Pairgain Higain -2 hlu-611 User manual

PARGAIN TECHNOLOGIES SECTION 150-611-103

Technical Practice Revision 01

Engineering - PLANT Series July 14, 1995

Page 1

PAIRGAIN TECHNOLOGIES HIGAIN-2™LINE UNIT

MODEL HLU-611 Issue 1

List 3 PairGain #150-1217-03 CLEI Code: T1L1JJK3AA

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. FUNCTIONAL OPERATION 4

8. OPTIONS 7 8

9. LOOPBACKS 8 9

C. INSTALLATION AND TEST 12

10. INSTALLATION 12

11. TESTING 13

CAUTION

This product incorporates static sensitive

components. Proper electrostatic discharge

procedures must be followed.

Figure 1. HLU-611 Front Panel. The PairGain HLU-611

is the Central Office side of a single pair repeaterless T1

transmission system.

Section 150-611-103

Revision 01

Page 2

A. PRODUCT OVERVIEW

1. DESCRIPTION AND FEATURES

1.01 PairGain’s HiGain-2 Line Unit Model HLU-

611 Issue 1, List 3 Figure 1, is the Central

Office side of a single pair repeaterless T1

transmission system. When used in conjunction

with an HRU-612 HiGain-2 Remote Unit, the system

provides 1.544 Mb/s transmission on 1

unconditioned copper pair over the cable ranges

shown in Table 1. The HiGain-2 system uses

VHDSL (Very High-bit-rate Digital Subscriber Line)

transmission technology. HiGain-2 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 14, 1995

a) Initial release.

1.03 HLU-611, List 3 features:

• Selectable DSX-1 Pre-equalizer

• -170 Vdc Line Power for HRU-612

• Front Panel VHDSL S/N Margin Display

• Selectable Loopback activation codes

• RS-232 maintenance port

• Non-volatile front-panel operator setup

• Front Panel DS1 splitting & brdg access

• Lightning and power cross protection on

VHDSL interfaces

• 1568 kb/s full-duplex 2B1Q VHDSL

Transmission on pair

• Front panel status indicating LED.

• On / Off front-panel display power cycling.

• DS1 LOS detector (125 consecutive

zeros).

• Margin threshold alarm.

• Smart-jack AIS option.

• Easy return to factory default user

settings.

• Circuit ID option

2. APPLICATIONS

2.01 HiGain-2 provides a cost-effective, easy to

deploy method for delivering T1 high

Capacity Digital Service (HCDS) over 1 metallic pair.

The fiber-like quality service is deployed over 1

unconditioned, non-loaded copper pair.

Conventional in-line T1 repeaters are not required.

Cable pair conditioning, pair separation and bridged

tap removal, are not required.

2.02 The general guidelines on which the range

deployment rules in Table 1 are based

require that each HiGain-2 loop have less than 35

dB of loss at the 2B1Q line rate of 392 kHz, with 135

ohm driving and terminating impedances, adherence

to this rule will result in an operating margin of at

least 6 dB. 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. With

HiGain-2, service can be provided within hours.

Fiber optic systems can be installed at a leisurely

pace and cut-over from HiGain-2 when convenient

to do so. 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 150-611-103

Revision 01

Page 3

3. SPECIFICATIONS

VHDSL Line Code

1568 kb/s 2B1Q.

VHDSL Output

+13.5 dBm +/- 0.5 dB @ 135 ohms .

VHDSL Line Impedance

135 ohms.

Maximum Provisioning Loss

35 dB @ 392 kHz, 135 ohms.

Line Clock Rate

Internal Stratum 4 clock.

VHDSL Startup Time

30 seconds typ., 60 seconds max.

One-way DS1 Delay

<220 microseconds.

DSX-1 Line Impedance

100 ohms.

DSX-1 Pulse Output

12V pk-pk for EXTERNAL equalizer or pre-

equalized for 0-655 feet of ABAM.

DSX-1 Input Level

+1.5 to -7.5 dBDSX.

DS1 Line Rate

1.544 Mb/s +/- 200 bits/sec.

DS1 Line Format

AMI, B8ZS or ZBTSI.

DS1 Frame Format

ESF, SF or unframed.

Power Consumption

14 watts typ.; 18 watts max.

Heat Dissipation

6 watts typ.; 8 watts max.

Fusing

Internal;connected to “FUSEALARM” output on

pin 32.

Span Voltage

-170 Vdc max.

Margin Indicator

Displays span SNR margin for both spans relative

to 10-7 BER operation.

Electrical Protection

Secondary surge protection on DS1 & VHDSL

ports. Power cross protection on VHDSL port.

Operating Temperature & Humidity

0 to 50º Celsius, 5 to 95% (non-condensing)

Mounting

AT&T 220 type or equivalent.

Dimensions

5.9”Hx1.4”Wx10”D.

