ATL AM2048A OS User manual

AM2048A
USER GUIDE
ATL part no: 1/298/100/610
Issue 02 - Jan. 2003

The information in this document is confidential to
ATL Telecom Limited and may not be disclosed or
reproduced in whole or in part without their written
consent
© ATL Telecom Limited 2002
ATL TELECOM USER GUIDE
AM2048A ATL TELECOM USER GUIDE AM2048A 1
Note: The information contained in this document is supplied without liability
for errors or omissions.
ATL Telecom Limited reserves the right to make changes
to this document at any time without notice.
COMPLIANCE NOTES AND SAFETY INSTRUCTIONS:
Caution – Hazardous voltage inside the equipment
Safety Instructions:
This apparatus must be installed and maintained by
SERVICE PERSONNEL.
Disconnect Device Statement:
For the AM2048A AC versions the Mains Switch serves as the
disconnect device, therefore a socket outlet should be installed near the
equipment and be easily accessible.MING USING FRONT P
Power Rating Information – DC Version:
Voltage Range -40V to -72V
Maximum Current 170mA
Power Rating Information - AC Version:
Voltage Range 85Vrms to 250Vrms
Maximum Current 20mA
Frequency Range 50 - 60Hz
TTE – Network Safety Statements:
The AM2048A is a CLASS I product and USER SAFETY and the safety status of the Ports is
dependent upon the earth connection. If the MAINS EARTH or the DC EARTH cannot be
guaranteed to be a PROTECTIVE EARTH a PROTECTIVE EARTH conductor must be connected
to the M3 STUD on the REAR PANEL.
The copper DSL line connection has a safety status of TNV-3.
This is a RFT-C type power feed circuit and must only be connected to another circuit of the
same type.
PIM - G703 1/298/001 connected to an UNEXPOSED ENVIRONMENT;
Tx 75 Ohm BNC connection has a safety status of EARTHED SELV.
Rx 75 Ohm BNC connection has a safety status of UNEARTHED SELV.
120 Ohm 8 WAY RJ45 connection has a safety status of UNEARTHED SELV.
PIM - G703 1/298/001 connected to an EXPOSED ENVIRONMENT;
Tx 75 Ohm BNC connection has a safety status of EARTHED TNV-1.
Rx 75 Ohm BNC connection has a safety status of UNEARTHED TNV-1.
120 Ohm 8 WAY RJ45 connection has a safety status of UNEARTHED TNV-1.

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AM2048A 3
2.1 EXAMPLE APPLICATIONS 10
2.1.1 Desktop modem to desktop modem, no external timing 10
2.1.2 Desktop modem to desktop modem, with external timing 10
2.1.3 Desktop modem to desktop modem with split site working 11
2.1.4 Rack mount modem to desktop modem 12
4.1 CONNECTION OF PROTECTIVE EARTH 15
4.2 WARNING - DC POWERING DIRECT FROM EXCHANGE BATTERY 15
4.3 POWER ON SEQUENCE 15
4.4 DEFAULT SETTINGS 16
4.5 LOGGING ON 16
4.6 SETTING MASTER/SLAVE MODE 17
4.7 SETTING THE USER INTERFACE 18
4.8 SETTING THE NX64K USER DATA RATE 18
4.9 SELECTING THE CIRCUIT CONFIGURATION 19
4.9.1 Standalone Section 19
4.9.1.1 G.703 to G.703 Transparent Timing 20
4.9.1.2 G.703 to G.703 Internal Timing 20
4.9.1.3 G.703 to X.21/V.35 Internal Timing 21
4.9.1.4 X.21/V.35 DCE to X.21/V.35 DCE 22
4.9.2 Tandem Section – External Timing 22
4.9.2.1 X.21/V.35 DTE-to X.21/V.35 DCE 22
4.9.2.2 G.703-to X.21/V.35 DCE 23
4 INSTALLATION 15
3 CONSTRUCTION 13
2 INTRODUCTION 9
1 SCOPE 7
2ATL TELECOM USER GUIDE
AM2048A
PIM - X21 1/298/002 - 15 WAY D-Type connection has a safety status of EARTHED SELV.
PIM - V35 1/298/003 - V35 connection has a safety status of EARTHED SELV.
PIM - ePIM 1/298/004 -
10/100Base T - 8 WAY RJ45 connection has a safety status of UNEARTHED SELV.
USB - 4 WAY Type B connection has a safety status of EARTHED SELV.
Safety Status Classification of non network PORTS.
Mains Input - IEC320 - 85Vrms - 250Vrms 50/60Hz connection has a safety status of PRIMARY
CIRCUIT.
DC Input - 3 PIN MINIFIT - -40Vdc - -75Vdc connection has a safety status of TNV-2.
Management Port Interface - 9 WAY FEMALE D-Type connection has a safety status of
EARTHED SELV.
Definitions:
Exposed Environment
A TELECOMMUNICATIONS NETWORK is considered to be an exposed environment if one or
more conditions for an unexposed environment are not fulfiled.
Unexposed Environment
A TELECOMMUNICATIONS NETWORK is considered to be an unexposed environment if the
following conditions apply to all parts of the network.
a) The possible effect of indirect lightning has been reduced by measures described
in IEC 61312-1.
b) The possibility of having different earth potentials has been reduced by connecting all
equipment within the network to the same equipotential bonding system (see HD 384).
c) The possibility of power cross/contact has been reduced (see HD 384).
d) The possibility of induced transients and voltages has been reduced.
Caution – Electrostatic sensitive device
Electro-static discharge (ESD) Warning:
Antistatic precautions should be observed at all times.
If the unit is power fed from the DSL line interface then a functional
earth MUST be connected. (See Section 4 on Installation).
Manufacturers Declaration*
ATL Telecom Limited declares that this product is in conformity with the
essential requirements of the ‘R&TTE directive 1999/5/EC’.
* A copy of the Declaration of Conformity is available upon request from ATL
Telecom Limited.

