Mocomtech Cdm Qx Users Manual Satellite Modem

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CDM-Qx
Multi-Channel Satellite Modem with DoubleTalk™
Carrier-in-Carrier® Installation and Operation Manual
Note: This manual incorporates data for the CDM-Qx and CDM-QxL.
IMPORTANT NOTE: The information contained in this document supersedes all previously published
information regarding this product. Product specifications are subject to change without prior notice.

Part Number MN/CDMQX.IOM

Revision 5

Errata A
Comtech EF Data Documentation Update
Subject:

Revised Acquisition Range for Demodulator

Date:
Document:

January 23, 2007
CDM-Qx, Multi-Channel Satellite Modem, Installation and
Operation Manual, Revision 5, dated January 20, 2007
MN/CDMQx.EA5
Attach this page to page A-3

Part Number:
Collating Instructions:

Comments:
The following changes affects the acquisition rate specified in Section A.2.

Change Specifics:
Acquisition range

±1 to ±32 kHz, Symbol rate > 64 ksps (70/140 MHz)
±1 to ± (Symbol rate/2) kHz , Symbol Rate <=64 ksps (70/140 MHz)
±1 to ±200 kHz, Symbol rate > 625 ksps (L-Band)
±1 to ± 32 kHz, 64 ksps < Symobol Rate <=625 ksps (L-Band)
±1 to ± (Symbol rate/2)kHz, Synbol Rate <=64ksps (L-Band)
Programmable in 1 kHz increments.

s:\tpubs\manuals\released_word\modems\cdmqx_rev5\text\errata a.doc

Errata B
Comtech EF Data Documentation Update
Subject:

Delete COMBINED TRANSMIT POWER Menu

Date:
Document:

January 23, 2007
CDM-Qx, Multi-Channel Satellite Modem, Installation and
Operation Manual, Revision 5, dated January 20, 2007
MN/CDMQx.EB5
Attach this page to page 5-22

Part Number:
Collating Instructions:

Comments:
Delete Combined Transmit Power menu.

s:\tpubs\manuals\released_word\modems\cdmqx_rev5\text\errata b.doc

Errata C
Comtech EF Data Documentation Update
Subject:

Revise Sub-Menu for Vit+RS and TCM+RS

Date:
Document:

January 23, 2007
CDM-Qx, Multi-Channel Satellite Modem, Installation and
Operation Manual, Revision 5, dated January 20, 2007
MN/CDMQx.EC5
Attach this page to page 5-25

Part Number:
Collating Instructions:

Comments:
Revised Sub-Menu for Vit+RS and TCM+RS to delete Viterbi and TPC.

If Vit+RS orTCM+RS is selected, the following sub-menu will be displayed:

Rx Rs (n/k):
IESS-310 network

(◄ ►, ENT)
(219/201)

s:\tpubs\manuals\released_word\modems\cdmqx_rev5\text\errata c.doc

Errata D
Comtech EF Data Documentation Update
Subject:

Add Sub-Menu for Vit+RS and TCM+RS

Date:
Document:

January 23, 2007
CDM-Qx, Multi-Channel Satellite Modem, Installation and
Operation Manual, Revision 5, dated January 20, 2007
MN/CDMQx.ED5
Attach this page to page 5-16

Part Number:
Collating Instructions:

Comments:
Added requirements for IESS-310 mode to Tx menu.

If Vit+RS orTCM+RS is selected, the following sub-menu will be displayed:

Tx Rs (n/k):
IESS-310 network

(◄ ►, ENT)
(219/201)

s:\tpubs\manuals\released_word\modems\cdmqx_rev5\text\errata d.doc

CDM-Qx
Multi-Channel Satellite Modem with DoubleTalk™
Carrier-in-Carrier Installation and Operation Manual
Note: This manual incorporates data for the CDM-Qx and CDM-QxL.
Comtech EF Data is an ISO 9001
Registered Company

Part Number MN/CDMQx.IOM
Revision 5
January 20,2007

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

CUSTOMER SUPPORT
Contact the Comtech EF Data Customer Support Department for:
Product support or training
Information on upgrading or returning a product
Reporting comments or suggestions concerning manuals
Contact Customer Support using any of the following methods:
Mail:

Comtech EF Data

Email: service@comtechefdata.com

Customer Support Department
2114 West 7th Street

Internet: www.comtechefdata.com

Tempe, Arizona 85281 USA
Phone: 480.333.2200 (Main Comtech EF Data Number)
480.333.4357 (Customer Support Desk)
Fax:

480.333.2161

To return a Comtech EF Data product (in-warranty and out-of-warranty) for repair or
replacement:
1. Request a Return Material Authorization (RMA) number from the Comtech
EF Data Customer Support Department.
2. Be prepared to supply the Customer Support representative with the model
number, serial number, and a description of the problem.
3. To ensure that the product is not damaged during shipping, pack the product
in its original shipping carton/packaging.
4. Ship the product back to Comtech EF Data. (Shipping charges should be
prepaid.)

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

Table of Contents

CHAPTER 1.
1.1

INTRODUCTION................................................................................ 1–1

Introduction................................................................................................................................1–1

1.2
Features.......................................................................................................................................1–2
1.2.1
DoubleTalk™ Carrier-in-Carrier® .....................................................................................1–3
1.2.2
Software – Flash Upgrading................................................................................................1–3
1.2.3
Verification .........................................................................................................................1–3
1.2.4
Data Interfaces ....................................................................................................................1–4
1.2.5
Turbo Product Coding......................................................................................................... 1–4
1.2.6
Remote Control ...................................................................................................................1–4
1.3

Major Assemblies.......................................................................................................................1–4

1.4
FAST Options and Hardware Options ....................................................................................1–5
1.4.1
FAST Accessible Options ...................................................................................................1–6
1.4.2
FAST System Theory.......................................................................................................... 1–6
1.4.3
Implementation ...................................................................................................................1–6
1.4.4
Hardware Options ...............................................................................................................1–6
1.4.5
Supporting Hardware and Software (Future Feature) .........................................................1–7
1.5

L-Band ........................................................................................................................................1–7

1.6

Compatibility..............................................................................................................................1–7

CHAPTER 2.

INSTALLATION ................................................................................. 2–1

2.1

Unpacking...................................................................................................................................2–1

2.2

Mounting.....................................................................................................................................2–2

2.3

Configuration .............................................................................................................................2–4

2.4

Select Internal IF Loop..............................................................................................................2–4

2.5

Connect External Cables........................................................................................................... 2–4

iii

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

CHAPTER 3.

FUNCTIONAL DESCRIPTION .......................................................... 3–1

CHAPTER 4.

EXTERNAL CONNECTIONS ............................................................ 4–1

4.1

Introduction................................................................................................................................4–1

4.2

Front Panel .................................................................................................................................4–2

4.3

Rear Panel ..................................................................................................................................4–3

4.4
Chassis Connections ..................................................................................................................4–5
4.4.1
USB Port .............................................................................................................................4–5
4.4.2
M&C 10/100BaseT Connector............................................................................................4–5
4.4.3
485/232 Connector ..............................................................................................................4–5
4.4.4
Alarms Connector ...............................................................................................................4–6
4.4.5
Balanced G.703 Connector Tx/Rx Connector.....................................................................4–7
4.4.6
Unbalanced G.703 Tx/Rx Connectors ...............................................................................4–7
4.4.7
RS-530 Data Interface Connector .......................................................................................4–8
4.4.8
RX and TX IF Connectors ..................................................................................................4–9
4.4.9
Ref Connector .....................................................................................................................4–9
4.5

AC Power Connector................................................................................................................. 4–9

4.6

DC Power Connector................................................................................................................. 4–9

4.7

Ground Connector ................................................................................................................... 4–10

CHAPTER 5.
5.1

FRONT PANEL OPERATION ........................................................... 5–1

Introduction ...............................................................................................................................................5–1

5.2
Left-Hand Display Area............................................................................................................................5–4
5.2.1
Modems .............................................................................................................................................5–4
5.2.2
Redundancy .......................................................................................................................................5–5
5.2.3
Spectrum Analyzer ............................................................................................................................5–5
5.3

Right-Hand Display Area .........................................................................................................................5–6

5.4

Accessing the Display Area.......................................................................................................................5–6

5.5

Opening Screen..........................................................................................................................................5–8

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

5.6
TOP LEVEL SELECTION ......................................................................................................5–8
5.6.1
CONFIG..............................................................................................................................5–9
5.6.2
MONITOR ........................................................................................................................ 5–49
5.6.3
TEST: ................................................................................................................................5–56
5.6.4
INFO (Information)........................................................................................................... 5–61
5.6.5
SAVE/LOAD .................................................................................................................... 5–65
5.6.6
UTILITY ...........................................................................................................................5–68

CHAPTER 6.

FORWARD ERROR CORRECTION OPTIONS ................................ 6–1

6.1

Introduction................................................................................................................................6–1

6.2

Viterbi .........................................................................................................................................6–2

6.3

Reed-Solomon Outer Codec......................................................................................................6–3

6.4

Trellis Coding .............................................................................................................................6–5

6.5
Turbo Product Codec (Hardware Option) ..............................................................................6–6
6.5.1
Introduction .........................................................................................................................6–6
6.5.2
The Evolution of TPC in Comtech Products.......................................................................6–6
6.5.3
End-to-End Processing Delay .............................................................................................6–7
6.5.4
Comparison of all TPC Modes............................................................................................6–8

CHAPTER 7.