MICROPROCESSOR

-FUSE

ALAR M

POWER

SUPPLY

34TIP1

RING 1

VHDSL

STATUS

RS-232

TIP

RING

RCV

TIP1

RING 1

SPAN

XMT

BRG

MUX

DEMUX

PRE-

EQUALIZER

SELECT

MODE SEL

170V

POWER

SUPPLY

(ISOLATED)

ALRM

GND

BAT

-48V

Figure 2. HLU-611 Block Diagram.

Section 150-611-103

Revision 01

Page 4

4. CERTIFICATION

4.01 FCC compliance: The HLU-611 has been

tested and found to comply with the limits

for a 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.

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.

(714) 832-9922

(800) 638-0031

6. TECHNICAL ASSISTANCE

6.01 PairGain Technical Assistance is available

24-hours-a-day, 7-days-a-week by

contacting PairGain’s Customer Service Engineering

group at one of the following numbers:

Telephone: (800) 638-0031

(714) 832-9922

Fax: (714) 832-9924

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 (714) 730-3299.

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 systems to establish one full-

duplex 1568 kb/s data channels between the HLU-

611 and a remotely mounted HRU-612 HiGain-2

Remote Unit.

7.02 A block diagram of the HLU-611 is shown in

Figure 2. The HiGain-2 HLU-611 receives a

1.544 Mb/s DS1 data stream from the DSX-1 digital

cross connect interface. The HLU contains a DS1

frame synchronizer controlled by an 8-bit micro

controller that determines the type of framing on the

DS1 stream and synchronizes to it. The HLU-611

recognizes SF(including D4) or ESF framing. When

the data is unframed, the HLU-611 arbitrarily defines

a frame bit.

Section 150-611-103

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7.03 The HLU-611 contains a demultiplexer that

generates a 1568 kb/s data stream. The

data stream contains VHDSL frames that are

nominally 9408 bits (6 milliseconds) in length. The

VHDSL frames contains a 14 bit Frame Sync Word

(FSW), 6 bit Cyclic Redundancy Check (CRC), 21

bit operations channel and DS1 payload.

7.04 The formatted VHDSL channel is passed to

the VHDSL transceiver which converts it to

a 2B1Q format on the VHDSL line. The 2B1Q line

code is designed to operate in a full-duplex mode on

one unconditioned pair. The transceiver’s echo

canceler and adaptive equalizer receive the signal

from the remote end in the presence of impairments

and noise on the copper pair.

7.05 The received VHDSL channel is processed

by the transceiver and then passed on to the

HLU-611 multiplexer module. The multiplexer

provides frame synchronization for the VHDSL

channel. The multiplexer and VHDSL transceiver

work under control of the HLU-611 micro controller

and compensate for data inversions caused by tip-

ring reversals. By synchronizing to the FSW of the

VHDSL channel, the multiplexer can reconstruct the

original 1.544 Mb/s DS1 stream from the VHDSL

channel. The CRC fields on the VHDSL streams

allow the HLU-611 to determine if errors are present

on the channel due to excessive impairments on the

VHDSL pairs or due to excessive impulse or

crosstalk noise.

7.06 The multiplexer removes data link

messages from the VHDSL channel and

passes them to the micro controller. This

mechanism allows operations messages and status

to be exchanged between the HLU-611 and the

HRU-612 remote unit.

7.07 The reconstructed VHDSL data channel is

buffered in a first-in-first-out buffer (FIFO)

within the multiplexer. A frequency synthesizer in

conjunction with the FIFO regulates the output bit

rate and reconstructs the DS1 clock at the exact

rate received from the remote end. The HiGain-2

system operates at DS1 rates of 1.544 Mbs with up

to ±200 bits/second of offset.

7.08 A DSX-1 interface driver converts the DS1

channel to an AMI or B8ZS format. The

DSX-1 equalizer is programmable to 5 different

lengths as determined by the distance between the

HLU and the DSX-1 interface. This provides CB-

119 compliant pulses at the DSX-1 interface over a

range of 0-655 feet of ABAM cable.

7.09 The HLU-611 contains 2 separate power

converters. The main power supply

converts -48V local battery to logic power for the

HLU-611 circuits. The line power supply converts

the -48V battery to a -170 Vdc feed that provides

loop power feed on the cable pair to the HRU Unit.

The line power supply can be turned on or off by the

micro controller and is automatically shut down in

the presence of line short circuits or micro controller

failure.

7.10 The three most important power demands of

an HLU-611 on the shelf power supply are

its maximum power consumption, its maximum

power dissipation and its maximum current drain.

These three parameters for the HLU-611, on a per

slot and per shelf basis, are as follows:

Maximum Power Dissipation:

• Per Slot = 7.0 Watts

• Per Shelf =91 Watts

Maximum Power consumption:

• Per Slot = 16 Watts

• Per Shelf =208 watts

Maximum Current Drain:

• Per Slot = 0.376 Amps

• Per Shelf =4.9 Amps.

Note that the worse case conditions under which

these parameters were measured include a 7,500 ft.

# 26 AWG loop, 60 mA. of CPE current, a fully

loaded 13 slot shelf, and a 42.5 V shelf battery

voltage.

7.11 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/sq. ft.

