconds threshold.
H2ES HDSL Loop 2 Errored Second The number of Loop 2’s Errored Seconds has exceeded the
user-selected Errored Seconds threshold.
G.703 G.703 G.703 input BPVs have exceeded the user selected ES
threshold.
MAL1 Margin Alarm (HDSL Loop 1) The margin on HDSL Loop 1 dropped below the Margin
Alarm Threshold (1 to 15). Setting the threshold to 0 (zero)
inhibits the alarm.
MAL2 Margin Alarm (HDSL Loop 2) The margin on HDSL Loop 2 dropped below the user Margin
Alarm Threshold (1 to 15). Setting the threshold to 0 (zero)
inhibits the alarm.
ACO Alarm Cut Off Al Alarm cut-off is in effect.
LAIS Local Alarm
Indicating Signal Indicates an AIS (all 1’s) pattern is being transmitted from the local G.703 output port.
RAIS Remote Alarm Indicating Signal Indicates an AIS (all 1’s) pattern is being transmitted from
the remote G.703 output port.
LOOPBACKS
NREM Network Remote Loopback Loopback at ERU-412 (remote) towards network initiated
from ERU-412 front panel pushbutton, or maintenance
terminal, or by pressing both the MODE & SEL ELU front
panel pushbuttons. See Figure 4.
NLOC Network Local Loopback Loopback at ELU-319 (local) towards network by pressing
both MODE and SEL pushbuttons on the ELU-319 front
panel. See Figure 4.
NDU Network Doubler Loopback Loopback at Doubler towards network initiated from
Loopback Mode menu screen or by pressing both the MODE
& SEL ELU front panel pushbuttons. See Figure 4.
CLOC Customer Local Loopback Loopback at ERU-412 (local) towards customer interface
(CI) initiated from the maintenance terminal or by pressing
both MODE and SEL pushbuttons on the ELU-319 front
panel. See Figure 4.
Table continued on next page

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TABLE 5. ELU-319 STATUS MENU DEFINITIONS (CONTINUED)
Message Full Name Description
CHREV Channels Reversed Channel (loop) 1 & 2 HDSL pairs are reversed at the EDU or
ERU line input ports.
CREM Customer Remote Loopback Loopback at ERU-412 (local) towards customer interface (CI)
initiated from the maintenance terminal or by pressing both
MODE and SEL pushbuttons on the ELU-319 front panel. See
Figure 4.
CDU Customer Doubler Loopback Looback at Doubler towards CI initiated from Loopback Mode
menu screen or by pressing both the MODE & SEL ELU front
panel pushbuttons. See Figure 4.
TABLE 6. GLOSSARY OF HIGAIN TERMS
Term Definition
MARGINS Indicates the excess signal to noise ratio, at either the ELU-319 or ERU-412, 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 (loops are not synchronized). The normal range of a typical margin is from
6 to 22 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
loss at 260 kHz. The pulse attenuation is a more direct indication of the loop
attenuation to the 2B1Q signal than the 260 kHz loss. The normal range of pulse
attenuation is from 1 to 32 dB.
PPM Indicates the relative offset (in parts per million) of the crystal oscillator in the ERU-
412 from the ELU-319’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 1-second intervals that contained at least 1 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.
G.703 BPV Seconds
(ES) The number of seconds during which at least 1 bipolar violation was detected at the G.703 input.
G.703 UAS Count The number of seconds during which the G.703 input signal was absent (125 or
more consecutive zeroes).
ELU/Ver x.x-yyyy
ERU/ver x.x-yyyy “x.x” = the software version number of the ELU-319 or ERU-412.
“yyyy” = the list number of the ELU-319 or ERU-412.

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Figure 6. Main Menu.
Figure 7. Span Status Display (no Doubler).

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Figure 8. Span 1 Status Display (in system with one Doubler).
Figure 9. Span 2 Status Display (in system with one Doubler).

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Figure 10. System Settings Menu.
Figure 11. Set Clock Menu.

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Figure 12. Performance Data Display (no Doubler).
Figure 13. Span 1 Performance Data Display (in system with no Doubler).

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Figure 14. Span 2 Performance Data Display (in system with no Doubler).
Figure 15. Performance Data History Display (no Doubler).

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Figure 16. Span 1 Performance Data History Display (in system with one Doubler).
Figure 17. Span 2 Performance Data History Display (in system with one Doubler).