4.9.3 Crossing an SDH Network 24
4.9.4 Crossing a PDH Network 24
4.10 G.703 OPTIONS 24
4.10.1 Impedance 24
4.10.2 Timing 25
4.10.3 Framing 25
4.10.3.1 Unstructured Operation 25
4.10.3.2 Structured Operation 26
4.10.3.3 Structured Working, CRCs Enabled 27
4.10.4 ETS 300 233 Loopbacks 28
31
6.1 END TO END DELAY 33
6.2 JITTER 33
6.3 TRANSMISSION RANGE 33
6.3.1 2-Pair Noise Free Range on 0.4mm Wire 33
6.3.2 1-Pair Noise Free Range on 04mm Wire 33
6.3.3 1-Pair With Noise Range on 04mm Wire 34
7.1 AC POWER INLET 35
7.2 DC POWER INLET 35
7.3 COPPER TRANSMISSION LINE 35
7.4 SERIAL CONTROL 37
7.5 INTERFACE MODULES 38
7.5.1 G.703 38
7 INTERFACES 35
6 TRANSMISSION PERFORMANCE 33
5 COMMISSIONING 31
4ATL TELECOM USER GUIDE
AM2048A
4ATL TELECOM USER GUIDE
AM2048A 5
7.5.2 X.21 39
7.5.3 V.35 40
7.5.4 e-PIM 41
7.6 Front Panel 42
7.6.1 Controls 42
7.6.1.1 Disabling the Front Panel Controls 42
7.6.1.2 Programming Mode 42
7.6.1.3 Resetting to Factory Default Configuration 43
7.6.1.4 Setting Loops 43
7.6.2 Indicators 44
8.1 G.703 PLUG IN MODULE 45
8.2 X.21 PLUG IN MODULE 45
8.3 V.35 PLUG IN MODULE 46
8.4 MOTHERBOARD 47
10.1 COPPER TRANSMISSION 53
10.2 DSL TRANSMISSION FRAME 54
10.3 CONTROL CIRCUIT 54
10.4 USER INTERFACE MODULES 55
11.1 TELECOMMUNICATION STANDARDS 57
12 GLOSSARY 59
11 COMPLIANCE NOTES 57
10 SYSTEM OVERVIEW 53
9 FREQUENTLY ASKED QUESTIONS 49
8 INTERNAL LINKS AND FUSES 45

11
APPENDIX C – PROGRAMMING-FRONT PANEL 69
APPENDIX B – ORDERING INFORMATION 67
APPENDIX A - X.21/V.35 CLOCK OPTIONS 63
6ATL TELECOM USER GUIDE
AM2048A
6ATL TELECOM USER GUIDE
AM2048A 7
This User Guide applies to the High Speed DSL product family, designed and manufactured by
ATL Telecom Limited in the U.K.. It provides guidance for installation and commissioning of the
products, as well as useful reference information.
For guidance on the use of the VT100 management port refer to the VT100 User Guide
(part no. 1/187/500/611).
For guidance on programming the e-PIM Bridge/Router module (where fitted) refer to the
e-PIM supplement to this manual (part no. 1/187/009/610).
1 SCOPE 1

8ATL TELECOM USER GUIDE
AM2048A ATL TELECOM USER GUIDE AM2048A 9
The modems provide synchronous communications at user data rates between 64kbps and
2048kbps over one or two twisted pair cables. The equipment has modular transmission and
user interfaces, which allows the equipment to be configured to meet many different
installation requirements. Both rack and desktop versions of all units are available. Desktop
units are AM2048A and rack mount units are AM2048B. This manual covers the desktop
units.
The standard version of AM2048 uses G.SHDSL TC-PAM line code. In special circumstances,
they may be suplied with 2B1Q or CAP line codes. The modem may be modified from one line
code to the other by software download.
The customer interface is provided via interchangeable plug-in modules. Separate interface
modules can be purchased in order to modify the units for operation with a different customer
interface at a later date.
The standard version comes with two transmission pairs equipped and may be configured to
operate using one or two pairs. A more economical single pair version is also available for
applications where the flexibility of two pairs isn’t necessary.
The AM2048 is available as a mains powered (85-250Vac) version , or a DC (-48Vdc) version
that can also be line powered.
The AM2048 can be easily configured via a VT100 dumb terminal or via the front panel
controls. For VT100 configuration, it is recommended to use a VT100 terminal emulation
program running on a notebook or palmtop PC (see FAQs for details about obtaining a VT100
emulator program). Using the menu system with on-line help should reduce the need to refer
to the handbook. The VT100 Management User Guide gives a full description of the menu
system.
Once configured, the operation of the AM2048 is totally automatic. In the event of line
disturbances or power failure, the data link is restored without operator intervention.
Chapter 4 (Installation) describes the basic set-up procedure and this should be read prior to
setting up any link.
Modifications to line cords and power supply leads are available for country specific
requirements. In such cases, the line cord pin-out may be different.
2 INTRODUCTION
2