EDMAC CHANNEL............................................................................ 7–1

7.1

Theory Of Operation .................................................................................................................7–1

7.2

M&C Connection .......................................................................................................................7–2

7.3

Setup Summary..........................................................................................................................7–3

CHAPTER 8.
8.1

AUTOMATIC UPLINK POWER CONTROL ...................................... 8–1

Introduction................................................................................................................................8–1

8.2
Setting AUPC Parameters.........................................................................................................8–2
8.2.1
Target Eb/No.......................................................................................................................8–2
8.2.2
Max Range ..........................................................................................................................8–2
8.2.3
Alarm...................................................................................................................................8–3
8.2.4
Demod Unlock ....................................................................................................................8–3
8.3

Compensation Rate....................................................................................................................8–3

8.4

Monitoring..................................................................................................................................8–4

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

CHAPTER 9.

DOUBLETALK™ CARRIER-IN-CARRIER® OPERATION ............... 9–1

CHAPTER 10.

REDUNDANCY .............................................................................. 10–1

CHAPTER 11.

ETHERNET MANAGEMENT ......................................................... 11–1

11.1

Introduction................................................................................................................. 11–1

11.2

Ethernet Management Interface Protocols .............................................................. 11–1

11.3

Web Server (HTTP) Interface ................................................................................... 11–2

11.4 SNMP Interface........................................................................................................... 11–8
11.4.1
Management Information Base (MIB) Files......................................................... 11–8
11.4.2
SNMP Community Strings ................................................................................... 11–9
11.4.3
SNMP Traps.......................................................................................................... 11–9
11.5

Telnet Interface ......................................................................................................... 11–10

APPENDIX A.

SUMMARY OF SPECIFICATIONS ................................................. A–1

APPENDIX B.

FLASH UPGRADING ...................................................................... B–1

APPENDIX C.

REMOTE CONTROL........................................................................ C-1

APPENDIX D. CARRIER-IN-CARRIER® PERFORMANCE
CHARACTERIZATION ................................................................................... D–1

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

About this Manual
This manual provides installation and operation information for the Comtech EF Data
CDM-Qx Multi-Channel Modem with DoubleTalk™ Carrier-in-Carrier®. This is a
technical document intended for earth station engineers, technicians, and operators
responsible for the operation and maintenance of the CDM-Qx.

CONVENTIONS AND REFERENCES
METRIC CONVERSION
Metric conversion information is located on the inside back cover of this manual. This
information is provided to assist the operator in cross-referencing English to Metric
conversions.

CAUTIONS AND WARNINGS

CAUTION

CAUTION indicates a hazardous situation that, if not avoided, may
result in minor or moderate injury. CAUTION may also be used to
indicate other unsafe practices or risks of property damage.

WARNING

WARNING indicates a potentially hazardous situation
that, if not avoided, could result in death or serious
injury.

Indicates information critical for proper equipment
function.
IMPORTANT

REPORTING COMMENTS OR SUGGESTIONS CONCERNING THIS MANUAL
Comments and suggestions regarding the content and design of this manual will be
appreciated. To submit comments, please contact the Comtech EF Data Technical
Publications Department: techpub@comtechefdata.com

vii

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

ELECTRICAL SAFETY
The CDM-Qx Multi-Channel Modem with DoubleTalk™ Carrier-in-Carrier® has been
shown to comply with the following safety standard:
•

EN 60950: Safety of Information Technology Equipment, including electrical
business machines

The equipment is rated for operation over the range 100 to 240 VAC. It has a maximum
power consumption of 60 watts, and draws a maximum of 600 mA.

IMPORTANT

The user should observe the following instructions:

FUSES
The CDM-Qx is fitted with two fuses - one each for line and neutral connections. These
are contained within the body of the IEC power inlet connector, behind a small plastic
flap.
•

For 115 and 230 VAC operation, use T1.25A, 20mm fuses.

FOR CONTINUED OPERATOR SAFETY, ALWAYS REPLACE THE FUSES WITH
THE CORRECT TYPE AND RATING.

ENVIRONMENTAL
The CDM-Qx must not be operated in an environment where the unit is exposed to
extremes of temperature outside the ambient range 0 to 50°C (32° to 122°F),
precipitation, condensation, or humid atmospheres above 95% RH, altitudes (unpressurized) greater than 2000 meters, excessive dust or vibration, flammable gases,
corrosive or explosive atmospheres.
Operation in vehicles or other transportable installations that are equipped to provide a
stable environment is permitted. If such vehicles do not provide a stable environment,
safety of the equipment to EN60950 may not be guaranteed.

viii

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

INSTALLATION
The installation and connection to the line supply must be made in compliance to local or
national wiring codes and regulations.
The CDM-Qx is designed for connection to a power system that has separate ground, line
and neutral conductors. The equipment is not designed for connection to power system
that has no direct connection to ground.
The CDM-Qx is shipped with a line inlet cable suitable for use in the country of
operation. If it is necessary to replace this cable, ensure the replacement has an equivalent
specification. Examples of acceptable ratings for the cable include HAR, BASEC and
HOXXX-X. Examples of acceptable connector ratings include VDE, NF-USE, UL, CSA,
OVE, CEBEC, NEMKO, DEMKO, BS1636A, BSI, SETI, IMQ, KEMA-KEUR and
SEV.
The modulator and demodulator cards shall not be plugged-in when the
modem is powered on. Damage to the cards can be the result.
CAUTION

International Symbols:
Symbol

Definition

Symbol

Alternating Current

Protective Earth

Fuse

Chassis Ground

Definition

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

TELECOMMUNICATIONS TERMINAL EQUIPMENT DIRECTIVE
In accordance with the Telecommunications Terminal Equipment Directive 91/263/EEC,
this equipment should not be directly connected to the Public Telecommunications
Network.

CE MARK
Comtech EF Data declares that the CDM-Qx meets the necessary requirements for the
CE Mark.

TRADEMARKS
Carrier-in Carrier is a registered trademark of Comtech EF Data Corporation.
DoubleTalk is a trademark of Applied Signal Technology, Inc.

CDM-Qx Satellite Modem
Preface

Revision 5
MN/CDMQx.IOM

WARRANTY POLICY
This Comtech EF Data product is warranted against defects in material and workmanship
for a period of two years from the date of shipment. During the warranty period, Comtech
EF Data will, at its option, repair or replace products that prove to be defective.
For equipment under warranty, the customer is responsible for freight to Comtech EF
Data and all related custom, taxes, tariffs, insurance, etc. Comtech EF Data is responsible
for the freight charges only for return of the equipment from the factory to the customer.
Comtech EF Data will return the equipment by the same method (i.e., Air, Express,
Surface) as the equipment was sent to Comtech EF Data.

LIMITATIONS OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper installation or
maintenance, abuse, unauthorized modification, or operation outside of environmental
specifications for the product, or, for damages that occur due to improper repackaging of
equipment for return to Comtech EF Data.
No other warranty is expressed or implied. Comtech EF Data specifically disclaims the
implied warranties of merchantability and fitness for particular purpose.

EXCLUSIVE REMEDIES
The remedies provided herein are the buyer's sole and exclusive remedies. Comtech EF
Data shall not be liable for any direct, indirect, special, incidental, or consequential
damages, whether based on contract, tort, or any other legal theory.

DISCLAIMER
Comtech EF Data has reviewed this manual thoroughly in order that it will be an easy-touse guide to your equipment. All statements, technical information, and
recommendations in this manual and in any guides or related documents are believed
reliable, but the accuracy and completeness thereof are not guaranteed or warranted, and
they are not intended to be, nor should they be understood to be, representations or
warranties concerning the products described. Further, Comtech EF Data reserves the
right to make changes in the specifications of the products described in this manual at any
time without notice and without obligation to notify any person of such changes.
If you have any questions regarding the equipment or the information in this manual,
contact the Comtech EF Data Customer Support Department.
xi

CDM-Qx Satellite Modem
Preface

Revision 5
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Notes:

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xii

Chapter 1. INTRODUCTION

1.1

Introduction
The CDM-Qx, Multi-Channel Satellite Modem with DoubleTalk™ Carrier-in-Carrier® is
a 70/140 MHz (or CDM-QxL with 950MHz-1950MHz L Band operation) modular multichannel modem with redundancy contained in a single rack unit (1RU) chassis. The
Modem offers flexibility, redundancy, integration, and performance with four slots
configurable as modulators or demodulators.
The CDM-Qx/QxL supports DoubleTalk Carrier-in-Carrier® option, allowing transmit
(Tx) and receive (Rx) carriers in a full-duplex link to use the same transponder segment.

Figure 1-1. CDM-Qx/QxL

1–1

CDM-Qx Satellite Modem
Introduction

1.2

Revision 5
MN/CDMQx.IOM

Features
The Modem includes such features as the following:
•
•
•
•
•
•
•

•
•
•
•

•
•
•
•
•
•
•
•
•
•

DoubleTalk™ Carrier-in-Carrier® allowing Tx and Rx carriers of a full-duplex
link to use the same transponder segment
CDM-Qx: 50 to 90 and 100 to 180 MHz frequency range
CDM-QxL: 950 MHz-1950 MHz L-band
32 kbps to 20 Mbps
BPSK, QPSK, 8-PSK, 16-QAM operation
Flexible Configuration:
• 1 modem or 2 modems configured as 1:1
• Up to 4 demodulators
Optional Built In Redundancy:
• 1:1 modem
• Up to 1:3 modulator
• Up to 1:3 demodulator
EIA-422/-530, V.35, G.703 (E1/T1) and HSSI Interfaces
1 to 4 Ports of G.703 (E1 with D&I ) Quad E1 Interface Card
10/100 BaseT Ethernet, RS-232 or RS-485 for M&C remote control
Forward Error Correction (FEC) choices included:
• Viterbi
• Viterbi with Reed-Solomon
• Trellis and Reed-Solomon
• Optional, 2nd Generation Turbo Product Coding (TPC)
(IESS-315 compliant)
Fully Accessible System Topology (FAST)
Asymmetric Loop Timing
Common frequency reference for all modules
Optional High Stability Reference
Optional Redundant Power Supply
Individual or summed Modulator output power control
Interoperable with: CDM-550T, -570L, -600, -600L, SDM-300A, -300L3, and
-8000 modems (in compatible modes)
Drop and Insert, closed network version
FSK, for communicating to Comtech EF Data transceivers
EDMAC, Automatic Uplink Power Control

1–2

CDM-Qx Satellite Modem
Introduction

1.2.1

Revision 5
MN/CDMQx.IOM

DoubleTalk™ Carrier-in-Carrier®
Designed for bandwidth compression, Carrier-in-Carrier is based on Applied Signal
Technology’s DoubleTalk which uses “Adaptive Cancellation,” a patented (Unites States
Patent # 6,859,641) technology that allows full duplex satellite links to transmit
concurrently in the same segment of transponder bandwidth. Available as an option to
the modem, this added dimension can result in a significant improvement in satellite
transponder utilization.

