Codan 3012 User manual

H F R A D I O C O M M U N I C A T I O N S
REFERENCE MANUAL
HF Data Modem
3012

No part of this manual may be reproduced, transcribed, translated into any language or
transmitted in any form whatsoever without the prior written consent of Codan Limited.
NGT®is a registered trademark of Codan Limited
CALM®is a registered trademark of Codan Limited
Windows®is a registered trademark of Microsoft Corporation
Copyright 2001 Codan Limited
Codan part number 15-04104-EN Issue 2, November 2001

HF Data Modem 3012 Reference Manual i
CODAN
Table of contents
1 About this manual
Standards and icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Acronyms and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
Circuit reference designations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Unit multipliers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
About this issue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-8
Associated documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
2 Overview
High Frequency Data Modem 3012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Channel selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Types of data transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Transmission protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3
Physical description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
3Installation
Unpacking the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Additional equipment required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Terminal connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Transceiver connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5
Cables for connecting transceivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Installing the data modem system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7
Setting up the PC or terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-9
Using a PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Using a terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-9
Setting the station address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Confirming the station address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-10
Checking the operation of the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Checking the connection between the transceiver system and the data modem . . . . . . . . . . . 3-11
Testing the data link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-12

Table of contents
ii HF Data Modem 3012 Reference Manual
4 Operating the data modem
Powering up the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Indicators on the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Modes of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Controlling the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Controlling the data modem using AT commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Switching to local command mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Returning to on-line mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Setting the unit address for polling stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Setting how calls are answered automatically . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
Answering calls manually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Terminating a link (hanging up) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Making selective call transmissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
Making broadcast call transmissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
Making group call transmissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
Enabling/disabling local data echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Enabling/disabling remote data echo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Displaying remote station address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Storing station addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
Dialling stored station addresses (quick dial) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
Setting telephone compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
Changing the state of the DTR input line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
Displaying diagnostic information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14
Changing the response format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15
Saving data modem settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16
Resetting the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16
Resetting to factory defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16
Enabling/disabling data compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
Controlling data flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
Setting the modulation method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18
Displaying data modem product and version number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18
5 Setting up an NGT to operate with the data modem
Installing the data modem with an NGT transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Mounting the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Connecting the data modem to the NGT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Setting up the NGT to operate with the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Setting up the serial port of the NGT using the handset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Setting up the serial port of the NGT using the system programmer . . . . . . . . . . . . . . . . . . . . 5-3
Setting up an NGT network to operate with the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Setting up automatic channel selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

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HF Data Modem 3012 Reference Manual iii
6 Specifications
General specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2
System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-3
Environmental specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-3
Physical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
7 How the data modem works
Technical description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
How the DSP Modem PCB works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-3
Digital signal processor and CoDec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-3
Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
Logic and interfacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-3
Throughput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-4
How the User Connector PCB works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-5
Transceiver interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
Serial ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
8 Maintenance and fault finding
Adjustments and routine maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-2
PCBs and units available as replacements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-2
PCB removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-3
Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
Fault finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
If technical assistance is required... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
Basic fault finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-5
Advanced fault finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6
What you need . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-6
Dismantling the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-6
Fault finding the power supply in the data modem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
Testing the HF subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9
9Drawings
Appendix A—AT commands
Summary of AT commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Summary of AT commands to display S-registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6
Index

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iv HF Data Modem 3012 Reference Manual
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HF Data Modem 3012 Reference Manual v
CODAN
List of figures
Figure 3-1: Rear panel of HF Data Modem 3012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Figure 3-2: Example installation setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Figure 3-3: Connection diagram for the transceiver system and data modem . . . . . . . . . . . . . 3-11
Figure 8-1: Exploded view of HF Data Modem 3012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-6