10 ATL TELECOM USER GUIDE
AM2048A
2.1 EXAMPLE APPLICATIONS
The diagrams below illustrate some basic applications:
2.1.1 Desktop modem to desktop modem, no external timing
The circuit timing originates from the internal clock in the master, and is sent out to the
customer terminal at both ends.
2.1.2 Desktop modem to desktop modem, with external timing
For synchronous interfaces, the timing can be taken from the network and passed to the
customer’s terminating unit.
Network
Customer
Terminal
AM2048A AM2048A
G.703/X.21/V.35
1 or 2 copper pairs
Timing
G.703/X.21/V.35/10BaseT/USB
Master Slave
Customer
Terminal
Customer
Terminal
AM2048A AM2048A
G.703/X.21/V.35/10BaseT/USB
1 or 2 copper pairs
Master Slave
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AM2048A 11
2.1.3 Desktop modem to desktop modem with split site working
This is referred to as point-to-multipoint working. The G.703 interface at the master end must
use the G.704 frame structure. It may be used for providing two Nx64k circuits from one
2Mbps pipe.
Note: When operating in Point to Multipoint, the master unit always has a G.703 user
interface.
The slave units may be EITHER all G.703 OR all Datacom (any mixture of X.21, V.35 and ePIM).
Customer
Terminal
Customer
Terminal
AM2048A
AM2048A
Master
Slave
Customer
Terminal
AM2048A
Slave
G.703/X.21/V.35/10BaseT/USB
G.703
2

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AM2048A 13
FIGURE 3.1 DESKTOP UNIT
The desktop unit is housed in a grey non-flammable plastic case (UL94 rating V0).
The front panel contains 6 LED indicators, 3 push button switches with LEDs to indicate their
activation, and a management port interface.
LEDs
• Status
• Line 1
• Line 2
• User
• Master
• Test
Buttons (with associated LEDs)
• Local Loop
• Loop Back
• Rem Loop
Refer to section 7.6 for an explanation of the front panel controls.
Connectors
• Management port interface 9 way female D-type
atl
3 CONSTRUCTION
3
12 ATL TELECOM USER GUIDE
AM2048A
2.1.4 Rack mount modem to desktop modem
For customers with large installations at a central site, the DSL shelf is available to fit both 19”
and ETSI shelves, to help save space. The shelf holds 12 AM2048B rack mount cards. All of
the user interfaces available on the desktop unit are also available on the rack mount unit.
Network management is available by both SNMP over Ethernet (10BaseT) and the standard
VT100 system using a local terminal.
AM2048A
1 or 2 copper pairs
G.703/X.21/V.35/10BaseT/USB
Slave
SNMP Manager
12 x G.703/X.21/V.35/10BaseT/USB
DSL Shelf
RS-232 or
10BaseT
Customer
Terminal
AM2048B x 12

ATL TELECOM USER GUIDE
AM2048A 15
This chapter describes the basic steps that are required to set up a system using the DSL
Modem.
It is recommended that a pair of units is set up back-to-back and working correctly in the
desired operational mode before deployment.
4.1 CONNECTION OF PROTECTIVE EARTH
If it is required to connect the G.703 port to a circuit that is defined as TNV, then a protective
earth must be connected to the earth bond stud on the rear panel. See the Safety Statements
at the front of this User Guide.
If the unit is power fed then a functional earth must be connected to the earth bond stud on
the rear panel to provide a discharge path to ground for ESD protection. See the ESD warning
at the front of this User Guide.
4.2 WARNING - DC POWERING DIRECT FROM EXCHANGE BATTERY
If the installation requires that the –48V is referenced to earth (as opposed to using a floating
DC input) please ensure that the AM2048 is the special DC powered option.
Please refer to the order codes in Appendix B.
4.3 POWER ON SEQUENCE
With no DTE or line connected to the AM2048 on power up, the LED colour test sequence is
displayed (RED - GREEN - AMBER) followed by the self test indication as follows:
Prior to the sequence starting, a random pattern may appear momentarily.
User
Master
Test
Local
Loop
Loop
Back
Rem
Loop
RED
GREEN
AMBER
SELF TEST
INITIALISED
Green Flashing red
Status Line 1 Line 2
4 INSTALLATION
4
14 ATL TELECOM USER GUIDE
AM2048A
On the rear panel there are the following connectors:
Power input (depending on the model)
85 - 250 Volt mains socket IEC 320
–48V DC supply inlet socket 3-pin mini-fit
Line interface 8-way RJ45 (Copper)
Data Ports (depending on module fitted)
G.703 120 ohm 8-way RJ45
G.703 75 ohm BNC
X.21 15 way D-type female
V35 34 way MRAC female
10BaseT/100BaseT 8-way RJ45
USB USB type B (Slave)
The data interface connector type will be from one of the four user-specified interfaces
available. They are detailed in section 7.5. The plastic housing contains the main PCB.
The plastic case has an internal metallised layer for EMC screening purposes.
Also included is a 1.5m mains lead fitted with a country variant mains plug (mains models
only) and a 3 metre screened, stranded, Category 5 line cord terminated in 8-way RJ45 plugs
at both ends.
A VT100 Management connection cable is also available.
The overall dimensions of the unit are 274mm(L) x 251mm(W) x 55mm(H).