Section 150-611-103

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7.12 In Central Office locations, the maximum

power dissipation for open faced, natural

convection cooled mountings is limited to 120 W /

sq. ft. per Section 4.2.3 of the NEBS standard TR-

NWT-000063. The footprint of a 13 slot 23 “ HLU-

611 shelf is 7.024 sq. ft. Thus the maximum bay

dissipation is limited to 840 Watts. At 91 watts per

shelf, this limits the number of fully loaded HLU-611

shelves to 9 per bay. Note that this is a worse case

situation in that it assumes the entire Central Office

is subjected to the maximum power density.

Conditions other than these worse case ones would

permit increasing the number of shelves per bay

without jeopardizing the C.O.’s thermal integrity.

7.13 The thermal loading limitations imposed

when using the HLU-611 in CEVs or other

enclosures are determined by applying the HLU-

611’s power parameters to the manufacturer’s

requirements for each specific housing.

7.14 The Maximum Power Consumption is the

total power that the HLU-611 consumes or

draws from its -48 V shelf power source. This

parameter is needed when the 611 is located remote

to its serving C.O. It determines the battery capacity

required to maintain an 8 hour stand-by battery

reserve for emergency situations. It thus limits the

maximum number of plugs per remote enclosure.

Use the above data to perform this analysis on a

case by case basis.

HLU-611

DCE

FEMALE MALE

RD(RECEIVEDATA)

TD(TRANSMITDATA)

GND

DB9

DTE

TERMINAL

DB25

Figure 3. DB-9 Pin-outs.

7.15 The Maximum Current Drain is the

maximum current drawn from the shelf power

supply when it is at its minimum voltage (42.5 V).

This determines the shelf fusing requirements.

HLU-611 shelves are normally fused at 10 amps. A

fully loaded shelf of 13 HLU-611s draws 4.9 amps in

the worst case. This is well within the 10 amp fuse

limit.

7.16 A 9-pin (RS-232) DB-9 connector (see

Figure 3), is provided on the front panel.

This connector provides access to 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. 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 b/s.

7.17 The normally open alarm contacts available

across pins 20 & 21 comprise the HLU-

611’s minor alarm output. These alarm contacts

close for any of the following alarm conditions. Note

that the front panel message which accompanies

each alarm condition is shown in bold letters before

each alarm condition. Since more than one alarm

condition can exist at any given time but only one

message can be displayed, the alarms are listed in

their order of priorities. Only the highest priority

alarm is displayed if more than one alarm condition

exists.

1) ALRM LOSW: The VHDSL loop loses sync.

2) ALRM LLOS: Loss of the HLU T1 input signal.

3) ALRM RLOS: Loss of HRU T1 input signal

4) ALRM HES: VHDSL Loop has exceeded the 24

hour user-selected Errored-Seconds (CRC)

threshold

5) ALRM DS1: The total number of bipolar

violations (BPV) at the HLU and HRU T1 input

have exceeded the 24 hour user-selected

threshold.

6) ALM MAL: The margin on the VHDSL Loop has

dropped below the minimum threshold value set

by the dumb terminal MARGIN ALARM THRES;

as described in Section 8.

The HLU 611’s STATUS LED flashes RED for the

duration of a minor alarm condition. Alarms 4 & 5

can be inhibited by selecting NONE for the ESAL

Section 150-611-103

Revision 01

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system option. See Section 8 for System Settings

information. The MAL1 alarm can be disabled by

setting the margin alarm threshold to 0. All six

alarms can be inhibited by selecting DIS (disable) for

the ALM system option. The MNALRM can be

retired by executing the ACO option. This is

accomplished by depressing the SEL button on the

front panel. This turns the alarm off and replaces

the ALRM message by the ACO message. The

second part of the ALRM message, which defines

the cause of the alarm, remains. Both messages

remain until the alarm condition clears or another

alarm occurs. Disabling the ALM also retires an

ACO condition.

7.18 Pin 32, FUSEALARM, is driven to -48 V and

the front panel STATUS LED turns red

whenever the on board fuse opens.

7.19 The HLU-611’s front panel tri-color

STATUS LED has the following states:

• GREEN - Normal Operation

• FLASHING GREEN - VHDSL Acquisition

• FLASHING RED - Minor Alarm (For

conditions see Paragraph 7.17)

• RED - FUSEALRM

• YELLOW - Self Test in process or an HLU

loopback in effect (CREM or NLOC).

• FLASHING YELLOW - The HLU is in an

ARMED state.

7.20 Depressing both the MODE and SEL

pushbuttons on the front panel for at least 3

seconds initiates a MANUAL loopback session. This

session allows the user to SEL one of four HiGain

loopbacks. The message, MAN LPBK, appears on

the front panel display followed by the message

NRE?. If the SEL button is now depressed, an

NREM loopback is executed and the message

changes from NRE? to NREM. If the MODE button

is depressed instead of the SEL button, NRE? is

replaced by NLO?. This now allows an NLOC

loopback to be executed with the SEL button.