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vi HF Data Modem 3012 Reference Manual
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HF Data Modem 3012 Reference Manual vii
CODAN
List of tables
Table 3-1: Pinouts for the Terminal connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Table 3-2: Pinouts for the Transceiver connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
Table 3-3: Cables used for Codan transceivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Table 4-1: Operational status as indicated by the LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
Table 4-2: Response codes for the HF Data Modem 3012 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15
Table 5-1: Settings for ALE/CALM, Codan Selcall and Voice Only networks operating with an
HF Data Modem 3012 5-4
Table 8-1: Replacement PCBs and units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-2
Table 8-2: Customer service contact numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-4
Table 8-3: Basic fault finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5
Table A-1: AT commands for the HF Data Modem 3012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Table A-2: AT commands for the HF Data Modem 3012 S-registers . . . . . . . . . . . . . . . . . . . A-6

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HF Data Modem 3012 Reference Manual 1-1
CODAN
1 About this manual
This reference manual is for installation technicians and operators of the High Frequency
Data Modem 3012.
The manual has nine chapters and one appendix:
Chapter 1 About this manual—lists all terms, abbreviations and units used in this
manual
Chapter 2 Overview—contains a general description of the data modem
Chapter 3 Installation—describes how to install the data modem
Chapter 4 Operating the data modem—describes how to operate the data modem
Chapter 5 Setting up an NGT to operate with the data modem—provides specific
information for operating the data modem with a Codan NGT transceiver
Chapter 6 Specifications—contains the specifications for the data modem
Chapter 7 How the data modem works—provides a brief technical description of how
the data modem works
Chapter 8 Maintenance and fault finding—describes how to maintain the data
modem, and the possible causes of faults
Chapter 9 Drawings—contains the drawings referred to in this manual
Appendix A AT commands—lists all the AT commands that may be used with the data
modem
There is an index at the end of this manual.

About this manual
1-2 HF Data Modem 3012 Reference Manual
Standards and icons
The following standards and icons are used in this manual:
This typeface Means...
BOLD/Bold a button, switch or connector
Bold a command that you enter or keyboard key that you press
Courier a segment of text that is taken directly from a computer screen
Italics a cross-reference or text requiring emphasis
This icon Means...
a warning—your actions may cause harm to yourself or the equipment
a caution—proceed with caution as your actions may lead to loss of
data, privacy or signal quality
a note—the text provided next to this icon may be of interest to you
1a step to follow

About this manual
HF Data Modem 3012 Reference Manual 1-3
Definitions
Acronyms and abbreviations
Acronym Means…
ACE asynchronous communications element
ALC automatic level control
ALE automatic link establishment
ARQ automatic repeat request
ASCII American standard code for information interchange
AT attention
CALM Codan automated link management
CD carrier detect
CICS computer interface command set
CoDec coder/decoder
CPU central processing unit
CTS clear to send
DC direct current
DSP digital signal processor
DSR data set ready
DTE data terminal equipment
DTR data terminal ready
EEPROM electrically erasable programmable read only memory
EPROM erasable programmable read only memory
ESR equivalent series resistance
FIFO first-in first-out
GND ground
HF high frequency
IC integrated circuit
I2C inter integrated circuit
I/O input/output
LED light emitting diode
NC not connected

About this manual
1-4 HF Data Modem 3012 Reference Manual
NSP NGT System Programmer
OC open collector (active low)
PC personal computer
PCB printed circuit board
PLCC plastic J-leaded chip carrier
p−p peak to peak
PTT press to talk
QPSK quadrature phase shift keying
RAM random access memory
RTS request to send
RxD receive data
SRAM static random access memory
SSB single sideband
TSOP thin small outline package
TTL transistor−transistor logic
TxD transmit data
Acronym Means…