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AM2048A 17
Type the password, then press ‘Enter’ (note: the password is case sensitive). The default
password is carraige return.
The top-level menu system displays the sub-menus available.
For a full description of the menu system, refer to the ‘VT100 Management User Guide’.
4.6 SETTING MASTER/SLAVE MODE
The master unit is referred to as the ELU or Exchange Line Unit and the slave unit is referred to
as the NTU or Network Terminating Unit.
The ELU is a ‘master’ in several senses. The master end provides the source of the bit rate
timing for the transmission line(s). The ELU is also the ‘master’ from a network management
point of view. It contains the database of configuration information for itself and all connected
NTUs. The alarm and performance monitoring history is saved at the ELU. When the
management terminal is connected to the ELU it can read all of the information from the
remote NTU, whereas when the management terminal is connected to the NTU, only the local
information is obtainable.
It is possible to set Master/Slave by using the front panel buttons if a terminal is unavailable,
see section 7.7.1.
To change the setting using the terminal go to the “Configuration>Master/Slave” screen and
select the appropriate option. (Use the arrow keys or tab key to navigate and the space bar to
change the setting). The basic setup for all modes is as follows:
At the master end:
Configuration>Master/Slave
1 select Master
2 select Point-to-Point or Point-to-Multipoint, as appropriate
3 enable the required number of lines
4 select the required line rate
At the slave end:
The factory default setting should allow the units to get into sync, otherwise:
Configuration>Master/Slave
1 select Slave
2 select Point-to-Point or Point-to-Multipoint, as appropriate
3 enable the required number of lines
4 select the required line rate
The unit will automatically reboot with the new settings once the “return” key is pressed to
accept the changes. You will then be invited to log back on to the system.
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16 ATL TELECOM USER GUIDE
AM2048A
During sequence the available colours of each LED are displayed in turn as a confidence check.
When the LED confidence check is complete, the test LED flashes as the internal self-test
sequence is completed. The flashing will normally last for about 4 seconds, however, if a new
application has been loaded this time will be extended by about 10 seconds while a backup
copy of the application is made.
With no external connections the unit will sense the loss of external signals and raise the
appropriate alarms by illuminating the Line 1 LED in red (and Line 2 LED if the modem is
configured for two lines). The User LED may also be illuminated depending upon the type of
user interface fitted.
When the system has been installed and is working correctly the Status, Line 1, Line 2 (if
configured for 2 lines), User and Master (if configured as master modem) LEDs will be
illuminated in green and all other LEDs will be extinguished.
4.4 DEFAULT SETTINGS
The factory default is for the unit to be configured as a slave (NTU). For all modes of
operation, one unit must be set to master mode, while the other unit must be set to slave
mode. The front panel ‘Master’ LED indicates the mode of the unit.
The factory defaults have been chosen to allow the minimum configuration for most users.
The default number of transmission lines is two pairs.
It is possible to set-up the following without changing configuration.
Master Slave Comment
G.703 G.703 Unframed, transparent timing.
G.703 X.21/V.35 DCE
G.703 e-PIM
X.21/V.35 DCE X.21/V.35 DCE
X.21/V.35 DCE e-PIM
e-PIM e-PIM
For all configurations, the default user rate is 2048kbps.
4.5 LOGGING ON
Connect a VT100 terminal (or PC running a VT100 emulation program) to the 9-way serial
port on the front of the unit. Configure the serial port settings of the VT100 terminal to
19,200 baud, 8 bits, no parity, Xon/Xoff. The log on screen should appear automatically once
the AM2048 detects the terminal.
Type ‘C’ to select Configuration, then press ‘Enter’.