1.2.2

Software – Flash Upgrading
The internal software is both powerful and flexible, permitting storage and retrieval of up
to 10 different modem configurations. The modem uses ‘flash memory’ technology
internally, and new firmware can be uploaded to the unit from an external PC. This
simplifies software upgrading, and updates can now be sent via the Internet, e-mail, or on
disk. The upgrade can be performed without opening the unit by simply connecting the
modem to the USB port or Ethernet port of a computer.

1.2.3

Verification
The Modem includes many test modes and loopbacks for rapid verification of the correct
functioning of the unit. Of particular interest is the IF loopback, which permits the user to
perform a quick diagnostic test without having to disturb external cabling. During
loopback, all of the receive configuration parameters on the selected Demodulator are
temporarily changed to match those of the selected Modulator, and an internal RF switch
connects the modulator output to the demodulator input. When normal operation is again
selected, all of the previous values are restored.

1–3

CDM-Qx Satellite Modem
Introduction

1.2.4

Revision 5
MN/CDMQx.IOM

Data Interfaces
The Modem can be ordered with a number of interfaces. Each data interface can operate
on a Modulator or Demodulator. This allows the user to exchange interface cards for
different applications. The interfaces offered include:
•
•
•
•
•

1.2.5

EIA/TIA-530
• (EIA-422) DCE (at rates up to 12 Mbps)
• V.35 DCE (at rates up to 12 Mbps)
G.703 Balanced T1 & E1 (DB-15) with D&I
G.703 Unbalanced T1 & E1 (BNC)
EIA/TIA-612/613 HSSI (50-pin SCSI connector, to 20 Mbps)
1 to 4 Ports of G.703 (E1 with D&I ) Quad E1 Interface Card, (DB-9F)

Turbo Product Coding
The Modem offers optional 2nd generation Turbo Product Codec (TPC). TPC
simultaneously offers increased coding gain, lower decoding delay, and significant
bandwidth savings. The TPC provides:
•
•
•
•

1.2.6

BPSK 5/16 and 21/44
QPSK 21/44, 3/4, 7/8 and 17/18
8-PSK 3/4, 7/8, and 17/18
16-QAM 3/4 and 7/8

Remote Control
The operator may configure and monitor the modem from the front panel, or through the
remote M&C port. M&C is via RS-232, RS-485 (2/4 wire) or 10/100 BaseT Ethernet.

1–4

CDM-Qx Satellite Modem
Introduction

1.3

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MN/CDMQx.IOM

Major Assemblies
Assembly
PL/10570-1
PL/10570-2
PL/10070-1
PL/10069
PL/10073
PL/11128
PL/10635
PL/10071
PL/10072
AS/11014
PL/10678
PL/10697
PL/10698
PL/12608-1
PL/10898-1
PL/10416-1
PL/10416-2
PL/12798-1
PL/12798-2

Description
1 PPM Reference IF Backplane 70/140 MHz IF
0.1 PPM Reference IF Backplane 70/140 MHz IF
0.1 PPM Reference IF Backplane L-Band IF
Digital Backplane
Monitor and Control Card
70/140 MHz IF Modulator
70/140 MHz IF Demodulator with Carrier in Carrier
L-Band IF Modulator
L-Band IF Demodulator with Carrier in Carrier®
Turbo Codec – Simplex
EIA-530 Duplex Data interface
G.703 Balanced Duplex Data Interface
G.703 Unbalanced Duplex Data Interface
Quad E1 G.703 Data Interface Module
EIA-612/613 HSSI Interface
AC Chassis, 70/140 IF
DC Chassis, 70/140 IF
AC Chassis, L-Band
DC Chassis, L-Band

1–5

CDM-Qx Satellite Modem
Introduction

1.4

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FAST Options and Hardware Options
The Modem is extremely flexible and powerful, and incorporates a large number of
optional features. Some customers may not require all of these features, and therefore, in
order to permit a lower initial cost, the Modem may be purchased with only the desired
modules and features enabled. If, at a later date, a customer wishes to upgrade the
functionality of a modulator or demodulator, Comtech EF Data provides a system known
as FAST (Fully Accessible System Topology) which permits the purchase and
installation of options through the use of special authorization codes, entered through the
front panel, or remotely.
The base configuration of the modulators and demodulators are equipped with Viterbi
and R-S codecs. It offers modulation types, and data rates up to 5 Mbps. It is, however,
limited to Closed Network operation.
The following table shows what other options are available:
Modulator & Demodulator
Options

Description and Comments

Low Rate Variable
Mid-Rate Variable
Full Rate Variable
8-PSK
16-QAM
DoubleTalk Carrier-in-Carrier
DoubleTalk Carrier-in-Carrier
DoubleTalk Carrier-in-Carrier
DoubleTalk Carrier-in-Carrier
DoubleTalk Carrier-in-Carrier

Data rate 32 kbps to 5 Mbps
Data rate 32 kbps to 10.0 Mbps
Data rate 32 kbps to 20.0 Mbps
Modulation Type
Modulation Type
128 ksps – 512 kbps
128 ksps – 1 Mbps
128 ksps – 2.5 Mbps
128 ksps – 5 Mbps
128 ksps – 1.0 Mbps

DoubleTalk Carrier-in-Carrier
Redundancy Capability
Turbo Codec – high rate
High Stability Reference
Low Stability Reference
75Ω TX/RX Impedance
50Ω TX/RX Impedance

128 ksps – 20 Mbps
1:1 or 1:2 or 1:3 Redundancy
20 Mbps Turbo Codec
Internal 10 MHz reference – 0.1 x 10-6
Internal 10 MHz reference – 1 x 10-6
75Ω impedance with BNC female connectors
50Ω impedance with N female connectors (LBand)

*Factory installed only.

1–6

Option
Installation
Method
Base Unit
FAST
FAST
FAST
FAST
FAST
FAST
FAST
FAST
FAST
FAST
FAST
Hardware
Hardware*
Hardware*
Hardware*
Hardware*

CDM-Qx Satellite Modem
Introduction

1.4.1

Revision 5
MN/CDMQx.IOM

FAST Accessible Options
Comtech EF Data’s FAST system allows immediate implementation of different options
through the user interface keypad. All FAST options are available through the basic
platform unit.

1.4.2

FAST System Theory
FAST is an enhancement feature available in Comtech EF Data products, enabling onlocation upgrade of the operating feature set - in the rack - without removing a modem
from the setup. When service requirements change, the operator can upgrade the topology
of the modem to meet those requirements within minutes after confirmation by Comtech
EF Data. This accelerated upgrade can be accomplished only because of FAST’s
extensive use of programmable devices incorporating Comtech EF Data-proprietary
signal processing techniques. These techniques allow the use of a unique access code to
enable configuration of the available hardware. The access code can be purchased at any
time from Comtech EF Data. Once obtained, the access code is loaded into the unit
through the front panel keyboard or the rear remote port.
With the exclusive FAST technology, operators have maximum flexibility for enabling
functions as they are required. FAST allows an operator to order a modem precisely
tailored for the initial application.

1.4.3

Implementation
FAST is factory-implemented in the modem at the time of order. Hardware options for
basic modems can be ordered and installed either at the factory or in the field. The
operator can select options that can be activated easily in the field, depending on the
current hardware configuration of the product. The Activation Procedure is described in
Appendix C.

1.4.4

Hardware Options
There are four hardware options available.
There is the Comtech EF Data Turbo Product Codec (TPC), representing a very
significant development in the area of FEC. It consists of a plug-in daughter card
(SIMM module) that is field upgradeable. The TPC option provides data rate capability
up to 20 Mbps, and code rates of:
•
•
•
•
•

Rate 5/16 (BPSK)
Rate 21/44 (BPSK, QPSK)
Rate 3/4 (QPSK, 8-PSK, and 16-QAM)
Rate 7/8 (QPSK, 8-PSK, and 16-QAM)
Rate 17/18 (QPSK, 8-PSK)
1–7

CDM-Qx Satellite Modem
Introduction

Revision 5
MN/CDMQx.IOM

Turbo Product Coding provides one of the best Forward Error Correction technologies
currently available, and is now offered with a sufficient range of code rates and
modulation types to optimize link performance under any conditions.
The second hardware option is the Internal Reference Stability. The high stability option
includes a 1 x 10-7 10 MHz reference oscillator on the IF Backplane board, while the low
stability option has a 1 x 10-6 10 MHz reference on the IF Backplane board. This option
must be configured in the factory at the time of order.
The third hardware option is the IF Impedance and Connectors. The IF may be
configured with either BNC female connectors at 75Ω impedance, BNC female
connectors at 50Ω impedance, or TNC female connectors at 50Ω impedance. This option
also must be configured in the factory at the time of order.
The fourth hardware option is the Quad E1 Data Interface Module. This gives the user
1 to 4 ports of E1, (each are D&I capable). These ports must use a synchronous E1
reference. This option also must be configured in the factory at the time of order.