About this manual
HF Data Modem 3012 Reference Manual 1-5
Glossary
Term Description
ACE A peripheral semiconductor device used to provide additional serial
interfaces to a microcontroller or digital signal processor.
AT commands Set of commands commonly used to operate many types of modems.
CHIRP A robust signalling protocol used by the data modem during link
establishment.
coder/decoder A device combining analog to digital and digital to analog converters.
data terminal
equipment An RS232-related term indicating a personal computer or terminal.
digital signal
processor A microprocessor-like device that is designed to quickly process high volume digital data streams.
effective
throughput Average data transfer rate taking the effects of data compression into account. For example, if system throughput is 1000 bps and data
compression reduces data size by 50%, the effective throughput is
2000 bps.
first-in first-out A buffer used in serial communications devices to reduce CPU
overheads.
frequency offset Difference between the frequencies being used by a sending and a
receiving modem station. The variation is due to changes in
temperature, variations in power supply voltage or the aging of
components.
signalling rate Rate at which data is transmitted (this remains constant at 2400 bps).
throughput Average data transfer rate between stations (this varies with different
channel conditions).
transceiver The unit that converts audio signals to radio frequencies that may be
transmitted on air, and that converts the radio frequencies it receives
into audio signals. In this manual, when referring to the NGT,
transceiver equates to the RF unit.
transmission
protocol Method used by a modem to transmit and receive information.

About this manual
1-6 HF Data Modem 3012 Reference Manual
Circuit reference designations
Units
Abbreviation Designation
C capacitor
D diode—small signal and power
IC integrated circuit, thick film hybrid etc
L inductor
S switch
TP test point
V semiconductor (not including small signal and power diodes)
Measurement Unit Abbreviation
Current ampere A
Distance metre m
Frequency hertz Hz
Impedance ohm Ω
Mass gram g
Power watt W
Rate of data transfer baud baud
Rate of data transfer bits per second bps
Temperature degrees Celsius °C
Temperature (Absolute) kelvin K
Time hour hr
Time second s
Voltage volt V

About this manual
HF Data Modem 3012 Reference Manual 1-7
Unit multipliers
Unit Name Multiplier
nnano10
–9
µ micro 10–6
m milli 10–3
ddeci10
–1
k kilo 103
Mmega10
6
Ggiga10
9

About this manual
1-8 HF Data Modem 3012 Reference Manual
About this issue
This is the second issue of the HF Data Modem 3012 Reference Manual.
Associated documents
Other publications associated with the HF Data Modem 3012 are:
•9102 Fax and Data Controller Software User Guide (Codan part number 15-04039)
•NGT System Programmer User Guide (Codan part number 15-04105-EN)
•NGTAR Transceiver User Guide (Codan part number 15-04118-EN)
•NGT SR Transceiver User Guide (Codan part number 15-04096-EN)
•NGTAR, SR and VR Transceiver Reference Manual (Codan part number
15-04099-EN)

HF Data Modem 3012 Reference Manual 2-1
CODAN
2 Overview
This chapter describes the features of the HF Data Modem 3012. It includes:3434
•a brief functional description of the data modem (2-2)
•a brief physical description of the data modem (2-5)

Overview
2-2 HF Data Modem 3012 Reference Manual
High Frequency Data Modem 3012
Introduction
The HF Data Modem 3012, when combined with the appropriate HF SSB transceiver
and computer terminal, provides error-free transmission and reception of data on an HF
channel. It is particularly useful for long-range communications in remote areas where
existing communications are poor or non-existent.
The data modem operates at 12 V DC in fixed base and mobile installations. It
incorporates data compression to boost effective throughput and is easily integrated with
Codan voice and signalling networks.
A typical HF Data Modem 3012 station comprises:
•HF Data Modem 3012
•Codan ‘data-capable’transceiver
•power supply
•computer terminal with appropriate communications software
•antenna system
The data modem is supplied with Codan 9102 Fax and Data Controller Software. This
software provides easy operation of the data modem for simple messaging, chat and file
transfer between data stations. Alternatively, the data modem may be controlled using
standard AT commands from a terminal. Virtually any software that operates on standard
telephone modems will operate over HF via the AT commands.
The data modem is able to send email over HF with other third party email software.
Channel selection
HF channels may be manually selected using the transceiver or the data modem.
If a data call is sent while the NGT transceiver is scanning a CALM network, the
transceiver automatically selects the channel using the CALM network.
Types of data transmission
There are three types of data transmission:
•selective call
•group call
•broadcast call
Selective calls guarantee error-free transmission, while group and broadcast calls may be
subject to errors under poor channel conditions.