ATL TELECOM USER GUIDE
AM2048A 19
4.9 SELECTING THE CIRCUIT CONFIGURATION
The term ‘digital section’ refers to the data link between the user ports of the connected
AM2048s.
In a standalone section, the AM2048s provide the complete transmission system.
In a tandem section, the AM2048s are used to extend an existing circuit or network port.
To achieve synchronous data transfer, the master AM2048 must derive its timing from the
circuit to which it is connected.
A Point-to-Point link requires two AM2048s, one master and one slave.
A Point to Multipoint link can have up to three AM2048s, one master and two slaves.
The AM2048 at one end of the digital section is selected to be a Master (ELU), the remote
end(s) are selected to be slave(s) (NTUs).
For a tandem section, the AM2048 connected to the tandem section is configured as the master.
Please refer to the diagrams on the following pages.
4.9.1 Standalone Section
The transmission channel can be a single optical fibre, one or two copper pairs.
Key for following diagrams:
B
Clock Source
Buffer (Elastic Store)
Customer
Terminal
Customer
Terminal
AM2048A AM2048A
G.703/X.21/V.35/10BaseT/USB
1 or 2 copper pairs
Master Slave
4
18 ATL TELECOM USER GUIDE
AM2048A
4.7 SETTING THE USER INTERFACE
The unit automatically detects what kind of user interface is plugged in and displays the
appropriate screen in the “Configuration>User Port” screen.
For X.21 and V.35, DTE/DCE selection is carried out by moving the link header on the user
interface plug-in module. The software automatically senses the link setting and sets the unit
up accordingly.
To check the user interface and any link settings, using the terminal, go to the
“Information>System” screen, this will display which user interface has been plugged in,
and which mode it is in.
Once a unit is configured as an ELU, the expected interface at the NTU may be set, or by
default, the unit will auto-discover the NTU user port configuration after the line gets into
synchronisation.
4.8 SETTING THE Nx64K USER DATA RATE
For X.21 and V.35 the user port data rate may be set in increments of 64kbps. The data rate is
set by entering the desired value of N. The full range of N is from 1 to 32. The screen display
gives the equivalent data rate in kbps for the value of N. The default value of N is 32,
i.e. 2048kbps.
The AM2048 automatically restricts the maximum value of N to match the number of
transmission lines enabled and the transmission line rate selected in the
“Configuration>Master/Slave” screen.
The default value of N is 32.
Note: In a G.703 to X.21/V.35 configuration, if the G.703 interface is changed to structured
working, the maximum value of N at the X.21/V.35 interface is N = 31.
To change the user port data rate:
At the master end:
1 Configuration>User Port.
2 Set the desired value of N.
Press Enter to activate the change.

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AM2048A 21
The internal clock is generated at the Master, both terminals lock to this clock and return the
clock to the AM2048s. An elastic store in the AM2048 buffers the data.
Using the “Configuration > User Port” Menu:
1 At the Master, select the ‘Internal’ timing option.
2 Using F8, cycle to the NTU user port, select the ‘Internal’ timing option.
Press ‘Return’ to enter the changes.
4.9.1.3 G.703 to X.21/V.35 Internal Timing
Slave terminals are connected to the digital section at both ends, a clock inside the Master
then becomes the reference clock for the entire system.
The internal clock is generated at the ELU, both terminals lock to this clock and return the
clock to the AM2048s. An elastic store in the AM2048 buffers the data.
Using the “Configuration > User Port” Menu:
At the Master, select the ‘Internal’ timing option (There is nothing to set at the Slave).
Press ‘Return’ to enter the changes.
4.9.1.4 X.21/V.35 DCE to X.21/V.35 DCE
The terminals connected to the digital section at both ends are DTEs, a clock inside the ELU
then becomes the reference clock for the entire system.
AM2048
Slave
AM2048
Master
Terminal Terminal
B
B
G.703 G.703 V.35/X.21 V.35/X.21
DTE
DCE
4
20 ATL TELECOM USER GUIDE
AM2048A
4.9.1.1 G.703 to G.703 Transparent Timing
In this configuration, the terminals are the source of timing. One of the connected terminals
may act as a master, the other as a slave. However, both terminals could operate
independently or pleisiochronously.
Clocks T1 and T2 are independent of one another and are transported independently through
the DSL system.
Using the “Configuration > User Port” Menu:
1 At the ELU, select the ‘Transparent’ timing option.
2 Using F8, cycle to the NTU user port, select the ‘Transparent’ timing option.
Press ‘Return’ to enter the changes.
Note: This is the default timing option for G.703.
4.9.1.2 G.703 to G.703 Internal Timing
Slave terminals are connected to the digital section at both ends, the clock source inside the
Master then becomes the reference clock for the entire system.
G.703
AM2048
Slave
AM2048
Master
Terminal Terminal
G.703G.703G.703
B
B
G.703
AM2048
Slave
AM2048
Master
Terminal Terminal
G.703G.703G.703
T1
T2

