ASCOM AM 64/128EA User manual

High Speed Base Band Modems
Desktop Versions
a for faster transmission
USER GUIDE
Ascom part no:
1/265/001/610
Issue 02 – May 2001

1ASCOM USER GUIDE
High Speed Base Band Modems
The information in this document is confidential to
aTelecommunications Ltd and may not be
disclosed or reproduced in whole or in part without
their written consent
© aTelecommunications Ltd 2001
ASCOM USER GUIDE
High Speed Base Band Modems
Note The information contained in this document is supplied without liability
for errors or omissions.
Ascom Telecommunications 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:
1. This is a CLASS 1 product and must be connected to a safety earth
through its mains lead.
2. This apparatus must be installed and maintained by
SERVICE PERSONNEL.
3. Disconnect the mains plug and the NTP line connection before
attempting to change the Digital Network Interface card.
4. The mains plug on the equipment serves as the disconnect device,
therefore a socket outlet shall be installed near the equipment and
shall be easily accessible.
Power Rating Information –AC Source:
Voltage Range 110 –260V Wide ranging Switch Mode P.S.U.
Current Range 23mA at 230V and 48mA at 110V.
Frequency Range 50/60Hz
EN 41003 - Safety statements:
The NTP connection has a safety status of TNV-3, the Digital Network Interface port
connection and TERM port have a safety status of SELV and the mains connection has
an EXCESSIVE VOLTAGE status.

COMPLIANCE NOTES AND SAFETY INSTRUCTIONS 1
2.1 INTRODUCTION 9
2.2 EXAMPLE APPLICATIONS 10
2.2.1 Desktop modem to desktop modem with no external timing 10
2.2.2 Desktop modem to desktop modem with external timing 10
2.2.3 Desktop unit to Ascom rack system 10
2.2.4 Desktop unit to Ascom AM70 Multiplexer 11
2.2.5 Ethernet LAN to Ethernet LAN 11
3.1 FRONT PANEL 13
3.2 REAR PANEL 14
4.1 UNPACKING AND CONSIGNMENT CHECK 15
4.1.1 Ordering Information for Modems 15
4.1.2 Ordering Information for User Interface Modules 15
4.2 CONNECTING THE HIGH SPEED MODEM 16
4.3 CONFIGURING THE MODEMS 17
4.3.1 Desktop modem to desktop modem with no external timing 17
4.3.1.1 Configuring SLAVE unit 18
4.3.1.2 Configuring MASTER unit 18
4.3.1.3 Synchronisation 19
4.3.2 Desktop modem to desktop modem with external timing 19
4.3.2.1 Setting External Timing 20
4 INSTALLATION 15
3 UNIT FEATURES 13
2 SYSTEM DESCRIPTION 9
1 SCOPE 7
TTE - Network Statements:
Network connections for which the apparatus is compatible:
a) Analogue Baseband connection up to a rate of 1024kbps.
b) Digital X.21 connection up to a maximum rate of 1024kbps.
c) Digital V.35 connection up to a maximum rate of 1024kbps.
d) Digital X.21bis (V.24/V.28) connection up to a maximum rate of 19.2kbps.
e) Digital V.36 connection up to a maximum rate of 1024kbps.
f) Digital G.703 connection at a rate of 64kbps.
During EMC testing, the digital port cable used was of a screened type. To ensure
compliance, it is recommended that a screened cable be used on this port when in use.
Caution - Electrostatic sensitive device
Electro-static discharge (ESD) Warning:
DURING INSTALLATION DO NOT DISCARD ANY CONNECTOR
COVERS OR DUMMY PLUGS.
To ensure compliance with ESD criteria, ensure any port or connector
that is not in use is protected by the cover or dummy plug supplied.
Electrostatic precautions should be used at all times.
Manufacturers Declaration*
Ascom Telecommunications Ltd. 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 Ascom
Telecommunications Limited.