1.4.5

Supporting Hardware and Software
The Modem incorporates an FSK serial link that can be activated on the RX-IF port for
purpose of communicating with an FSK capable Transceiver. In this manner, a user may
monitor, configure, and control the transceiver using the front panel display and keypad
of the modem or the modem’s remote control interface. The EDMAC channel can be
used to convey M&C interface to a transceiver at the distant end of a satellite link if it is
connected to a modem.

1–8

CDM-Qx Satellite Modem
Introduction

1.5

Revision 5
MN/CDMQx.IOM

L-Band
Fully configured, the modem will meet or exceed all of the applicable requirements in
IESS-315 and is available with a full range of industry standard digital interfaces. The
modem expands the capabilities into L-Band frequencies. Utilizing advanced technology
and proprietary digital signal processing techniques, the design eliminates analog
circuitry to perform modem signal processing, resulting in higher reliability and reduced
packaging size.

1.6

Compatibility
The Modem is backwards compatible with a number of Comtech EF Data CDM modems,
SDM modems, and SLM modems.

1–9

CDM-Qx Satellite Modem
Introduction

Revision 5
MN/CDMQx.IOM

Notes:

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1–10

Chapter 2. INSTALLATION

2.1

Unpacking
Inspect shipping containers for damage. If shipping containers are damaged, keep them
until the contents of the shipment have been carefully inspected and checked for normal
operation.
The modem and manual are packaged in pre-formed, reusable, cardboard cartons
containing foam spacing for maximum shipping protection.
Do not use any cutting tool that will extend more than 1 inch into the
container. This can cause damage to the modem.
CAUTION

Unpack the modem as follows:
1. Cut the tape at the top of the carton indicated by OPEN THIS END.
2.

Remove the cardboard/foam space covering the modem.

Remove the modem, manual, and power cord from the carton.

Save the packing material for storage or reshipment purposes.

Inspect the equipment for any possible damage incurred during shipment.

Check the equipment against the packing list to ensure the shipment is correct.

Refer to the following sections for further installation instructions.

2–1

CDM-Qx Satellite Modem
Installation

2.2

Revision 5
MN/CDMQx.IOM

Mounting
If the modem is to be mounted in a rack, ensure that there is adequate clearance for
ventilation, particularly at the sides. In rack systems where there is high heat dissipation,
forced air-cooling must be provided by top or bottom mounted fans or blowers. Under no
circumstance should the highest internal rack temperature be allowed to exceed 50°C
(122°F).

2.2.1

Optional Rear-Mounting Installation Bracket
Install optional installation brackets (Figure 2-1) using mounting kit KT/6228-2:
Mounting Kit KT/6228-2 (Optional)
Quantity
2
4
2
2
2
4

Part Number

Description

HW/10-32SHLDR
HW/10-32FLT
HW/10-32SPLIT
HW/10-32HEXNUT
FP/6138-1
HW/10-32x1/2RK

Screw, #10 Shoulder
Washer, #10 Flat
Washer, #10 Split
Nut, #10 Hex
Bracket, Rear Support
Bolt, #10 Rack Bracket

The tools required for this installation are a medium Phillips™ screwdriver and a 5/32-inch
SAE Allen™ Wrench.
The CDM-QD is assembled into the equipment rack as shown in Figure 2-1:
Step

Procedure

Secure the #10 shoulder screws to the unit chassis through the rear
right and left side mounting slots, using the #10 flat washers, #10
split washers, and #10 hex nuts as shown.

Install the rear support brackets onto the equipment rack threaded
rear mounting rails, using the #10 bracket bolts.

Mount the unit into the equipment rack, ensuring that the shoulders
of the #10 shoulder screws properly engage into the rear support
bracket slots.

2–2

CDM-Qx Satellite Modem
Installation

Revision 5
MN/CDMQx.IOM

Equipment Rack
Rear Mounting Rail

#10 Shoulder Screw

Support Bracket

#10 Flat Washer
#10 Flat Washer
#10 Bracket Bolt

#10 Split Washer
#10 Hex Nut
Back of unit

Figure 2-1. Installation of the Optional Mounting Brackets

2–3

CDM-Qx Satellite Modem
Installation

2.3

Revision 5
MN/CDMQx.IOM

Configuration
There are no internal jumpers to configure. All configuration is carried out entirely in
software. The unit should first be configured locally, using the front panel keypad and
display. The unit will ship with a default Viterbi 128 kbps, QPSK, Rate 3/4 configuration.
Refer to the ‘FRONT PANEL OPERATION’ chapter for details on how to fully
configure the unit for the desired operating parameters.
Note: The auto-sensing AC power supply does not require any adjustments. Simply plug
in the supplied line cord, and turn on the switch on the rear panel.

2.4

Select Internal IF Loop
Correct operation of the unit may be verified rapidly, without the need for externally
connected equipment, providing there are at least one modulator and one demodulator.
From the top-level menu, select CONFIG, then GROUP, then MODEM. This will
require a modulator to be above a demodulator in the chassis. Then go back to the toplevel menu; select TEST, then IF LOOP (refer to the ‘FRONT PANEL OPERATION’
chapter). The demod should synchronize, and the green RECEIVE TRAFFIC LED
should illuminate. If the unit does not pass this test, call the factory for assistance.

2.5

Connect External Cables
Having verified correct operation in IF loop, enter the desired configuration, and proceed
to connect all external cables. If difficulties occur, please call the factory for assistance.
Observe the following:
•

If modulators and demodulators are to be used without grouping them as a
modem, a data interface cable is required to plug into each unit. If a modulator
and demodulator are grouped as a modem, the modulator must be located above
the demodulator and a single data interface cable is used simply by connecting it
to the demodulator.

•

If a modulator, demodulator, or grouped (modem) is defined as a back up unit, a
data interface cable is not required to the unit or units.

Note: Each modulator has an output power level in the range -5 to -25 dBm (-5 to -45
dBm for L-Band). Even though there is a single IF output connector and a single IF input
connector, all four slots are hooked up by way of internal power splitters and summers.
If two modulators are turned on, the total power out will be 3 dB higher (assuming both
modulators are set to the same power level). If four modulators are turned on, the total
power out will be 6 dB higher (assuming all modulators are set to the same power level).

2–4

Chapter 3. FUNCTIONAL
DESCRIPTION

The modem has two fundamentally different types of interface: IF and Data.
•
•

The Data interface can be a bi-directional path, which connects with the
customer’s equipment (assumed to be the DTE) and the modem (assumed to be
the DCE).
The IF interface provides a bi-directional link with the satellite via the uplink and
downlink equipment.

Transmit data is received by the terrestrial interface where line receivers convert the
clock and data signals to CMOS levels for further processing. A small FIFO follows the
terrestrial interface to facilitate the various clocking and framing options. If framing is
enabled, the transmit clock and data output from the FIFO pass through the framer, where
the overhead EDMAC data is added to the main data. Otherwise, the clock and data are
passed directly to the Forward Error Correction encoder. In the FEC encoder, the data is
scrambled, differentially encoded, and then convolutionally encoded. Following the
encoder, the data is fed to the transmit digital filters, which perform spectral shaping on
the data signals. The resultant I and Q signals are then fed to the BPSK/QPSK/
8-PSK/16-QAM modulator. The carrier is generated by a frequency synthesizer, and the
I and Q signals directly modulate this carrier to produce an IF output signal.

3–1

CDM-Qx Satellite Modem
Functional Description

Revision 5
MN/CDMQx.IOM

The RX IF signal is translated and filtered at an intermediate frequency (IF) using the
coarse step synthesizer. This is mixed with a second synthesizer, resulting in the signal
being IF sampled with a high-speed analog to digital converter (A to D). The sampled IF
is then digitally split into an in-phase (I) and a quadrature (Q) component. An AGC
circuit keeps the desired signal level constant over a broad range of input levels. The I
and Q signals are then decimated to reduce the computation rate into the poly phase
matched filter. Carrier and clock recovery is performed on the baseband I and Q signals
after the matched filter. The resultant demodulated signal is fed, in soft decision form, to
the selected FEC decoder (which can be Viterbi, TCM, Reed-Solomon, or Turbo if
installed). After decoding, the recovered clock and data pass to the de-framer (if EDMAC
framing is enabled) where the overhead information is removed. Following this, the data
passes to the Plesiochronous/Doppler buffer, which has a programmable size, or
alternatively bypasses the buffer. From here, the receive clock and data signals are routed
to the terrestrial interface, and are passed to the externally connected DTE equipment.
Physically a modem chassis is comprised of three main card assemblies:
1. The first of these is the IF Backplane card, which includes the frequency
reference; power splitters, power summers, the FSK link and the IF Loop back
functions.
2. The second card is the Digital Back plane card. This routes all the control
signals, the data path switching, the carrier-in-carrier signals and power for all
modules.
3. The third is the M&C, which controls all functions in the unit.
Within the chassis are four slots, which allow any combination of modulators or
demodulators to be installed. If configured as a single modem, two plug-in cards
comprising a modulator and demodulator are required.
A Modulator card contains the transmit interface circuits, the framer, the encoder or
encoders and the signal processing functions of modulation.
A Demodulator card performs all of the signal processing functions of carrier search,
cancellation, demodulation, Forward Error Correction, the de-framer,
plesiochronous/Doppler buffer and the receive interface circuits.
Terrestrial data interface cards can be on the modulator cards or demodulator cards.
When a modulator and demodulator are grouped together, the data interface card can be
used for full-duplex data interface. When 1 up to 4 ports of E1 (with D&I) are needed the
Quad E1 Data Interface Module can be installed in slots 3 and 4.
Figure 3-1 shows a functional block diagram of the modem with either modulators and
demodulators in all 4 slots and the figure also shows a modulator in slot 1 and a
demodulator in slot 2 along with a Quad E1 Data Interface Module in slot 3 and 4.