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AM2048A 23
4.9.2.2 G.703-to X.21/V.35 DCE
Using the “Configuration > User Port” Menu:
1 At the Master, select the ‘Transparent’ timing option.
2 At the Slave there is nothing to select.
Press ‘Return’ to enter the changes.
V35/X.21
DTE
AM2048
Slave
AM2048
Master
Terminal Terminal
V35/X.21
DCE
G.703G.703
B
V35/X.21
DTE
AM2048
Slave
AM2048
Master
Network or
Terminal
Terminal
V35/X.21
DCE
V35/X.21
DTE
V35/X.21
DCE
B
4
22 ATL TELECOM USER GUIDE
AM2048A
4.9.2 Tandem Section – External Timing
For the following configurations, the modems are connected in series with another
transmission system or equipment that is the source of timing.
4.9.2.1 X.21/V.35 DTE-to X.21/V.35 DCE
In order to recover timing from the network, the plug in module at the master end of the
digital section must be configured as a DTE by unplugging the User Port Module and moving
the links as indicated on the PCB legend. See section 8.
Network
Customer
Terminal
AM2048A AM2048A
G.703/X.21/V.35
1 or 2 copper pairs
Timing
G.703/X.21/V.35/10BaseT/USB
Master Slave
V35/X.21
DTE
AM2048
Slave
AM2048
Master
Terminal Terminal
V35/X.21
DCE
V35/X.21
DCE
V35/X.21
DTE
B
B

ATL TELECOM USER GUIDE
AM2048A 25
4.10.2 Timing
For a full treatment of the timing options, see section 4.9.
4.10.3 Framing
4.10.3.1 Unstructured Operation
FIGURE 4.10.1: UNSTRUCTURED OPERATION
For unstructured working, Loss of Frame Alignment and AIS alarms are suppressed. The user
data passes transparently through the system. An arbitrary frame position is assumed for
mapping the user data in to the line pairs. The user data may or may not have TS0, and may
or may not be using CRC4.
To set up this configuration, go to the “Configuration > User Port” Menu and select
Rx Unframed (*)
Rx Framed ( )
Rx CRC4 [ ]
Tx TSO Transparent (*)
Tx TSO Generate ( )
Tx CRC4 [ ]
CRC4G
Tx
TS0 TS0
Rx
CRC4M
FAW
A
SA4
SA5
SA6
SA7
SA8
HDSL
CRC6
CRC4
CRC4M
Rx
FAW
A
SA4
SA5
SA6
SA7
SA8
TS0 TS0
Tx
CRC4G
FAW
A
SA4
SA5
SA6
SA7
SA8
HDSL
CRC6
NTU ELU
TE ET
TV3
FAW
A
SA4
SA5
SA6
SA7
SA8
4
24 ATL TELECOM USER GUIDE
AM2048A
4.9.3 Crossing an SDH Network
Both AM2048 sections take their timing from the network and both are configured the same.
Use the configuration shown in section 4.9.2.2.
Note: The SDH network might be configured to provide a PDH path, in which case see
section 4.9.4.
4.9.4 Crossing a PDH Network
In this example, a PDH network is shown where timing is passed transparently from end to
end in both directions. From a timing point of view, this is equivalent to connecting Master A
directly to Master B. To provide a Master clock to the system, side A should be set as in
section 4.9.1.3, otherwise, without a master clock somewhere in the path, the timing will be
unstable.
4.10 G.703 OPTIONS
4.10.1 Impedance
120Ω and 75Ωmay be selected under software control and set differently at each end of the
link. E.g. CO (Master) set to 120Ωand the CPE set to 75Ω. The factory default is for the
AM2048 to auto-detect which interface is being used. Once a signal has been detected on an
interface, the impedance parameter is then set so that after a power OFF-ON event the
impedance is selected immediately. The AM2048 may be set back to auto-detect at any time.
Connect the VT100 terminal emulator to the Master AM2048.
Go to the “Configuration>User Port” Screen to view/change the settings for the Master.
Use F8 to view/change the settings for the slave.
G.703/X.21/V.35/10BaseT/USB
Customer
Terminal
AM2048A AM2048A
G.703
Timing
Master
B
Slave
Customer
Terminal
AM2048AAM2048A
G.703
Timing
Master
A
Slave
PDH
Network
G.703/X.21/V.35/10BaseT/USB
G.703/X.21/V.35/10BaseT/USB
Customer
Terminal
AM2048A AM2048A
G.703
Timing
Master Slave
G.703/X.21/V.35/10BaseT/USB
Customer
Terminal
AM2048AAM2048A
G.703
Timing
MasterSlave
SDH
Network