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4.3.3 Desktop unit to Ascom rack system 20
4.3.4 Desktop unit to Ascom AM70 Multiplexer 20
5.1 QUICK GUIDE TO BASIC FAULT FINDING 21
5.2 DEFAULT CONFIGURATION 22
5.3 LINK PERFORMANCE 22
5.3.1 Local Loop 22
5.3.2 Remote Loop 23
5.3.3 Far End Local Loop 23
6.1 SETTING THE CONTRAST ON THE LCD DISPLAY 25
6.2 MENU STRUCTURE 26
6.3 CONFIG MENU 27
6.3.1 Modem Mode 28
6.3.2 Number Of Line Pairs 28
6.3.3 Line Rate 28
6.3.4 Internal / External Timing 29
6.3.5 Interface Control Line Transfer 29
6.3.6 Transmit power 29
6.4 OPTION MENU 30
6.4.1 Interface Type / Info 30
6.4.2 Interface Settings 30
6.4.2.1 V.35 and V.36 31
6.4.2.2 X.21 bis (V.24/V.28) 31
6.4.2.3 X.21 31
6 FRONT PANEL MENU SYSTEM 25
5 TROUBLESHOOTING 21
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6.5 STATUS MENU 32
6.5.1 Unit Status 32
6.5.2 Alarms 33
6.5.3 Line Quality 33
6.5.4 Interface Status 33
6.5.5 Menu Locked/Unlocked 34
6.6 TEST MENU 35
6.6.1 Local Loop On/Off 36
6.6.2 Loopback On/Off 36
6.6.3 Remote Loop On/Off 37
6.6.4 V.54 Loop On/Off 37
6.6.5 Data Test 38
6.6.6 In-service Test 39
6.6.7 Lamp Test 40
6.6.8 Self Test 40
7.1 QUICK SET-UP GUIDE 41
7.1.1 Before you start 41
7.1.2 Procedure 41
7.2 VT100 REQUIREMENTS 42
7.2.1 Cable Assembly 42
7.2.2 Terminal Requirements 43
7.3 USE OF CONTROLS USING TERATERM 44
7.4 LOGGING IN 45
7.5 SCREENS 47
7.6 TEST COUNTS 48
7.7 CHANGING PASSWORDS 50
7 VT100 SYSTEM CONTROL 41
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This manual covers the installation and operation of the following Ascom high-speed base
band modems:
AM 64/128EA
AM 64/384A
AM 64/512A
AM 64/768A
AM 64/1024A
This guide includes explanations of the associated plug-in user interface modules with the
exception of the ABR (Ascom Bridge Router) module, which requires an additional guide
(part number 1/269/001/610).
Rack mount versions of the High Speed Base Band Modems are covered by the User Guide for
the associated shelf:
Shelf Type User Guide Part Number
AM Rack 1/113/002/610
AM Modem Shelf With Management 1/159/001/610
1 SCOPE 1
8.1 X21 (V.11) 51
8.1.1 15 Way D-type X.21 (V.11) Connector pin allocation 51
8.1.2 Module Link Settings 51
8.1.3 External Timing 52
8.2 X.21 BIS (V.24/V.28) 53
8.2.1 25 Way D-type X.21 bis (V.24/V.28) Connector pin allocation 53
8.2.2 Module Link Settings 53
8.2.3 External Timing 53
8.3 V.35 54
8.3.1 V.35 (MRAC) Connector Pin Allocation 54
8.3.2 Module Link Settings 55
8.3.3 External Timing 55
8.4 RS530 56
8.4.1 25 Way D-type RS-530 Connector pin allocation 56
8.4.2 Module Link Settings 57
8.4.3 External Timing 58
8.5 X.21 BIS (V.36) 58
8.5.1 37 Way D-type V.36 Connector pin allocation 58
8.5.2 Module Link Settings 59
8.5.3 External Timing 60
8.6 G.703 CODIRECTIONAL 64K 60
8.6.1 9 Way D-type Connector pin allocation 60
8.6.2 Module Link Settings 60
8.6.3 External Timing 60
8.7 ASCOM BRIDGE ROUTER 61
8 USER INTERFACES 51
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2.1 INTRODUCTION
All versions of the High Speed Base Band Modems provide synchronous communication of
data over twisted copper pair(s).
The AM64/128EA unit operates at 64Kbps and 128Kbps over a single pair.
The AM64/384A unit operates from 64Kbps to 384Kbps over a single pair.
The AM64/512A unit operates from 64Kbps to 512Kbps over a single pair.
The AM64/768A unit operates from 64Kbps to 768Kbps over two pairs.
The AM64/1024A unit operates from 64Kbps to 1024Kbps over two pairs.
Throughout the document, reference will be to “single pair”and “two pair”modems.
Wherever the term “single pair modem”is used, it applies to any of the following:
AM64/128EA, AM64/384A, AM64/512A.