3–2

CDM-Qx Satellite Modem
Functional Description

Revision 5
MN/CDMQx.IOM

Figure 3-1. Modem Block Diagram

3–3

CDM-Qx Satellite Modem
Functional Description

Revision 5
MN/CDMQx.IOM

Notes:

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3–4

Chapter 4. EXTERNAL
CONNECTIONS

4.1

Introduction
The modem is constructed as a 1RU high rack-mounting chassis, which can be
freestanding, if desired. Rack handles at the front facilitate removal from and placement
into a rack. Figure 4-1 shows the front panel of the modem.

Figure 4-1. Front Panel

4–1

CDM-Qx Satellite Modem
External Connections

4.2

Revision 5
MN/CDMQx.IOM

Front Panel

LED
Keypad
Indicators

Display (VFD)

The Modem front panel features a Vacuum Fluorescent Display (VFD), a keypad, and
eight LED indicators. The user enters data via the keypad, and messages are displayed on
the VFD. The LEDs indicate, in a summary fashion, the status of the selected module.
The VFD is an active display showing 2 lines, each of 40 characters. It produces a blue
light, the brightness of which can be controlled by the user. It has greatly superior
viewing characteristics compared to a Liquid Crystal Display (LCD), and does not suffer
problems with viewing angle, contrast or temperature.
The keypad has six individual keyswitches, mounted directly behind a fully sealed
membrane overlay. They have a positive ‘click’ action, which provides the user with
tactile feedback. These six switches are identified as [↑], [↓], [→], [←] arrows, ENT and
CLR. The functions of these keys are described in the ‘FRONT PANEL
OPERATION’ section.
There are eight LEDs on the front panel. The behavior of these LEDs is described in the
‘FRONT PANEL OPERATION’ section.
A USB Slave connector is provided on the front panel. This feature
allows the user to reflash firmware.
IMPORTANT

4–2

CDM-Qx Satellite Modem
External Connections

4.3

Revision 5
MN/CDMQx.IOM

Rear Panel
The rear panel can be customized to meet the customer’s requirements. Figure 4-2 shows
three configurations that are available. Table 4-1 lists these connectors and Figure 4-2
shows the locations.
Figure 4-2. Rear Panel
Prime Power & Control

Slot 1
Slot 2

Slot 3
Slot 4

IF I/O

Configuration #1 Modem 1 with G.703 T1/E1 Balanced (DB-15)
Modem 2 with EIA-422 (DB-25)

Configuration #2 Modem 1 with G.703 T1/E1 Unbalanced (BNC)
Modem 2 with EIA-422 (DB-25)

Configuration #3 Modem 1 with G.703 T1/E1 Balanced (DB-15) and
Quad E1 Interface Module, 1-4 Ports of E1,with D&I (2) DB-9F)

4–3

CDM-Qx Satellite Modem
External Connections

Revision 5
MN/CDMQx.IOM

Notes:
1. One interface per Modem (i.e. Modulator and Demodulator card combination) or one interface
per Modulator card and Demodulator card are required if used independently.
2. When grouping a modulator and demodulator together to use as a modem, the modulator must be
located above the demodulator.
3. For redundant operation the backup unit does not need an interface.
4. For redundant operation the backup unit needs to be located in the lower right hand slot (#4) for
single module redundancy. For modem redundancy the backup units must be located in the right
hand slots (#3 & #4).
5. In the example Configuration #1 above, because all modules have interfaces, the following
configurations are possible.
a. Two independent modulators - one with a G.703 balanced and the other with an EIA-530
interface, with two independent demodulators one with a G.703 balanced and the other
with an EIA-530 interface.
b. Two independent modems - one with a G.703 balanced and the other with an EIA-530
interface (located on the demodulators).
c. A 1:1 redundant modem, with the online unit configured with a G.703 interface. The off
line modules will provide the backup even with a different interface.
6. In the example Configuration #3 above, the Quad E1 Interface Module is used in slot 3 and 4.
The modulator in slot 1 is grouped with the demoduletor in slot 2. This unique combinations
allows the user to select the Quad E1 interface or the data interface located in the modulator or
demodulator.

4–4

CDM-Qx Satellite Modem
External Connections

Revision 5
MN/CDMQx.IOM

Table 4-1. Modem Rear Panel Connectors
Name
Ref. Desig. Connector Type Function
Configuration #1 - Modem1 with G.703 T1/E1 Balanced (DB-15) Modem2 with EIA-422 (DB-25)
M&C 10/100BaseT
485/232
Slot #1 Mod:
Alarms
G.703
Slot #2 Demod:
Alarms
G.703
Slot #3 Mod:
Alarms
EIA-530
Slot #4 Demod:
Alarms
EIA-530
70/140 Tx /Rx:
Tx
Rx

RJ-45
9-Pin D Male

Remote Interface
Remote Interface

15-Pin Male
15-Pin Female

Form-C Alarms
Balanced G.703 Data Input

15-Pin Male
15-Pin Female

Form-C Alarms
Balanced G.703 Data Output, or Input/Output

15-Pin Male
25-Pin Female

Form-C Alarms
Data Input

15-Pin Male
25-Pin Female

Form-C Alarms
Data Output, or Input/Output

BNC

RF Output 75 or 50Ω

BNC

RF Input 75 or 50Ω

Ref
BNC
External Reference for Modem Synthesizers
AC Plug
IEC
Modem Power
Ground
#10-32 Stud
Grounding
Configuration #2 - Modem 1 with G.703 EIA-422(DB-25) Modem2 with G.703 T1/E1 Unbalanced (BNC)
M&C 10/100BaseT
485/232
Slot #1 Mod:
Alarms
G.703
Slot #2 Demod:
Alarms
G.703
Slot #3 Mod:
Alarms
EIA-530
Slot #4 Demod:
Alarms
EIA-530
70/140 Tx /Rx:
Tx
Rx
Ref
AC Plug
Ground

RJ-45
9-Pin D Male

Remote Interface
Remote Interface

15-Pin Male
BNC

Form-C Alarms
Unbalanced G.703 Data Output (incorrect slot for IO)

15-Pin Male

Form-C Alarms

BNC

Unbalanced G.703 Data input

15-Pin Male
25-Pin Female

Form-C Alarms
Data Input

15-Pin Male
25-Pin Female

Form-C Alarms
Data Output, or Input/Output

BNC

RF Output 75 or 50Ω

BNC

RF Input 75 or 50Ω

BNC
IEC
#10-32 Stud

External Reference for Modem Synthesizers
Modem Power
Grounding

4–5

CDM-Qx Satellite Modem
External Connections

Name

Revision 5
MN/CDMQx.IOM

Ref. Desig.

Connector Type Function

Configuration #3 - Modem 1 with G.703 T1/E1 Balanced (DB-15) and Quad E1IInterface (1-4 Ports E1,w/ D&I)
M&C 10/100BaseT
RJ-45
Remote Interface
485/232
9-Pin D Male
Remote Interface
Slot #1 Mod:
Alarms
15-Pin Male
Form-C Alarms
G.703
BNC
Unbalanced G.703 Data Output (incorrect slot for IO)
Slot #2 Demod:
Alarms
15-Pin Male
Form-C Alarms
G.703
BNC
Unbalanced G.703 Data input
Slot #3 and #4 Quad E1:
Ports 1-2 of E1
DB-9 Female
Balance E1 (with D&I)
Ports 3-4 of E1
DB-9 Female
Balance E1 (with D&I)
Ext Ref E1 Clock
DB-9 Female
Balance E1 clock input and output
70/140 Tx /Rx:
Tx
BNC
RF Output 75 or 50Ω
Rx
Ref
AC Plug
Ground

BNC

RF Input 75 or 50Ω

BNC
IEC
#10-32 Stud

External Reference for Modem Synthesizers
Modem Power
Grounding

4–6

CDM-Qx Satellite Modem
External Connections

Revision 5
MN/CDMQx.IOM

Note: The European EMC Directive (EN55022, EN50082-1) requires using properly shielded cables for
DATA I/O.

4.4

Chassis Connections

4.4.1

USB Port
This port is used to reflash firmware.

For continued operator safety, always replace the fuses with the correct type and
rating.
IMPORTANT

4.4.2

M&C 10/100BaseT Connector
The M&C 10/100BaseT connector is an 8-pin RJ-45 10/100BaseT Ethernet port
providing access to the modem’s management functions.