ATL TELECOM USER GUIDE
AM2048A 27
4.10.3.3 Structured Working, CRCs Enabled
FIGURE 4.10.3: STRUCTURED WORKING, CRCS ENABLED
In this case, the CRCs are checked and errored blocks are indicated back across the user
interface by use of the E bits.
This is the least ambiguous mode of operation from a performance monitoring point of view
because each transmission section is covered by its own independent CRC check.
To set up this configuration, go to the “Configuration > User Port” Menu and select
Rx Unframed ( )
Rx Framed (*)
Rx CRC4 [X]
Tx TSO Transparent ( )
Tx TSO Generate (*)
Tx CRC4 [X]
In this mode of operation, the test loop activation messages defined in ETS 300 233 are
passed to and from the LT over the V3 interface.
CRC4
CRC4
NTU ELU
TE
CRC4G
Tx
TS0
Rx
CRC4M
CRC4G
Tx
TS0
Rx
CRC4M
HDSL
CRC6
CRC4G
Tx
TS0
Rx
CRC4M
CRC4G
Tx
TS0
Rx
CRC4M
HDSL
CRC6
ET
TV3
EE
E
E
FAW
A
SA4
SA5
SA6
SA7
SA8
FAW
A
SA4
SA5
SA6
SA7
SA8
FAW
A
SA4
SA5
SA6
SA7
SA8
FAW
A
SA4
SA5
SA6
SA7
SA8
4
26 ATL TELECOM USER GUIDE
AM2048A
4.10.3.2 Structured Operation
FIGURE 4.10.2: STRUCTURED WORKING, END-TO-END TRANSPARENT CRCS
To set up to monitor structured G.703 data, go to the “Configuration > User Port” Menu
and select
Rx Unframed ( )
Rx Framed (*)
Rx CRC4 [ ]
Tx TSO Transparent (*)
Tx TSO Generate ( )
Tx CRC4 [ ]
The incoming structured data may be set to monitor CRC4 errors by enabling the Rx CRC4
checkbox.. However, no E bits are returned at the user interface from the transmission
equipment.
For fractional working where the aggregate line rate is less than 2048kbps, Rx Framed is
selected automatically. When working fractionally, not all of the timeslots are transported from
one end of the link to the other; the G.704 frame is padded out with the programmable ‘Idle’
pattern. This can be set in the “Configuration>User Port” Screen.
CRC4
NTU ELU
TE
CRC4G
Tx
TS0
Rx
CRC4M
HDSL
CRC6
CRC4G
Tx
TS0
Rx
CRC4M
HDSL
CRC6
ET
TV3
EE
FAW
A
SA4
SA5
SA6
SA7
SA8
FAW
A
SA4
SA5
SA6
SA7
SA8
FAW
A
SA4
SA5
SA6
SA7
SA8
FAW
A
SA4
SA5
SA6
SA7
SA8
MON
MON

ATL TELECOM USER GUIDE
AM2048A 29
Table 2 Loop-back code definitions
These loop activation codes are only detected at the G.703 interface at the ELU when CRCs
are enabled.
Loop 1 is the equivalent of a local loop at the ELU.
Loop 2 is the equivalent of a remote loop set from the ELU.
Note: The specification did not anticipate point to multipoint so in this mode loop 2 is not
meaningful.
State
Loop-back 1
command
Loop-back 2
command
Loop-back
acknowledge
Loop-back release
command
DS-ET
<--
<--
-->
<--
Sa5
0
0
0
0
Sa6
1111
1010
xxxx
0000
4
28 ATL TELECOM USER GUIDE
AM2048A
4.10.4 ETS 300 233 Loopbacks
Loop 1 and Loop 2 may be activated by sending patterns using spare bits 5 and 6 in TS0.
Table 1 CrC4 Multi-frame Structure
Sub-
Multi-
frame
I
II
Frame
number
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Bits 1 to 8 of the PCM frame (i.e. time slot 0)
1 2 3 4 5 6 7 8
c1 0 0 1 1 0 1 1
0 1 A Sa4 Sa5 Sa61 Sa7 Sa8
c2 0 0 1 1 0 1 1
0 1 A Sa4 Sa5 Sa62 Sa7 Sa8
c3 0 0 1 1 0 1 1
1 1 A Sa4 Sa5 Sa63 Sa7 Sa8
c4 0 0 1 1 0 1 1
0 1 A Sa4 Sa5 Sa64 Sa7 Sa8
c1 0 0 1 1 0 1 1
1 1 A Sa4 Sa5 Sa61 Sa7 Sa8
c2 0 0 1 1 0 1 1
1 1 A Sa4 Sa5 Sa62 Sa7 Sa8
c3 0 0 1 1 0 1 1
E 1 A Sa4 Sa5 Sa63 Sa7 Sa8
c4 0 0 1 1 0 1 1
E 1 A Sa4 Sa5 Sa64 Sa7 Sa8
Multi-
frame
ELU NTU
Network
ELU NTU
Network
Loopback 1
Loopback 2

ATL TELECOM USER GUIDE
AM2048A 31
Once the equipment is correctly installed, it may be necessary to monitor the quality of service
before putting live traffic on the circuit, depending on the installation rules of the network.
The AM2048 has various features that help the user to do this with a high degree of
confidence without the use of extra test equipment. A terminal plugged into the ELU gives
access to the following information:
In the “Performance > M.2100” History screen, the display records errored seconds, severely
errored seconds and unavailable seconds for the aggregate line system. The recording interval
and the pass-fail criterion of the datalog record are programmable by the user to match the
tables found in ITU Recommendation M.2100.
In the “Performance > Transmission Line” screen, the display records G.826 statistics for both
ends of each transmission line. In a multi pair system, if errors are recorded in the M.2100
screen, this screen will help to locate the erroring line and direction of errors.
Once the circuit is working, the “Alarm > History” screen should be checked and cleared.
The alarm history should be checked after a suitable interval to ensure that no alarms are
occurring.
(For more details of the menu system see the “VT100 Management User Guide for the
AM2048.”)
5 COMMISSIONING
5
30 ATL TELECOM USER GUIDE
AM2048A