Wherever the term “two pair modem”is used, it applies to the following:
AM64/768A, AM64/1024A.
The modems optimise their transmission characteristics for each line rate so a reduction in the
data rate will enable transmission over a greater distance.
They can be easily configured from either the front panel controls or a VT100 terminal, and
are available in a range of user interface options. The interfaces currently available are:
•X.21 15-way D-type socket
•X.21 bis 25-way D-type socket
•V.35 34-way MRAC socket
•V.36 37-way D-type socket
•RS.530 25-way D-type socket
•G.703 (64kbps 120ohm ) 9-way D-type socket
•Ascom Bridge Router with10BaseT 8-way RJ-45 socket
2 SYSTEM DESCRIPTION
2
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2.2.4 Desktop unit to Ascom AM70 Multiplexer
This arrangement connects the modem via the AM70 multiplexer on towards a network.
2.2.5 Ethernet LAN to Ethernet LAN
With the Ascom Bridge Router fitted, the modems can provide a WAN connection between
two Ethernet LANs via a 10BaseT port. Full routing and Network Address Translation
functionality precludes the need for external routing devices. In this mode, the timing
originates from the internal clock of the master.
1 or 2 copper pairs
master/slave modem master/slave modem
Ethernet LAN Ethernet LAN
Ascom AM-70
slave modem
Network
customer's
equipment
1 or 2 copper pairs
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2.2 EXAMPLE APPLICATIONS
The diagrams below illustrate some basic applications:
2.2.1 Desktop modem to desktop modem with no external timing
Either end of the link may be master, with the opposite end being the slave. The timing
originates from the internal clock in the master, and is sent out to the customer’s terminating
equipment.
2.2.2 Desktop modem to desktop modem with external timing
In this example the master modem accepts timing from the interface and uses this to time
the link.
2.2.3 Desktop unit to Ascom rack system
This system behaves like the above examples, but here one of the desktop units is replaced by
the Ascom rack, which can house 12 card units.
slave modem
master modem
customer's
equipment
customer's
equipment
1 or 2 copper pairs
V11, V24/V28, V35, V36,
RS530, 64K G703 1 or 2 copper pairs
master modem slave modem
V11, V28, V35,
V36, RS530
customer's equipment
sourcing timing
customer's
equipment
V11, V24/V28, V35, V36, RS530 1 or 2 copper pairs
master/slave modem master/slave modem
customer's
equipment customer's
equipment

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3.1 FRONT PANEL
Item Function
LCD Liquid Crystal Display. Modem displays menu system here.
Power LED Green LED is lit when unit is powered.
Fault LED Red LED is lit when unit is not in synchronisation (sync).
Test LED Red LED is lit when a loop is applied to modem, the modem is applying a
remote loop or the unit is running a data test.
Receive data LED Amber LED indicates the received data status of the transmission line.
Program LED Amber LED is lit when new configuration settings have been made but
not committed to memory.
Menu Select Buttons Right and Left arrow buttons scrolls menus in the LCD display.
Item Scroll Buttons Up and Down arrow buttons scrolls menu items on the LCD display.
Item Select Button Selects Item displayed on LCD display.
Program Button Stores changes made in configuration to memory.
MENU SCROLL SELECT PROG
POWER FAULT TEST RXD
ascom AM-64/512A
Liquid Crystal
Display Program
Buttons
Menu Select
Buttons
Item Scroll
Buttons
Item Select
Buttons
Power LED
Fault LED
Test LED
Receive
Data LED
Program LED
3 UNIT FEATURES
3
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4.1 UNPACKING AND CONSIGNMENT CHECK
The desktop version of the high speed modem comes packed complete with a 1.5m mains
lead fitted with a country variant mains plug, an RJ45 to RJ45 line cord and where necessary,
an RJ45 to BT style converter lead (where applicable).
Each modem comes with its appropriate user interface module fitted.