Depressing the MODE button two more times yields

the CLO? (CLOC) and CRE? (CREM) customer

loopback options. This interactive button procedure

permits any of the four HiGain loopback to be

executed. Once a loopback is executed, it can be

terminated and the next loopback option presented

by depressing the MODE button. If neither button is

depressed for a period of 30 seconds, this manual

loopback session terminates and the normal margin

displays reappear. If this time-out occurs with an

active loopback in effect, the appropriate loopback

message appears in addition to the loop margin

messages. Once the manual loopback session

terminates, the loopback remains in effect until it

times-out in accordance with the user LBTO setting.

It can also be terminated by re-entering the manual

loopback mode and selecting another loopback.

Only 1 loopback can exist at any given time.

Depressing both buttons, again for 3 seconds,

terminates any active loopback, ends the MANUAL

loopback session and returns the display to normal.

Note that the loopbacks can be also initiated from

the RS-232 maintenance port by choosing the

LOOPBACK MODE, option “D” from the MAIN

MENU. This displays the Loopback Menu, shown in

Figure 14, from which any of the four loopbacks can

be initiated.

8. OPTIONS

8.01 The HLU-611 contains a non-volatile RAM

which stores the system option settings. No

dip-switches or jumpers are required to set the HLU-

611 configuration. The options are set via

pushbuttons on the front panel, through the RS-232

interface, or from the NMA interface and are

retained if shelf power is lost or if the HLU-611 is

unplugged. Table 2 lists the HLU-611 option

settings. Note that only those options enclosed by

quotes can be set by the front panel buttons. All 14

options can be set via the front panel RS-232

maintenance part. Figure 8 illustrates the same

options on the HLU-611 set-up menu.

8.02 The SETUP (MODE and SEL) momentary

pushbuttons are used to set the options

from the front panel. To initiate an OPTION

SETTING mode, depress the MODE button for 1

second and release. The message displayed on the

front panel alternates between the system

parameter and its current setting. Depressing the

SEL button steps the display through all possible

settings (one at a time) of the MODE (parameter)

being displayed. After the desired setting has been

chosen, depress MODE. This does two things.

First it updates the current displayed mode to the

setting chosen. It then selects the next configurable

parameter. After the last parameter has been

selected, the displays shows CONF/NO. If the

MODE button is now depressed, none of the

changed parameters are installed. If the SEL button

Section 150-611-103

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is depressed, a YES message is displayed and the

chosen changes are installed. In either case the

display returns to its normal mode. The display also

returns to its normal mode, without installing any

new changes, if neither button is depressed for 30

seconds.

8.03 All 14 user options can be set to their

default values by depressing the SEL button

for 6 seconds. When released, the message: “DFLT

NO” appears. To install the default values depress

the SEL button again. The “YES” will follow

indicating that the default values are now in effect.

To terminate this DFLT mode without reverting the

options to their default values, depress the MODE

button or do nothing for 30 seconds. The latter

returns the display to its normal state.

8.04 Depressing the MODE button for 3 or more

seconds causes the display to scroll through

the HLU’s software version number, its List #, the

type of frame pattern being received from the DSX-

1, the line code setting of the HLU and all 11 option

settings. See Table 9 for these additional

messages.

8.05 The following three user options must be set

with a dumb or smart terminal: CIRCUIT ID,

DS0 BLOCKING and MARGIN ALARM

THRESHOLD.

8.06 The CIRCUIT ID option is set by choosing

the “I” option from the dumb terminal’s main

menu shown in Figure 6. The message “enter

circuit ID #: 24 characters max” follows the “I”

selection hit the return key after entering the chosen

set of alpha-numeric ID characters. Then chose “C”

to confirm. Note if more than 24 characters are

entered, en error message appears. Simply delete

the excess characters and then hit the return key

once again. The ID appears in all HLU screens as

shown in Figures 6 through 13. The ID does not

appear on the HRU screens when the maintenance

port is accessed at the remote unit. Note that the

Circuit ID is not set to its default (all blanks) setting

when the DFLT setting option is utilized.

8.07 To set the DS0 BLOCKING option first

select the SYSTEMS SETTINGS (“D” choice)

from the main menu. The menu shown in Figure 8

appears. Now enter the letter “B” shown in

parenthesis of the DS0 blocking selection. The DS0

channels are blocked or unblocked by entering each

channel’s number. Multiple channels can be

selected by inserting a space between each entry.

After all the new settings have been made, enter “E”

for exit and then “C” for confirm. The new choices

are now installed. If DS0 blocking is invoked in a

HiGain-2 system that has an earlier HRU that does

not support the blocking option, blocking will only

occur at the DS1 output of the HLU. The HRU’s

DS1 output will not be blocked. Also, all blocked

channels are opened for all HiGain-2 loopback tests.

This allows the standard full bandwidth T1 loopback

tests to be performed.

8.08 To set the MARGIN ALARM THRESHOLD

select “G” from the system settings menu.