ATL TELECOM USER GUIDE
AM2048A 33
6.1 END TO END DELAY
The transit delay from one end of the system to the other is < 700uS.
6.2 JITTER
For G.703 interfaces, the jitter meets the requirements of TBR12 and TBR13.
These measurements are performed in the presence of the maximum tolerable input jitter.
6.3 TRANSMISSION RANGE
6.3.1 2-Pair Noise Free Range on 0.4mm Wire
6.3.2 1-Pair Noise Free Range on 04mm Wire
SPEED NOISE FREE RANGE ATTENUATION
2048kbps 4.4km 46.8dB @150kHz
1536kbps 4.75km 50.5dB @150kHz
1024kbps 5.3km 55.3dB @150kHz
768kbps 5.6km 59.9dB @150kHz
512kbps 6.2km 66.2dB @150kHz
SPEED NOISE FREE RANGE ATTENUATION
2048kbps 5.3km 56.4dB @ 150kHz
Measurement Filter Bandwidth Output Jitter
Lower Cut Off (High Pass) Upper Cut Off (Low Pass) UI Peak to Peak (maximum)
40Hz 100kHz 0.11
6 TRANSMISSION PERFORMANCE
6
32 ATL TELECOM USER GUIDE
AM2048A

35ATL TELECOM USER GUIDE
AM2048A 35
7.1 AC POWER INLET
AC power is fed via a standard 3 pin IEC socket. A power cord fitted with a country variant
mains plug is supplied with the unit. This should be plugged into a suitable power supply with
earth protection to provide ESD protection of the unit.
7.2 DC POWER INLET
DC power is fed in via the three-pin socket on the rear panel.
A connection from CGND to earth is required for ESD protection of the unit.
If the unit is line powered, the ground connection must be made to the earth bonding point
on the rear panel. (M3 stud).
Mating connector
Molex Minifit Junior Receptacle Molex Part Number: 39-01-4031
Molex female contact Molex Part Number: 39-00-0039
The DC Power Cable can be ordered from ATL, ATL Part Number (See Appendix B).
CABLE AM2048A DC POWER 6/910/000/423
1
2
-48V
0V
3CGND
2 13
7 INTERFACES
7
34 ATL TELECOM USER GUIDE
AM2048A
6.3.3 1-Pair With Noise Range on 04mm Wire
The AM2048 has been extensively tested for performance over a wide range of "with noise"
models with excellent results. The following are examples of these measurements to provide
general guidance to the performance quality.
These "with noise" measurements have been carried out with reference to, ETSI TS 101 524
V1.1.2 (2001-08), page 73, Table 12-3, Noise model C /ITU G.991.2 Annex B noise model C.
The physical lengths (L2) were used, to the nearest 50m, and the noise was increased until the
BER was in the order of 10-8. The results are as follows:
SPEED LENGTH (L2) of 0.4mm BER
2048kbps 2.15km 6.4x10-8
1536kbps 2.45km 3.4x10-8
1024kbps 3.05km 2.3x10-8
768kbps 3.4km 2.6x10-8
512kbps 4.2km 5.5x10-9
NOISE MARGIN
5.4dB
5.2dB
5.0dB
5.9dB
3.8dB

37
6
ATL TELECOM USER GUIDE
AM2048A 37
7.4 SERIAL CONTROL
A VT100 compatible terminal can be plugged into the 9-way D-type c6nnecter on the front
panel.
The socket is wired to allow a straight connection to a PC serial port. The serial cable must
have pins 2, 3, 4, 5 and 6 connected.
For a full description of the menu system, refer to the ‘VT100 Management User Guide’.
The serial port setting is 19.2Kbaud, 8 bits, no parity, 1 stop bit, and Xon/Xoff flow control.
The RS232C interface complies with the CCITT V24/V28 standards. The maximum length of
cable between communicating devices is limited to 15.2m (50ft).
Pin # Function
1
2 Receive cct. 104
3 Transmit cct. 103
4 DTR
5 Ground cct. 102
6 DSR
7
36 ATL TELECOM USER GUIDE
AM2048A
7.3 COPPER TRANSMISSION LINE
The line interface connector on the unit is an 8-way RJ45 socket.
The line cable supplied is a standard 3 metre screened Category 5 cable with an 8 way RJ45
plug on each end.
ATL part number 6/910/000/425 (See Appendix B).
1 32 4 65
PANEL VIEW
1
2
4
5
6
Line 1 A
Line 1 B
Line 2 A
Line 2 B
n.c.
n.c.
7 8 3
7
8
n.c.
n.c.