4.1.1 Ordering Information for Modems
The High Speed Base Band Modems product family can be ordered using the following
ordering number format:
1/265/YXX
Where Y refers to the model type:
Y=1 for AM64/512A
Y=2 for AM64/1024A
Y=3 for AM64/128EA
Y=4 for AM64/384A
Y=5 for AM64/768A
And XX refers to the user interface module fitted:
XX=01 for X.21 (V.11) interface
XX=02 for X.21bis (V.24/V.28) interface
XX=03 for V.35 interface
XX=04 for V.36 interface
XX=05 for RS530 interface
XX=06 for G.703 interface
XX=07 for modem without interface
4.1.2 Ordering Information for User Interface Modules
Replacement user interface modules can be ordered using the following ordering numbers:
X.21 (V.11) Interface Module 1/203/102/101
X.21bis (V.24/V.28) Interface Module 1/203/202/101
V.35 Interface Module 1/203/302/101
V.36 Interface Module 1/203/402/101
RS530 Interface Module 1/203/402/101
G.703 Interface Module 1/203/602/101
ABR 10BaseT 8-way RJ-45 socket 1/269/001/101
4 INSTALLATION
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3.2 REAR PANEL
Item Function
Line Connector RJ45 socket for connecting modem to copper lines
User Interface Plug in user interface board
Mains Connector IEC type connector for mains power
VT100 Terminal Connector 9 way D-type connector for RS232 connection to VT100 terminal
Line Connector
User Interface
Mains Connector
VT100 Terminal
Connector

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Your modem should now be connected as illustrated in the following diagram:
4.3 CONFIGURING THE MODEMS
4.3.1 Desktop modem to desktop modem with no external timing
A modem to modem link (as in diagram 2.2.1) requires a straight through connection, i.e. pair
one of the first modem connects to pair one of the second modem. If using two pair modems
in their two pair mode, the second pair of each modem should also be directly connected.
The units will not operate if the pairs are crossed over.
One end of the link will need to be configured as a MASTER and the other end will be
configured as SLAVE. The difference being that the master unit can download the major
settings to the slave, and not vice versa.
The downloaded settings are: number of pairs, line rate, and control line transfer. All other
settings are not downloaded, and have to be set locally.
Copper Pairs Interface Cable
(not supplied) Mains Connection
(supplied with correct plug)
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4.2 CONNECTING THE HIGH SPEED MODEM
Connect the mains lead into the IEC type socket on the rear of the unit and plug the other
end into an earthed mains supply.
WARNING! This unit must be used only with power supplies providing a safety earth.
The unit should power up, the following messages will be displayed:
Displays type and version of software
This will depend on the status of the unit
Plug one end of the RJ45 to RJ45 line cord lead into the RJ45 line connector socket on the
rear of the unit. The other end connects to your copper line pairs. For the RJ45 connector pair
one is on pins 7 and 8 and pair two (on two pair modems only) is on pins 4 and 5. In the UK
connection is made via RJ45 to BT style converter, connections on pins 1 and 6 for pair one
and 2 and 5 for pair two.
RJ45 TO BT STYLE CONVERTER RJ45 PLUG
A suitable lead is required to connect the modem user interface connector on the rear of the
unit to your DTE equipment. For details of interface connector pin-outs see section 8.
Pin 1
Pin 1

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•Press the SCROLL DOWN button once. The LCD will indicate the line rate, e.g. 512K:
•Press the SELECT button until the desired rate appears.
•Press the PROG button to implement your settings. The PROGRAM LED will go out.
This confirms the changes have been made to set the modem to MASTER, at the
specified data rate and in the case of the two pair modem, with either one or two pairs
in operation.
4.3.1.3 Synchronisation
If unconnected the modems should now show the message:
The green POWER LED and the red FAULT LED should also be lit.
If the modems are connected then, after approximately a minute the red FAULT LED should go
out and the LCD should show:
The modems are now synchronised and transmitting data to one another.
4.3.2 Desktop modem to desktop modem with external timing
This configuration is similar to the previous configuration. The MASTER modem however can
be set to receive an external clock source (see diagram 2.2.2). For X21 there is an additional
option of synchronising to an external byte (octet) timing signal.
Note that the user interface connector on the rear of the unit is wired such that the modem is
a DCE (Data Circuit-terminating Equipment). If the modem is required to act as a DTE (Data
Terminating Equipment) then a changeover cable will be required. The details are given in
section 8.
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With your modems connected as described above, the configuration procedure is as follows.
4.3.1.1 Configuring SLAVE unit
•Press MENU LEFT and MENU RIGHT buttons until the LCD shows the message:
•Immediately press the SCROLL DOWN button once or wait for three seconds. One of the
following messages will appear:
•If the message
is already displayed then your Modem is configured correctly for slave operation.
•Otherwise press the SELECT button until the LCD shows the message:
The PROGRAM LED will be lit to show that a change has been made but not yet programmed
into the memory.