4.4.3

485/232 Connector
The 485/232 connectors are a 9-pin 'D' type male (DB9-M). Access is provided to remote
control ports of the modem, using both RS-232 and RS-485.
Table 4-2. Remote Control Interface Connector Pin Assignments
Pin #
1
2
3
4
5
6
7
8
9

Description
Ground
RS-232 TX Data
RS-232 RX Data
Reserved - do not connect to this pin
Ground
RS-485 RX Data B *
RS-485 RX Data A *
RS-485 TX Data B
RS-485 TX Data A

*Use for 2-wire RS-485 operation

4–7

Direction
Out
In

In
In
Out
Out

CDM-Qx Satellite Modem
External Connections

4.4.4

Revision 5
MN/CDMQx.IOM

Alarms Connector
All modules contain an alarm connector. The Alarms connector is a 15-pin 'D' type male
(DB15 M). This provides the user with access to the Form-C relay contacts, which
indicate the fault status of the unit. These are typically connected to an external fault
monitoring system, often found in satellite earth stations.
For a Modulator, TX fault and Unit Fault are supported. The transmit I and Q modulator
samples are available on this connector. Connecting these signals to an oscilloscope in
X,Y mode will provide the modulator signal constellation diagram, which is a useful
diagnostic aid. A pin also is provided which can mute the transmit carrier. This requires
that the pin be shorted to ground, or a TTL ‘low’.
For a Demodulator, RX fault and Unit Fault are supported. If a Modulator and
Demodulator are vertically grouped together as a modem, TX fault and the External
carrier off pin will also be supported. The receive I and Q demodulator samples are
provided on this connector. Connecting these signals to an oscilloscope in X,Y mode will
provide the receive signal constellation diagram, which is a useful diagnostic aid. As an
aid to antenna pointing, or for driving step-track equipment, an analog AGC signal is
provided on Pin 2 of this connector.
Table 4-3. Alarm Interface Connector Pin Assignments
Pin #
8
15
7
14
6
13
5
12
4
11
3
10
2
9
1

Signal Function
RX Traffic (De-energized, Faulted)
RX Traffic (Energized, No Fault)
RX Traffic
TX Traffic (De-energized, Faulted)
TX Traffic (Energized, No Fault)
TX Traffic
Unit Fault (De-energized, Faulted)
Unit Fault (Energized, No Fault)
Unit Fault
I Channel (Constellation monitor)
Q Channel (Constellation monitor)
No Connection
AGC Voltage (Rx signal level, 0 to 2.5 volts,
demodulator only)
EXT Carrier OFF (modulator or modulator and
demodulator grouped together)
Ground

4–8

Name
RX-NC
RX-NO
RX-COM
TX-NC
TX-NO
TX-COM
UNIT-NC
UNIT-NO
UNIT-COM
TX or RX-I
TX or RX-Q
N/C
AGC
EXT-OFF
GND

CDM-Qx Satellite Modem
External Connections

4.4.5

Revision 5
MN/CDMQx.IOM

Balanced G.703 Connector Tx/Rx Connector
The Balanced G.703 connection is a 15-pin female connector located on the rear
mounting plate of the modulator or demodulator. If a Modulator and Demodulator are
vertically grouped together as a modem, the data interface connector on the Demodulator
switches to duplex. This feature allows a single data interface connection to be used for a
modem instead of needing a “Y” cable. Otherwise, each module is a simplex data
interface. Refer to Table 4-4 for pin assignments.
Table 4-4. Balanced G.703 Interface Connector Pin Assignments
Pin #
1
9
2
10
3
11
4
12
5
13
6
14
7
15
8

4.4.6

Signal Function
Drop Data Input ( - )
Drop Data Input (+)
Ground
Not Used
Insert Data Output ( - )
Insert Data Output (+)
Ground
Drop Data Output ( - )
Drop Data Output (+)
Insert Data Input ( - )
Insert Data Input (+)
Not Used
Not Used
Not Used
Not Used

Name
DDI–
DDI+
GND
IDO–
IDO+
GND
DDO–
DDO+
IDI–
IDI+

Direction
In
In

Out
Out
Out (D&I Only)
Out (D&I Only)
In (D&I Only)
In (D&I Only)

Unbalanced G.703 Tx/Rx Connectors
Two female BNC 75Ω connectors are available for unbalanced operation at the G.703
data rates of T1 (1.544 Mbps) and E1 (2.048 Mbps). If a Modulator and Demodulator are
vertically grouped together as a modem, the Tx data input interface connector on the
Demodulator becomes active, allowing duplex operation. Otherwise, the Tx data input
connector is used on the modulator and the Rx data output connector is used on the
demodulator.

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CDM-Qx Satellite Modem
External Connections

4.4.7

Revision 5
MN/CDMQx.IOM

RS-530 Data Interface Connector
The Data connector is a 25-pin ‘D’ type female (DB-25F). This connector conforms to
the RS-530 pinout, which allows for connection of different electrical standards,
including EIA-422, V.35, and EIA-232.

IMPORTANT

All data interfaces are duplex! They will only operate as duplex if a
Modulator and Demodulator are vertically grouped together as a modem. In
that case the data interface connector on the Demodulator switches to duplex.
This feature allows a single data interface connection to be used for a modem
instead of needing a “Y” cable. Otherwise, the data interface for each module
will only operate as simplex.
It is the responsibility of the user to provide the appropriate cables to connect
to this RS-530 connector.
Table 4-5. RS-530 Data Interface Connector Pin Assignments

Pin #
2
14
24
11
15
12
3
16
17
9
8
10
23
7
1

Generic Signal
Description
TX Data A
TX Data B
TX Clock A
TX Clock B
INT TX Clock A
INT TX Clock B
RX Data A
RX Data B
RX Clock A
RX Clock B
Receiver Ready A
Receiver Ready B
External Carrier Off
(RS-232 ‘1' or TTL ‘low’ )
Signal Ground
Shield

V.35

RS-232

Circuit #

DTE to Modem
DTE to Modem
DTE to Modem
DTE to Modem
Modem to DTE
Modem to DTE
Modem to DTE
Modem to DTE
Modem to DTE
Modem to DTE
Modem to DTE
Modem to DTE

RS-422
RS- 530
LVDS
SD A
SD B
TT A
TT B
ST A
ST B
RD A
RD B
RT A
RT B
RR A
RR B

SD A
SD B
SCTE A
SCTE B
SCT A
SCT B
RD A
RD B
SCR A
SCR B
RLSD *
-

BA
DA
DB
BB
DD
CF
-

103
103
113
113
114
114
104
104
115
115
109
109

DTE to Modem

SG
Shield

SG
FG

AB
AN

102
101

Direction

Notes:
1. Receiver Ready is an RS-232 -level control signal on a V.35 interface
2. DO NOT connect signals to pins which are not shown - these pins are reserved for use by the redundancy
system
3. ‘B’ signal lines are not used for RS-232 applications
4. For X.21 operation, use the EIA-422 pins, but ignore RX Clock if the Modem is DTE, and ignore TX clocks if
the Modem is DCE.

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CDM-Qx Satellite Modem
External Connections

4.4.8

Revision 5
MN/CDMQx.IOM

Quad E1 Data Interface Connectors
The (2) Data connectors on the Quad E1 interface card are 9-pin ‘D’ type female (DB9F). Refer to Table 4-xx for pin assignments. J1 and J2 are shown below. Also available
is an adapter y-cable to adapt the DB9 to (2) RJ45 jacks, (part number PL/xxxTBD), see
Table xx and figure xx.
Table 4-xx6. Quad E1 Data Interface J1 Connector Pin Assignments
Pin #
5
9
4
8
3
7
2
6
1

Signal Function
DDI (+)
DDI (-)
IDO (+)
IDO (-)
Ground
DDI (+)
DDI (-)
IDO (+)
IDO (-)

Name
Port1_Tx+
Port1_Tx–
Port1_Rx+
Port1_Rx–
Gnd
Port2_Tx+
Port2_Tx–
Port2_Rx+
Port2_Rx–

Direction
In
In
Out
Out
In
In
Out
Out

Table 4-xx7. Quad E1 Data Interface J2 Connector Pin Assignments
Pin #
5
9
4
8
3
7
2
6
1

Signal Function
DDI (+)
DDI (-)
IDO (+)
IDO (-)
Ground
DDI (+)
DDI (-)
IDO (+)
IDO (-)

Name
Port3_Tx+
Port3_Tx–
Port3_Rx+
Port3_Rx–
Gnd
Port4_Tx+
Port4_Tx–
Port4 Rx+
Port4_Rx–

Direction
In
In
Out
Out
In
In
Out
Out

Table 4-xx8. Ext Ref Clock Interface J3 Connector Pin Assignments
Pin #
5
9
4
8
3
7
2
6
1

Signal Function
E1 Ref Clock In (+)
E1 Ref Clock In (-)
Not used
Not used
Ground
Not used
Not used
E1 Ref Clock Out (+)
E1 Ref Clock Out (-)

Name
Ref_Clk_In (+)
Ref_Clk_In (+)
--Gnd
--Ref_Clk_Out (+)
Ref_Clk_Out (+)

4–11

Direction
In
In
----Out
Out

CDM-Qx Satellite Modem
External Connections

4.4.9

Revision 5
MN/CDMQx.IOM

RX and TX IF Connectors
The IF connectors will depend on the configuration ordered. The following reflects
configurations available. BNC 75Ω is standard for 70/140MHz IF, N-Type 50Ω for LBand, and BNC Ref Connector. This 50Ω BNC female connector provides an external
reference input for the Tx and Rx IF synthesizers, and for the internal transmit clock.
The load impedance is 60.4Ω, so the VSWR is less than 1.25:1 at either 50Ω or 75Ω.
Input level is 0 dBm minimum to +20 dBm maximum at either 1, 2, 5, 10, or 20 MHz.
When external reference is enabled, the internal 10 MHz reference oscillator is phase
locked to the external reference input by a 10Hz bandwidth PLL. If no activity is present
at the external reference input, the modem will revert to the internal 10 MHz reference.