Enter the desired minimum acceptable alarm

threshold from the 0 to 15 dB range. This causes a

minor alarm to occur (see Paragraph 7.17) if the

margin on the VHDSL loop drops below the selected

threshold value. Since the margin can never drop

below 0, choosing ”0” for the margin threshold turns

the margin alarm off.

8.09 The other dumb terminal system settings

are set in a similar manner. Simply enter the

letter in parenthesis of the parameter to be changed.

Each entry of this letter scrolls the parameter to its

next value, hit the enter key after each selection is

madeAfter all selections have been made, enter “E”

and then “C” to the resulting Confirm message. This

activates the new choices and returns control to the

main menu.

8.10 The SELF-TEST mode that occurs when the

VHDSL loop is not in sync includes the

input DS1 transceiver chip in the self test procedure.

This process can cause the AIS pattern, that is

normally transmitted from the HLU during these out

of sync intervals, to exhibit occasional BPVs.

9. LOOPBACKS

9.01 HiGain-2 has a family of loopback options.

The most important of these is the Smart-

Jack loopback which enables the HRU-612 to

respond to the standard 2/3 in 5 Smart-Jack in-band

loopback codes. This option can be enabled or

disabled from either the front panel settings or the

dumb terminal system settings menu.

9.02 In addition to the Smart-Jack loopback,

HiGain-2 can be configured for one of five

special in-band loopback command sequences.

These are selected from the SPLB user option

shown in Table 2 and Figure 8. The loopback

locations are shown in Figure 5.

Section 150-611-103

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9.03 GNLB is the HiGain-2 Generic loopback

code. The GNLB allows 4 in 7 or 6 in 7 in-

band codes to loop-up the HLU (NLOC or CREM

respectively) and 3 in 7 or 4 in 7 in-band codes to

loop-up the HRU (NREM or CLOC respectively).

NLOC & NREM are issued from the HLU DS1

interface. CLOC & CREM are issued from the HRU

DS1 interface. All looped states are terminated

(looped-down) with the 3 in 5 loop-down code. All

commands must be present for 5 seconds before

HiGain-2 responds. Table 3 lists the test

procedures that apply when using the GNLB mode.

Section 150-611-103

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TABLE 2. SYSTEM OPTION SETTINGS

MODE CHOICE DESCRIPTION

“EQL” EXT* Replaces the internal equalizer with a 12 Vpk-pk drive source for an external

equalizer.

0 Sets the Equalizer to DSX-1 for 0-133 feet.

133 Sets the Equalizer to DSX-1 for 133-266 feet.

266 Sets the Equalizer to DSX-1 for 266-399 feet.

399 Sets the Equalizer to DSX-1 for 399-533 feet.

533 Sets the Equalizer to DSX-1 for 533-655 feet.

LBPK DIS Configures the HiGain system to ignore all in-band Smart-Jack loopback

commands.

ENA* Enables the HiGain system to recognize all in-band Smart-Jack loopback

commands.

SPLB GNLB Configures the HiGain system to respond to the generic (3/4 in 7) in-band

loopback codes.

A1LB &

A2LB* Configures the HiGain system to respond to the Teltrend addressable repeater

in-band loopback codes.

A3LB Configures the HiGain system to respond to the Wescom addressable repeater

in-band loopback codes.

A4LB Configures the HiGain system to respond to the Wescom Mod 1 addressable

repeater in-band loopback codes.

A5LB Configures the HiGain system to respond to the Teltrend Mod 1 addressable

repeater in-band loopback codes.

PWRF DIS Disables powering to the HRU-612.

ENA* Enables powering to the HRU-612.

ZBTS ON Tells the HiGain system that the ESF frame is operating in its Zero Byte Time

Slot Interface (ZBTSI) mode.

OFF* Tells the HiGain system that the ESF frame is operating in its normal non-

ZBTSI mode.

ESAL 17 Creates a minor alarm condition which flashes the red STATUS LED when 17

Errored Seconds (ES) (17 HDSL CRC errors on either HDSL loop or a total of

17 BPV and FERR occur within a 24-hour period.

170 Creates a minor alarm condition which flashes the red STATUS LED when 170

ES (170 HDSL cyclic redundancy check (CRC) errors on either HDSL loop or a

total of 170 BPV and FERR) occur within a 24-hour period.

NONE* Prevents generation of a minor alarm due to excessive Errored Seconds.

“LBTO” 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 loopback to 60 minutes after initiation.

120* Sets automatic cancellation of all loopback to 120 minutes after initiation.

ALM DIS* Opens the Alarm relay contacts if closed, and prevents another relay alarm

closure from occuring.

ENA Enables activation of the minor alarm relay when a minor alarm condition

occurs.

Table continued on next page

Section 150-611-103

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TABLE 2. SYSTEM OPTION SETTINGS (CONTINUED)

MODE CHOICE DESCRIPTION

“LNCD” B8ZS Places both the HLU-611 & HRU-612 into their B8ZS modes.

AMI* Places both the HLU-611 & HRU-612 into their AMI modes.