•Press the PROG button to implement the SLAVE mode. The PROGRAM LED will go out
and your modem will now be configured as SLAVE.
4.3.1.2 Configuring MASTER unit
•Repeat the above section, but instead select the master mode:
•Press the SCROLL DOWN button once. If you have a two pair modem you can now select
one or two pair working by pressing the SELECT button, e.g. for 1 pair:

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5.1 QUICK GUIDE TO BASIC FAULT FINDING
No. Symptom Possible Fault Corrective Action
1 Power LED does Blown fuse. Replace fuse in mains lead.
not light.
2 Power LED lights Contrast adjustment is Check the screen contrast adjustment as
but LCD screen wrongly set. described in section 6.1.
information is
either missing or
of poor visibility.
3 Modems do not Configuration of Check configuration as detailed in section 4.3.
synchronise. modems incorrect. If modems set to independent mode check that
the configuration of each end matches.
Check that settings have not reverted to
default (see section 5.2).
Lines not correctly Check that line pair(s) are correctly connected
connected. together (not crossed).
Line attenuation or Select a lower data rate.
line noise too high.
External timing Check external timing signal quality,
signal incorrect. and cable assembly.
Check configuration (Section 4.3.).
Internal fault. Return unit for repair.
Verify by running self
test. (Also reported with
line rate / pairs = 0).
4 Modems Line attenuation or Select a lower data rate.
synchronised but line noise too high.
high error rate. External timing Check external timing signal frequency
signal incorrect. and quality.
Short line. Switch transmit power to 7.5dBm setting.
5 Modems Test loop active. Ensure no tests active at either modem.
synchronise but Interface control Check control lines relevant to interface and if
no data transfer. lines incorrect. necessary set the to “on”. e.g for V.28 circuits
108 and 105 should be on for data transfer.
If the lines are not used a range of clamping
operations are possible. See section 6.4.
5 TROUBLESHOOTING
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4.3.2.1 Setting External Timing
•Select the CONFIG MENU.
•Press the SCROLL DOWN button four times. One of the following messages will appear:
•Press the Select Button until the required timing mode is displayed.
•Press the PROG button to implement your setting. The modem is now configured for
external timing.
4.3.3 Desktop unit to Ascom rack system
The AM Rack (and MSM Rack) is a high-density 19”DIN41494 rack that allows 12 card style
modems to be housed together. The rack modems can be configured either as MASTER or
SLAVE units, though it is usual to have the rack based modems as MASTER units and the
desktop unit as SLAVE. Configuration of your desktop modem to work with a rack unit is as
described in sections 4.3.1.1 and 4.3.1.2.
4.3.4 Desktop unit to Ascom AM70 Multiplexer
The AM70 is a primary level flexible multiplexer housed in a 19”rack. It is possible to integrate
High Speed modems into the AM70 network by using HIRAC cards. The HIRAC card can
support five 512K channels and is always configured as a MASTER unit. To link your modem
to a HIRAC you must configure it as a SLAVE unit this is described in section 4.3.1.1.
This arrangement also allows the interface options to be downloaded, (in addition to the
configuration settings).
For details of the configuration settings at the multiplexer, please refer to the AM70
documentation.

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5.3.2 Remote Loop
With a BERT still connected as above, turn off the local loop and apply the remote loop.
The remote loop loops data back to the user interface from the far end modem as shown
below, thus this test can be used to check the integrity of the line.
There should be no errors or a very low error rate. If the error rate received is too high for your
application, try a lower data rate. When you have completed this test, turn off remote loop.
If a BERT is not available then the test can be carried out by using the in-built data test.
For details on how to do this see section 6.6.5.
5.3.3 Far End Local Loop
If the two tests above have been performed then also perform test 5.3.1 (local loop) on the
far end modem. This can only be performed when the far end modem is local to the operator.
Interface
Transmission
System
Interface
BERT
remote loop selected from this modemloop applied here
Transmission
System
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5.2 DEFAULT CONFIGURATION
The modem has a default configuration, and reverts to this when:
(1) The interface module has been changed.
(2) The stored configuration has become corrupted. This could occur if power was lost when
the configuration was being stored.
The modems signify the use of the default configuration by turning the program LED on after
the unit has powered up.