4.5

AC Power Connector
A standard, detachable, non-locking, 3-prong power cord (IEC plug) supplies the
Alternating Current (AC) power to the modem. Observe the following:
AC Power Specifications
Input Power
290W maximum, 57W typical without BUC power supply.
Input Voltage
100 - 240 volts AC, +6%/-10% - autosensing
(total absolute max. range is 90 to 254 VAC)
Connector Type
IEC
Fuse Protection
3.15A Slow-blow
Line and neutral fusing
20 mm type fuses

4.6

DC Power Connector
A standard, 3-screw terminal block supplies the Direct Current (DC) power to the
modem. Observe the following:
AC Power Specifications
Input Power
290W maximum, 57W typical without BUC power supply.
Input Voltage
36 to 72 VDC; 6.25 amps
Connector Type
Terminal Block
Fuse Protection
3.15A Slow-blow
20 mm type fuses

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External Connections

4.7

Revision 5
MN/CDMQx.IOM

Ground Connector
A #10-32 stud on the rear panel of the modem is used for connecting a common chassis
ground among equipment.
Note: The AC power connector provides the safety ground.

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External Connections

Revision 5
MN/CDMQx.IOM

This page is intentionally left blank.

4–14

Chapter 5. FRONT PANEL
OPERATION

5.1

Introduction

Figure 5-1. Front Panel Display
The user can fully control and monitor the operation of the Modem from the front panel
(Figure 5-1), using the keypad and display. Nested menus are used, which display all
available options, and prompt the user to carry out a required action.
The display has two lines of 40 characters each. The display is divided into two areas.
•

•

The left hand area briefly describes the contents of the four plug-in slots and
indicates which slot is currently being addressed. To navigate between sides is
as simple as selecting a slot if the curser is on the left side and being in the root
menu on the left side and arrowing to the left.
The right hand side accesses the addressed plug-in device. To group a modulator
and demodulator together requires the modulator to be located above the
demodulator, one of the two modules needs to be selected in the left side of the
screen, return to the right side of the screen go to Config, Group, Modem, and
select Group.

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CDM-Qx Satellite Modem
Front Panel Operation

Revision 5
MN/CDMQx.IOM

On most menu screens, the user will observe a flashing solid block cursor, which blinks
at a once-per-second rate. This indicates the currently selected item, digit, or field. Where
this solid block cursor would obscure the item being edited (for example, a numeric field)
the cursor will automatically change to an underline cursor.
If the user were to display the same screen for weeks at a time, the display could become
‘burnt’ with this image. To prevent this, the unit has a ‘screen saver’ feature that will
activate after 1 hour. The top line of the display will show the Circuit ID (which can be
entered by the user) and the bottom line will show the circuit Eb/No value (if there is a
demod and it is locked) followed by ‘Press any key....’. The message moves from right to
left across the screen, then wraps around. If there are multiple circuits, their messages and
Eb/No’s will be displayed sequentially. Pressing any key will restore the previous screen.
The behavior of the front panel LEDs is described below in Table 5-1.
Table 5-1. Front Panel LED Indicators
LED

Color
Red
Green

Unit
Status

Green
Off

Transmit
Traffic

Green
Receive
Traffic

Off
Green

Online

Off

Orange

Stored Event

Off
Orange
Off
Flashing

Remote

Orange
EDMAC Mode
Off
Orange
Test Mode
Off

IMPORTANT

Condition
A Unit Fault exists (Example: PSU fault)
No Unit Faults
Note: Unit fault does not include Tx or Rx fault.
No Tx Traffic Faults
A Tx Traffic fault exists or the Tx Carrier is in OFF state
Note: This LED corresponds to the selected slot, example .
No Rx Traffic Faults (demod and Viterbi decoder are locked, everything is OK)
An Rx Traffic fault exists (the demod may still be OK – check the fault status of the
unit from the Monitor menu).
Note: This LED corresponds to the selected slot, example .
The Unit is On Line, and carrying traffic
The Unit is Off Line (standby) - forced by externally connected 1:1 or 1:N
redundancy system
Note: This LED corresponds to the selected slot, example .
There is a Stored Event in the log, which can be viewed from the front panel, or
retrieved via the remote control interface
There are no Stored Events
The Unit is in Remote Mode - local monitoring is possible, but no local control
The Unit is in Local Mode - remote monitoring is possible, but no remote control
ODU FSK control has been enabled, and there is a communications fault.
Framing on, EDMAC on, and unit defined as Slave - local monitoring is possible,
but no local control
Either the unit is in Transparent mode (no framing), or the framing has been
selected, but in AUPC-only mode, or EDMAC Master configuration.
A Test Mode is selected (example: IF Loopback), or BERT Generator is turned on,
or BERT Monitor is turned on, or Spectrum Analyzer is turned on.
There is no Test Mode currently selected, BERT Generator is off, BERT Monitor is
off, and spectrum Analyzer is off.

In general, the Alarm relay state will reflect the state of the Front Panel LEDs. For instance, if
the Unit Status LED is red, the Unit Alarm relay will be active, etc. The one exception is the
Transmit Traffic relay. This will only be activated if a Transmit Traffic Fault exists – it does not
reflect the state of the TX carrier.

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CDM-Qx Satellite Modem
Front Panel Operation

Revision 5
MN/CDMQx.IOM

The keypad is shown in Figure 5-2:

Diamond Keypad (Presently used on all Units)

Button Keypad (New Configuration for Units)

Figure 5-2. Keypad
The function of these keys is as follows:

IMPORTANT

ENT
(Enter)

This key is used to select a displayed function or to execute a
modem configuration change.

CLR
(Clear)

This key is used to back out of a selection or to cancel a
configuration change, which has not been executed using ENT.
Pressing CLR generally returns the display to the previous
selection.

← →
(Left, Right)

These arrows are used to move to the next selection or to move the
cursor position. Most of the menus (space permitting) include arrow
key hints to guide the user.

↑ ↓
(Up, Down)

These arrows are used primarily to change configuration data
(numbers), at the current cursor position. Occasionally they may be
used to scroll through a number of choices at the current cursor
position. Most of the menus (space permitting) include arrow key
hints to guide the user.

The keypad has an auto-repeat feature. If a key is held down for more than 1 second, the key
action will repeat, automatically, at the rate of 15 keystrokes per second. This is particularly
useful when editing numeric fields, with many digits, such as frequency or data rate.

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CDM-Qx Satellite Modem
Front Panel Operation

5.2

Revision 5
MN/CDMQx.IOM

Left-Hand Display Area
The left side of the display (or slot screen) efficiently indicates what is in the four plug-in
slots and which slot is currently being addressed.
Four ungrouped plug-ins are displayed as in this example:

TX
RX

| (right hand display area)
| (right hand display area)

This display indicates modulators in the top slots, and demodulators in the bottom. The
locations of the four indicators line up with the location of the four slots when viewed
from the back of the chassis. The left hand TX on the display corresponds with the top
left slot in the chassis when viewed from the back. An empty slot is left blank.
The left RX on the example display is highlighted. This is the selected slot. All monitor
functions (including the front panel LEDs) reflect the status of this slot. All parameters
selected from the menu tree while this slot is selected apply either to this slot or to
common functions. The menus for common functions appear redundantly in all four slots.
To change slots, move the cursor to the desired slot, and press enter.
The designator for a plug-in device with an unmasked failure has an F suffix:

TXF
RX

| (right hand display area)
| (right hand display area)

In this example, the upper right transmitter has a fault. (View the fault using Monitor,
Alarms, etc).

5.2.1

Modems
A modulator in a top slot can be grouped with a demodulator in the slot directly below it
to form a modem:

TX
RX

| (right hand display area)
| (right hand display area)

The example indicates a configuration in the right hand slots (when viewed from the back
of the chassis) grouped together to form a modem. Selecting the slots is the same as a
basic configuration except that the blank area below the MD are not be selectable. When
the modem is selected, the menus will display modulator and demodulator functions, and
the software will select the appropriate plug-in for the command.

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CDM-Qx Satellite Modem
Front Panel Operation

Revision 5
MN/CDMQx.IOM

Two modems can share a modem:

| (right hand display area)
| (right hand display area)

The selected modem is the modulator demodulator pair on the right side of the chassis
(when viewed from the back). When modem is in CnC™ mode, the brackets (<>) will
turn into bold characters.

5.2.2

Redundancy
Modules, (modulators and demodulators) can be upgraded to operate as redundant units.
If enabled the module can back up a like kind module located anywhere in the chassis. If
a modulator and demodulator have redundancy enabled and they are grouped as a
modem, the pair can back up a modem. Note: The interface selected for the modules
does not have to match the interface type used on the prime modules.
Three redundancy modes are possible with a modem. Back-up devices are notated with a
B suffix while the designated prime modules (non-modem grouped) are noted with P
suffix. In a non-modem configuration, the back-up device must be installed in slot #4. If a
backup device has failed, the B suffix and the F suffix will alternately display.
1:1 redundant modems look similar to the two-modem example. The modems have
independent monitor functions, but configuring the prime modem will configure the back
up modem.

| (right hand display area)
| (right hand display area)

In this example, the backup modem is selected.
1:2 and 1:3 modulators or demodulators look similar to the basic display. A backup
modulator or demodulator will back up all compatible modulators or demodulators in the
chassis designated as primes.
The Online LED together with the selection bracket (<>) is used to indicate which device
is online.

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CDM-Qx Satellite Modem
Front Panel Operation

5.2.3

Revision 5
MN/CDMQx.IOM

Spectrum Analyzer
The built-in spectrum analyzer mode is available, accessible via remote control, front
panel or web browser. When it is active, the selected demod will not respond to specific
Rx front panel settings, nor will it carry traffic. It is marked with an S suffix. It has it’s
own front panel menu controls under “Test” menu.