“FRMG” AUTO* Configures the HiGain system to operate in an auto-framing (AUTO) mode in

which it continuously searches the input T1 bit stream for a valid SF or ESF

frame pattern. This feature is required for fractional T1 applications (DS0

blocking) where it insures proper channel time slot alignment. While the HiGain

system can also process unframed data in this AUTO mode, it is recommended

that the unframed (UNFR) mode be used for all unframed applications. Using

the AUTO mode for unframed applications runs the risk of detecting "pseudo-

valid” frame sequences, which can affect the data integrity.

UNFR Configures the HiGain system to operate in an unframed mode. This mode

disables the auto framing process and forces the HiGain system to function as a

transparent bit pipe.

HAIS DIS* Prevents a margin alarm from generating an AIS pattern at either TI interface.

Causes the HiGain system to transmit the AIS signal at both the HLU-611 &

HRU-612 T1 output ports when both of the HDSL loops are not in sync

(LOSW).

1LP Enables a margin alarm to initiate an AIS condition at each T1 output. Causes

the HiGain system to transmit the AIS signal at both the HLU-611 & HRU-612

T1 output ports when either of the two HDSL loops is not in sync (LOSW) or if a

MARgin alarm occurs.

SAIS ENA* Causes the HRU-612 to transmit the AIS signal towards the Network Interface

(NI) when in NREM or Smart-Jack loopback.

DIS Causes the HRU-612 to transmit the signal from the network towards the NI and

opens and terminates the HRU-612 RCV NI port when an HRU NREM or

Smart-Jack loopback is executed. The AIS signal is off.

CONF YES Confirms that all eleven (listed above) operating modes are to be updated to

their current choices.

NO* Prevents the most recently selected operating mode choices form being

updated. They remain as they were before the system option settings

procedure was entered.

MARgin Alrm

Trsh 0 to 15 dB The Margin Alarm Threshold can only be set via the RS-232 maintenance port.

It determines the minimum allowable margin below which a minor alarm can

occur.

4 dB* (Default value)

DS0 BLK The DS0 blocking option can only be set via the RS-232 maintenance port with

a terminal. The 4-Character HLU-611 front panel only displays the status of

the blocking option. BLK indicates at least one channel is blocked.

NONE* NONE indicates no channels are blocked.

“xxxx” Panel Set Only these options can be set by the front panel. All of the options can only be

set from the RS-232 maintenance port.

*Indicates HLU-611 factory settings. HiGain can be set to these default settings by pressing the SEL button for

6 seconds and then selecting the YES response to the resulting DFLT message.

Section 150-611-103

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9.04 The A1LB loopback selection (Table 4)

complies with that proposed for VHDSL

systems in the T1E1.4/92 recommendation with the

following additions:

1) Query loopback

2) IOR powerdown

3) Three loopback time-out choices

4) Initiation from either end

5) Repeating bit error signatures

6) Alternate Query loopback

These additions make A1LB identical to A2LB

described below. It is given a separate identity to

allow future T1E1 enhancements to be added

without affecting A2LB.

9.05 A2LB through A5LB are four special

addressable repeater loopback functions

which are supported by the List 6 version of

HiGain-2. These loopbacks provide HiGain-2 with

sophisticated maintenance and trouble shooting

tools. Tables 5 thru 8 list the details of these

Special Loopback (SPLB) functions. A2LB & A5LB

are patterned after the Teltrend addressable T1

repeater loopbacks. A3LB & A4LB are patterned

after the Wescom addressable T1 repeater

loopbacks. All four SPLBs have been enhanced to

handle the specific requirements of the following

HiGain-2 customers:

• A2LB (Teltrend) = Southwestern Bell

• A3LB (Wescom)=New England Tel.

• A4LB (Wescom Mod 1) =New York Tel.

• A5LB (Teltrend Mod 1) =Southern New

England Tel. (SNET)

9.06 A5LB differs from A2LB in that A5LB does

not block the arming ( 3 in 5) code from

exiting the HLU into the network. A2LB can be

configured to either block this arming code after 2

seconds, and replace it with the AIS code, or to

unblock it by executing the FAR-END ACTIVATE

code. Since A5LB never blocks the arming code

from exiting the HLU, it does not need this FAR-

END ACTIVATE code. A3LB differs from A4LB in

that A3LB supports the additional 1 in 6 smart jack

loopback command. Refer to the PairGain HiGain-2

Intelligent Repeater Application Note # 910 Part #

325-910-100 for more SPLB details.

9.07 When T1 loopback tests are performed on

the HiGain-2 system with 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 code is set to AUTO. This is caused by

the fact that in the AUTO DS1 code mode, the HLU &

HRU set their own code independent of each other.

Each end sets its transmit code to match its receive

code. Thus if one end is receiving AMI and the other

B8ZS, their codes are different. 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 HLU changes

to its B8ZS mode while 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

9.08 HiGain-2 may take longer than normal to

respond to inband loopback commands

when its framing mode is set to UNFR and the

inband commands are sent in either an SF or ESF

mode. The frame bits override the command bits

and cause errors in the command sequence. These

errors cause HiGain-2 to reject some sequences.