The default configuration is:
Modem mode: Slave
Number of line pairs: 1
Line rate: 64k
Internal / external timing: Line Clock
Interface control: Controls EOC
Transmit power: Auto
In the interface menus:
All clamps OFF, except, for V.35, V.36, and RS530 only:
Circuit 108 Set On
5.3 LINK PERFORMANCE
The high-speed modem has a number of features to aid in the testing of the data link.
To check a data link the following tests can be performed. Some of the tests outlined will
require the use of a Bit Error Rate Tester (BERT).
5.3.1 Local Loop
With a BERT connected to the user interface a local loop will loop data back to the user
interface as shown below. If everything is ok, no errors should be detected i.e. the user
interface is correctly transporting data.
Interface Interface
Transmission
System BERT
local loop applied in this modem
Transmission
System

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FRONT PANEL MENU SYSTEM
The front panel menu system allows you to make all the necessary changes to configuration
and set up via the front panel buttons and liquid crystal display. You can navigate between
menus using the MENU LEFT and MENU RIGHT buttons, and navigate between items in each
menu by using the SCROLL UP and SCROLL DOWN buttons.
Items in all the menus can be chosen using the select button. Items in the TEST menu become
active as soon as they are selected.
Items in the OPTION and CONFIG menus become active only after the PROG button is pressed,
and new items selected in these menus are highlighted with an * until this time. Several items
may be changed, and then programmed in one operation. Note that changes will be discarded
if the menu is exited or the unit is left idle for 1 minute.
If changes have been made an extra item Program Items will appear at the bottom of the
menu (Config and Options only). Selecting this has an identical effect to pressing the
program key.
6.1 SETTING THE CONTRAST ON THE LCD DISPLAY
The contrast of the LCD display can be adjusted to suit the ambient lighting conditions. If it’s
difficult to read the LCD display, follow the following procedure to adjust the contrast setting
for optimum visibility:
Press the MENU LEFT, MENU RIGHT and SCROLL UP keys simultaneously to show the contrast
control screen:
Use the SCROLL UP or SCROLL DOWN key to cycle through the 8 contrast values until
optimum visibility is obtained.
Press the SELECT key to leave this screen and store the selected contrast setting.
6 FRONT PANEL MENU SYSTEM
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6.3 CONFIG MENU
The configuration menu contains the items that define the set-up and mode of operation of
the modem.
Modem Mode
Number of Line
Pairs
Line Rate
Internal/External
Timing
Interface Control
Line Transfer
Transmit Power
Cannot be changed if
slave Mode
Rate can be from 64K to 1024K in
steps of 64K
(depending on modem type)
Cannot be changed in Slave Mode
Master Mode cannot select
Line Clk
External Byte clock no longer used
Slave Mode is always set to
Line Clk
Cannot be changed if
Slave Mode
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6.2 MENU STRUCTURE
The items in each menu are as shown below:
There are two inactivity timeouts in the menu system. Three seconds after selecting a menu
heading the first option of that menu will be shown. The display returns to the status menu
when the unit has been idle for 1 minute. Changes made to the configuration and not
programmed will be lost in this case.
Status Menu Test Menu Option Menu Config Menu
Unit Status Local Loop
On/Off Interface Type
Modem Mode
Alarms Loopback
On/Off Interface Info
Number of
Line Pairs
Line Quality Remote Loop
On/Off Interface Settings
Line Rate
Interface Status V54 Loop
On/Off
Internal/External
Timing
Menu Locked/
Unlocked Data Test On/Off Interface Control Line Transfer
In Service Test Transmit Power
Lamp Test
Self Test

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This wide choice of data rates allows the link to be set for optimal operation, the lower speed
rates allowing transmission over higher attenuation cables.
Note: any modem fitted with a G703 interface can only be set to 64k.
6.3.4 Internal / External Timing
If a modem is configured as MASTER then you also have the option to synchronise the modem
to an external clock. This allows your master modem to be set-up as a DTE. Note DTE set-up
will also require a switch over cable to configure the user interface connector in a DTE mode,
see section 8.
The G.703 interface is always configured for external bit timing.
6.3.5 Interface Control Line Transfer
The status of the user interface control lines can be communicated to the far end.
The control lines interchanged are:
X.21 V.11 - C circuit at local end to I circuit at remote end
(and vice versa)
X.21 bis V.28 / V.35 / V.36 / RS530 - circuit 105 at local end to circuit 109 at remote end
(and vice versa)
• Controls Off. This disables the transfer of control line information.
•Controls EOC. This sends the control line information by embedding the data into the
modems frame structure. This outband method is slowest but has no restricting effect on
the user bandwidth.
•Controls T/S. This allocates a 64k time slot in the transmitted data for transfer of control
information, and hence this 64k time slot is no longer available to the user. This inband
technique is fast but it does restrict the user rate by 64k. If this option is selected then the
maximum data rate will not appear in the list of choices, conversely, if the maximum data
rate is selected then this item will not appear here.
6.3.6 Transmit power
The modem can have two power settings:
•Auto. This is the normal mode of operation the modem transmits 13.5dBm of power into
a 135 ohm load.
•Power 7.5dBm. This is a low power setting to be used if problems are experienced on
short lines of less than 1 Km.
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6.3.1 Modem Mode
When two modems are connected together to form a link one end must be configured as
SLAVE and the other as MASTER. The major configuration settings set at the MASTER modem
will be downloaded to the slave during synchronisation.
The modems can be set to IND SLAVE (independent Slave) and IND MASTER. Here the
configuration is not transferred between the modems, and must be setup individually.
Using independent modes will result in a faster sync up process; but at the expense of
flexibility in having to set up both ends of the link.
The G703 interface can only be MASTER or IND MASTER.
6.3.2 Number Of Line Pairs
If you have a two pair modem you have the option of selecting between one and two pair
operation. If one pair operation is selected you will be restricted to a maximum data rate of
512kbps. If two pair operation is selected then higher data rates up to 1024kbps are available
(depending upon the model). The single pair modems and any modem with the G703
interface fitted allow one pair operation only.
When two pairs are selected each pair carries half of the data, thus a 256kbps link will
consist of two 128kbps lines and so a performance advantage is gained over a single pair
256kbps link.
6.3.3 Line Rate
The modem can be set to operate at the following rates:
Data Rate Modem Type
64K AM64/128EA, AM64/384A, AM64/512A,
128K AM64/768A, AM64/1024A
192K AM64/384A, AM64/512A, AM64/768A,
256K AM64/1024A
320K
384K
448K AM64/512A, AM64/768A, AM64/1024A
512K
576K AM64/768A, AM64/1024A
640K
704K
768K
832K AM64/1024A
896K
960K
1024K

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6.4.2.1 V.35 and V.36
For these interfaces the following options are available:
•105 Set On. Clamps line 105 permanently ON.
•106 Delay. Causes line 106 to follow 105 after a delay of about 20mS
•107 Set On. Clamps line 107 permanently ON.
•108/1 Set On. Clamps line 108 permanently ON.
6.4.2.2 X.21 bis (V.24/V.28)
For this interface the following options are available:
•105 Set On. Clamps line 105 permanently ON.
•106 Delay. Causes line 106 to follow 105 after a delay of about 20mS
•107 = 108/1. Causes 107 to follow the condition of 108.
•108/1 Set On. Clamps line 108 permanently ON.
6.4.2.3 X.21
For this interface the following option is available:
•C Set On. Clamps C circuit permanently ON. 6
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6.4 OPTION MENU
The option menu relates to items that are specific to each interface module.
6.4.1 Interface Type / Info
The first two lines of the display describe the interface type fitted to the modem. For the G703
case there is only the one line.
6.4.2 Interface Settings
The next few menu items give the interface control line options. The default control line
activity is displayed as follows:
e.g. Circuit 105:
if the clamp is applied:
Interface Type
Interface Info
Interface Settings Interface dependent settings

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•Receive Data. Modems synchronised and far end control signals are on, local end are off.
•Send Data. Modems synchronised and local control signals are on, far end are off.
•Data Transfer. Modems are synchronised and control signals are on at both ends of link.
6.5.2 Alarms
This read only display gives modem alarm information.
•No Alarm. There are no alarms present.
•No Sync. The modem is not synchronised with the far end.
•CRC Error. An in service test is running and CRC errors have been detected.
This alarm message is displayed for 5 seconds only unless the errors persist.
•LOS / CD Fail. For G.703 only:
LOS refers to loss of sync on the copper pair side.
CD Fail refers to Carrier Detect fail on the G.703 side.
6.5.3 Line Quality
This read only display gives an indication of the signal quality on the copper pair(s). A value of
0 indicates the units are not synchronised. The line quality is high (high signal to noise ratio) if
the value is 10 and the line quality is low (low signal to noise ratio) if the value is 1.