This can extend the detection interval.

C. INSTALLATION AND TEST

10. INSTALLATION

10.01 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.

10.02 The HLU-611 is designed to mount in a 220-

type ORB shelf or equivalent SXSS, Kentrox

T-Term and Wescom 342-30 shelves. The HLU-611

slot pin-outs are shown in Figure 4.

CAUTION

The ALM option must be disabled (DIS)

when using the Kentrox 220 T-Term shelf.

This is required to resolve a conflict

between the HLU alarm relay output and

the Kentrox external equalizer output. Both

use the same pins, 20 and 21.

Section 150-611-103

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Page 13

DS1TIP

DS1RING

DS1TIP1

DS1RING1

-48V

* FUSEALARM ISNO RM ALLYFLOATING ANDAT-48V

WHENACTIVATED

**M INORALARMCONTACTS(PINS20AND 21)ARE

NO RM ALLYO PEN AND CLO SEUPO N ALARM

FUSEALARM *

VHDSLTIP1

VHDSLRING 1

KEY

ALRM **

KEY

Figure 4. HLU-611 Pin-outs.

CAUTION

The HLU-611 is incompatible with the

newer Kentrox 224 shelves when these

shelves are optioned to connect their -V

line (which is normally -48V to -130V). The

-V line connects to pin 40. The HLU-231

connects pin 40 to 39 and pin 39 to -48V,

which causes the conflict.

11. TESTING

11.01 Tables 3 through 8 provide step by step test

procedures for the HLU-611 Unit as a

function of the loopback option selected. These

procedures allow verification of the integrity of the

VHDSL channel to the HRU-612 remote unit as well

as the DS1 channels to the customer and the local

DSX-1 interface.

11.02 The HLU’s 4 character front panel display

has many useful system diagnostic

messages. They are listed in Table 9. This display

turns on when power is initially applied to the 611.

In order to conserve power, it only remains on for 5

minutes if neither the MODE nor SEL buttons are

depressed. The use of either button restarts the 5

minute power-control timer.

11.03 If trouble is encountered on the DSX-1

interface, verify that the hit is making a

positive connection with the mounting assembly’s

connector. Also, verify that the pre-equalizer is

properly set. All installations should be set to the

largest value that does not exceed the distance from

the DSX-1 to the shelf

11.04 The transmit and receive T1 DSX-1 ports

have splitting access and bridging miniature

210 jacks as shown in Figure 2. Connecting one

cable between the two BDG jacks and another

between the two SPAN jacks splits the XMT and

RCV and creates metallic loopbacks towards both

the DSX-1 and the HLU.

11.05 Figure 7 shows the HLU status screen. It

contains useful information on the VHDSL

loops and the DS1 input. Figures 11, 12 & 13 show

the performance data & alarm history screens. All

the performance data shown in Figures 8 , 11 & 12

can be cleared to zero by selecting the (C)lear

option from the HLU Status Screen shown in Figure

7. Note that since the HLU is considered the master

module, this clears all performance data screens at

both the HLU & the HRU. Clearing the data from

the HRU only clears performance data at the HRU.

It does not clear it at the HLU.

Section 150-611-103

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TABLE 3. HLU-611 TEST PROCEDURES FOR GNLB OPTION

Step Action

1 Have the C.O. tester send the HRU (3 in 7) in-band loop-up for 5 seconds. Observe that the HLU

displays the “NREM” message indicating an HRU loopback is in effect (see Figure 5).

2 Have the C.O. tester transmit a T1 test signal into the HLU and verify that the returned (looped) signal is

error free.

3 If the above test fails, have the C.O. tester transmit the (3 in 5) in-band loop-down code. Verify that the

HLU display returns to normal.

4 Have the C.O. tester send the HLU (4 in 7) in-band loop-up for 5 seconds. Observe that the HLU

displays the “NLOC” message indicating an HLU loopback is in effect.

5 Repeat step “2”. If the test passes, the problem is in the cable pair or the HRU. If it fails, the problem is

in the C.O. equipment

6 The NREM and NLOC loopbacks can also be initiated from the front panel of the HLU with the MODE

and SEL pushbuttons. See Paragraph 7.20 for details.

7 The HLU can be looped-up from the remote location (CREM) by issuing the 6 in 7 command at the

HRU’s DS1 input port.

8 The HRU can be looped-up from the remote location (CLOC) by issuing the 5 in 7 command at the

HRU’s DS1 input port.

Figure 5. HLU-611 Loopback Configurations.

Section 150-611-103

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TABLE 4. HLU-611 TEST PROCEDURES FOR A1LB OPTION

Step Action

1 Send into the HLU the inband ARMING and NIU (Network Interface Hit) LPBK code 11000 for at least 5

seconds, or at least 4 repetitions of the 16-bit ESF Data Link ARMING code 0001 0010 1111 1111.

2 Monitor the output of the HLU-611 for the return of the pattern. Return of pattern indicates that either

the HRU has looped-up (If the SMART-JACK LOOPBACK option is ENABLED) or that an external NIU

has looped up (If the SMART-JACK LOOPBACK option is DISABLED) and that the HLU and HRU units

have been ARMED. Verify that the HLU display intermittently indicates ‘ARM and also “SMJK” if the

HRU is in loopback.. Also verify, if possible, that the LOOPBACK LED of the HRU-612 is flashing,

indicating that the HRU is armed or that it is on solid, indicating that it is both armed and in loopback.

3 Once armed the HLU can be looped back (NLOC in Figure 5) by sending IOR (Intelligent Office

Repeater) LPBK activation code 1101 0011 1101 0011 for at least 5 seconds. The tester observes the

following activation response:

• 2 seconds of AIS (all ones), followed by:

• 5 seconds of returning data pattern, followed by:

• 231 logic errors (including the frame bits) occur in the returned pattern(20 errors if ILR-2

were sent), followed by:

• normal looped data. Note that this error pattern will repeat every 20 seconds as long as the

IOR loopback pattern is

• being sent. This same 20 second repeat scenario also applies to ILR, Time-Out Override

and Query commands.

The HiGain-2 Line Hit is now in Logic Loopback (NLOC of Figure 5). The display on the HLU-611

periodically shows NLOC (network local loop) and ARM (the HLU is still armed) in addition to the margin

displays. The Loopback Time-out option, which is user settable to NONE, 20, 60 or 120 minutes,

determines the duration of this loopback unless it is overridden by the TIME-OUT OVERRIDE command

or a loop down command is sent. If the Time-out Override code 1101 0101 1101 0110 is received, the

“activation sequence” described in “3” above is repeated and the automatic timed expiration of the

loopback is inhibited. If this Time-out Override is sent, then the only way to loop the HLU down is to

issue the IR (Intelligent Repeater) LPDN (loopdown) code 1001 0011 1001 0011 or to issue the NIU

(Network Interface Hit) LPDN and Disarm code 11100. The automatic time-out timer is restored during

subsequent loopback sessions.

4 Upon completion, the tester sends IOR LPDN code 1001 0011 1001 0011 to loop-down the HiGain-2

Line Hit. The unit remains ARMED however, as indicated by the ARM message on the HLU-611 and

the flashing of the HRU-612’s LOOPBACK LED.

Table continued on next page

Section 150-611-103

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TABLE 4. HLU-611 TEST PROCEDURES FOR A1LB OPTION (CONTINUED)

Step Action

5 Using the following codes, a NETWORK tester can activate loopbacks NLOC or NREM or SMJK (if

enabled) shown in Figure 5. A CUSTOMER tester can activate loopbacks CLOC or CREM.

Addressable 1 (A1LB) Repeater Loopback Commands

ARMING or NIU LPBK (inband) Arming code 11000 11000..

ARMING or NIU LPBK (ESF Data Link) Arming code 1111(F)*1111(F)0100(4)1000(8)

IR LPDN or DISARM (inband) Disarming code 11100 11100..

DISARM (ESF Data Link) Disarming code 1111(F)1111(F)0010(2)0100(4)

IOR LPBK (NLOC & CREM 231 errors) HLU Loop up 1101(D)0011(3)1101(D)0011(3)

ILR-2 LPBK (NREM & NLOC 20 bit errors) HRU Loop up 1100(C)0111(7)0100(4)0010(2)

IR LPDN Loop down (HLU or HRU) 1001(9)0011(3)1001(9)0011(3)

IR QUERY LPBK Query loopback 1101(D)0101(5)1101(D)0101(5)

IR ALTERNATE QUERY LPBK Alternate Query loopback 1101(D)0101(5)1110(E)1010(A)

TIME-OUT OVERRIDE Loopback Time-out Override 1101(D)0101(5)1101(D)0110(6)

FAR END NIU ACTIVATE Unblock AIS & pass 2 in 5 1100(C)0101(5)0101(5)0100(4)

IOR POWER DOWN (HLU) Removes VHDSL line power 0110(6)0111(7)0110(6)0111(7)

Note: the left most bit arrives first in all 8 sequences. The detection algorithm functions reliably with a

random 10E-3 bit error ratio (BER) on the facility. The IOR POWER DOWN code must remain present

for the duration of the power down mode. When this code is removed, HiGain-2 returns to its normal

unlooped and unarmed state.* This is the HEX number for the 4 bit group.

6 After testing is complete, send the universal loopdown [IR (Intelligent Repeater) LPDN] code if the

system is to loopdown but remain ARMED. Send the disarm code 11100 if all the equipment is to be

looped down, disarmed and returned to normal operation. Note that the ARMED mode has an

automatic time-out of 120 minutes.

7 The NREM and NLOC loopbacks can also be initiated from the front panel of the HLU with the MODE

and SEL pushbuttons. See Paragraph 7.20 for details.

Section 150-611-103

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TABLE 5. HLU-611 TEST PROCEDURES FOR A2LB OPTION