This display also gives an indication as to the progress of any start up sequence. When the
unit is trying to synchronise it will display a series of asterisks. The sequence starts with one
asterisk, and ends with four asterisks (on each pair) indicating full synchronisation.
6.5.4 Interface Status
This read only display shows the status of the interface control lines. The control lines
displayed will depend upon the interface selected.
e.g. Circuit 105:
For the X.21bis circuits there is also a composite display showing all of the control lines on one
line of the LCD. Here each circuit is represented by its last digit and the on state is denoted by
a filled in block.
e.g. 105,106,107,108,109 ON, 140,141,142 OFF:
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6.5 STATUS MENU
This menu displays alarm information to indicate the operational state of the modem.
6.5.1 Unit Status
This read only display gives an indication of the overall state of the data link.
•LTU Not Ready. The modem is not in synchronisation with the far end.
•LTU Ready. Modems are synchronised, but control signals are off at both ends of link.
Unit Status
Alarms
Line Quality
Interface Status
Note that other interface specific
messages may appear in the
alarms section
Menu Locked/
Unlocked

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6.6 TEST MENU
This menu allows the user to set test loops and data tests to analyse the performance of the
data link.
Local Loop
On/Off
Loopback
On/Off
Remote Loop
On/Off
V54 Loop
On/Off
Data Test
On/Off
In Service Test
Lamp Test
Self Test
Select Pair
Number of
Errors Received
Patten Type
Time
Select Pair
Local CRC Errors
Far end CRC
Errors
Time
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6.5.5 Menu Locked/Unlocked
To prevent unauthorised tampering with the modem configuration the front panel controls
can be disabled. This MENU item shows the status of this feature.
It’s also possible to change the setting from this menu item by using a special key sequence.
While the Menu locked/unlocked status is showing, you can access the control by pressing
SELECT and SCROLL DOWN at the same time, and while they are pressed you can scroll
through the options with the MENU LEFT button.
Use the PROGRAM button to set. The settings available are:
•Menu Unlocked. All menu items are available.
•Menu Locked. Present settings can be viewed but not changed.
•Menu Limited. As for menu locked but all test menu options are available.

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6.6.3 Remote Loop On/Off
This causes the modem to apply a loop at the far end modem such that data is looped back
to the local end. If a remote loop is on then local loop and loopback are unavailable (If the
local loop or loopback is on, then the remote loop is unavailable).
This loop can also be applied from the customer interface:
For X21:
The DTE should send the ART pattern (11001100) and have its control line “C”set OFF.
For V.35, V.36 and RS530:
Circuit 140 ON - Remote loop ON
Circuit 140 OFF - Remote loop OFF
Circuit 142 indicates that a test loop has been applied.
Circuit 108 (where available) should also be on for this test.
6.6.4 V.54 Loop On/Off
This loop is effectively a remote loop, but used in a configuration where the master to slave
pair of modems form part of a larger network.
The loop request command is sent from the slave modem via the data channel (as a V.54
pattern). This request is then ignored by master modems and passed through the network
until it reaches the ultimate slave unit. This responds to the command and applies the loop.
Note: any rack modems in the data path will also pass through the loop request.
Slave
modem Master modem Master modem Slave modem
Loop request here Loop applied here
Network
Interface Interface
loop requested from this modemloop applied at this modem
(same as loopback applied here)
Transmission
Sys
tem
Transmission
Sys
tem
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6.6.1 Local Loop On/Off
Turning on the local loop causes the modem to loop data back to the customer interface
(loop 3c –ITU X.150). If local loop is on then remote loop and data test are unavailable.
This loop can also be applied from the customer interface:
For X.21:
The DTE should send the ALT pattern (1111000) and have its control line “C”set OFF.
For V.35, V.36 and RS530:
Circuit 141 ON - Local loop ON
Circuit 141 OFF - Local loop OFF
Circuit 142 indicates that a test loop has been applied.
Circuit 108 (where available) should also be on for this test.
6.6.2 Loopback On/Off
This causes the modem to loop data back to the remote end of the link (loop 2b –ITU X.150).
If loopback is on then remote loop and data test are unavailable.
Interface Interface
loop applied here
data returned to remote modem
Transmission
Sys
tem
Transmission
Sys
tem
Interface
Transmission
Sys
tem
Interface
loop applied here
data returned to user interface
Transmission
Sys
tem