TX
RXS

| (right hand display area)
| (right hand display area)

In this example, the bottom right receiver (as seen from the back of the chassis) is being
used as a spectrum analyzer. Only one Rx is allowed to enable spectrum analyzer in a
chassis. To view the spectrum, the user needs a Windows application from Comtech or a
web browser.

5.3

Right-Hand Display Area
Figure 5-3 shows the menu structure similar to the CDM-570L. The menus are shown
fully populated, but if the addressed plug-in device is a modulator or a demodulator,
much of the menu tree will be locked out. Functions that are not tied to a plug-in slot
(like the external reference) are displayed no matter which slot is addressed.
The detailed screens and menus are as follows.

5.4

Accessing the Display Area
Since the front panel display screen is split into two, the left-hand display area (also
called as the slot screen) can be accessed by using ◄ arrow key if the menu-level is
MAIN, CONFIG, MONITOR, or INFO (and there is more than one module to select
between).
To go back to the right-hand display area (also called the menu screen), just press CLR
or ENT. By pressing ENT, the user has selected the plug-in card.

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CDM-Qx Satellite Modem
Front Panel Operation

Para
5.5
5.6
5.61
5.6.1.1
5.6.1.2
5.6.1.3
5.6.1.4
5.6.1.5
5.6.1.6
5.6.1.7
5.6.1.8
5.6.1.9
5.6.2
5.6.2.1
5.6.2.2
5.6.2.3
5.6.2.4
5.6.2.5
5.6.2.6
5.6.2.7
5.6.3
5.6.4
5.6.5
5.6.6
5.6.7

Title
Opening Screen
Main Menu
Conf:
Config → Remote
Config → Tx
Config → Rx
Config → Group
Config → Frame
Config → Interface
Config → Ref
Config → Mask
Config → ODU
Monitor
Monitor → Alarms
Monitor → Rx-Params
Monitor → Event-Log
Monitor → Stats
Monitor → AUPC
Monitor → CnC
Monitor → ODU
Test
Info
Save/Load
Utility
Utility→FAST

Revision 5
MN/CDMQx.IOM

Remarks
Select: Config; Monitor; Test; Info; Save/Load; Util; ODU
Select: Remote; Tx; Rx; Group; Frame; Interface; Ref; Mask; ODU
Select: Local; Serial; Ethernet
Select: FEC; Mod; Code; Data; Freq; On/Off; Pwr; Scram; Clk; Inv; Txα
Select: FEC; Demod; Code; Data; Freq; Acq; Descram; Buf; Inv; Misc; CNC
Select: Modem; Redundancy
Select: Unframed; EDMAC; EDMAC-2; D&I++
Select: RS422; V.35; RS232; HSSI; ASI; G.703; QDI; None
Select: Internal; 10MHz
Select: Transmit; Receive; Reference; BUC; LNB
Select: BUC; LNB
Select: Alarms; Rx-Params; Event-Log; Stats; AUPC; CNC; ODU
Select: Transmit; Receive; Unit; ODU
Select: Eb/No, BER, ΔF, BUF, RSL
Select: View; Clear-All
Select: View; Clear-All; Config
Framing is required for AUPC Monitor
Carrier in Carrier® (CnC) is not locked.
Select: ODU; LNB
Select: Mode; BIST; Spec-Analyzer
Select: Rem; Tx; Rx; Buffer; Frame; Interface; Mask; Ref; ID
Select: Save; Load
Select: RxBuffer; Clock; Ref; ID; Display; Firmware; FAST
Select: Base; Slot1; Slot2; Slot3; Slot4

Figure 5-3. Principle Menu Tree

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CDM-Qx Satellite Modem
Front Panel Operation

5.5

Revision 5
MN/CDMQx.IOM

Opening Screen
Comtech EF Data CDM-Qx
Firmware Version: 1.1.1
This screen is displayed whenever power is first applied to the unit (70/140 MHz
version). The word “CDM-Qx” will be replaced with “CDM-QxL” for L-Band units.
Pressing any key will take the user to the top-level selection screen:

5.6

TOP LEVEL SELECTION
MAIN MENU:
Test Info

Config
Monitor
Save/Load Util ODU

The user is presented with the following choices:
Config

(Configuration) This menu branch permits the user to fully configure the
unit.

Monitor

This menu branch permits the user to monitor the alarm status of the unit,
to view the log of stored events, and to display the Receive Parameters
screen.

Test

This menu branch permits the user to invoke one of several test modes
(loopbacks, for example).

Info

(Information) This menu branch permits the user to view information on
the unit, without having to go into configuration screens.

Save/Load

This menu branch permits the user to save and to retrieve up to 10
different modem configurations.

Util

(Utility) This menu branch permits the user to perform miscellaneous
functions, such as setting the Real-time clock, adjusting the display
brightness, etc. For L-Band unit, the menu “Util” will be replaced with
“Utility”.
This menu permits the user to monitor and control Comtech CSAT and
KST transceivers.

ODU
(70/140 MHz only)

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Front Panel Operation

5.6.1

Revision 5
MN/CDMQx.IOM

CONFIG
The sub-branches available are:

CONFIG: Remote Tx Rx Group
Frame Interface Ref Mask ODU

Remote

(Remote Control) This menu sub-branch permits the user to define whether
the unit is being controlled locally, or remotely.
NOTE: The unit may be monitored over the remote control bus at any time.
When in Local mode, however, configuration parameters may only be
changed through the front panel. Conversely, when in Remote mode, the unit
may be monitored from the front panel, but configuration parameters may
only be changed via the remote control bus.

(Transmit) This menu sub-branch permits the user to define, on a parameterby-parameter basis, the transmit configuration of the unit.

(Receive) This menu sub-branch permits the user to define, on a parameterby-parameter basis, the receive configuration of the unit.

Group

This menu sub-branch permits the user to group a vertically aligned
modulator and demodulator into a modem, or to group any compatible plugins for redundancy.

Frame

This menu sub-branch permits the user to define if the unit should operate in
a transparent mode (no framing) or in a framed mode. In the framed mode
(EDMAC), an overhead of 5% is added to the rate transmitted over the
satellite so that M&C information may be passed to the distant end.

Interface

(Interface) This menu sub-branch permits the user to define which electrical
interface type is active at the data connectors.

Ref

(Reference) This menu sub-branch permits the user to define whether the
unit should use its own internal 10MHz reference, or phase lock to an
externally applied reference, and if so, at what frequency. If the internal
reference is selected, it can optionally drive the connector.

Mask

This menu sub-branch permits the user to mask certain traffic alarms, which
may cause problems to the user. As an example, certain multiplexers use ‘all
ones’ as an idle pattern. However, by convention, the ‘all ones’ condition is
taken to be the Alarm Indication Signal (AIS). The CDM-Qx monitors for the
AIS condition, and if desired, this alarm may be masked.

ODU
(L-Band unit
only)

(Outdoor Unit) This menu sub-branch permits the user to configure externally
connected Low-noise Block Down Converter (LNB) and/or Block Up
Converter (BUC) for L-Band units.

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CDM-Qx Satellite Modem
Front Panel Operation

5.6.1.1

Revision 5
MN/CDMQx.IOM

(ConfigRemote) – REMOTE CONTROL
Select Local, Serial, or Ethernet using the (◄ ►)arrow keys, then press ENT.

Remote Control Entry: Local
Serial Ethernet
(◄ ►,ENT)
If Local is selected then remote control will be disabled. Remote monitoring is still
possible.

(ConfigRemoteSerial)
If Serial is selected:

Remote Serial Config:
Interface Baudrate (◄ ►,ENT)

(ConfigRemoteSerialInterface)
If Interface is selected:

M&C Serial Interface: RS232
RS485-2W RS485-4W (◄ ►,ENT)
Select RS232, RS485-2W (2-wire), or RS485-4W (4-wire), using the ◄ ► arrow keys,
then press ENT.
At this point the user will be further prompted to enter the bus address.
If RS232 is selected, the following menu is displayed:

In RS-232 Mode, Serial Bus
Base Address is fixed @ 0000

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Front Panel Operation

Revision 5
MN/CDMQx.IOM

(ConfigRemoteSerialInterfaceRS485) - RS-485 Bus
Address
However, if either RS-485 mode is selected, the user will be further prompted:

Edit RS-485 Serial Bus Base
Address: 0245
(◄ ►,▲▼,ENT)
Edit the RS-485 bus address of this unit. This is accomplished by selecting the digit to be
edited, using the efarrow keys. The value of the digit is then changed using the
dcarrow keys. The user should then press ENT. The valid range of addresses is from
1 to 9999.

(ConfigRemoteSerialBaudrate)
If the user selects Baud Rate, the user is presented with the following menu:

M&C Serial Bus Baud Rate:
19200 Baud
(▲ ▼,ENT)
Edit the baud rate of the remote control bus, connected locally to the M&C computer.
The value is changed using the cdarrow keys. The user should then press ENT. Values
of 2400, 4800, 9600, 19200, 38400, and 57600 baud
are possible.
Note that the asynchronous character format is FIXED at 8 data bits, 1 stop bit, no parity
(8-N-1).

(ConfigRemoteEthernet)
If Ethernet is selected:

Ethernet Config:
(◄ ►, ENT)
Gateway Address MAC SNMP

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Front Panel Operation

Revision 5
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(ConfigRemoteEthernetGateway)
If Gateway is selected, the submenu will display:

M&C Ethernet IP Gateway:
192.128.001.001
(◄ ►▲ ▼, ENT)
Edit the IP Gateway Address for the Ethernet M&C port for this unit. This is
accomplished by selecting the digit to be edited, using the ◄ ► arrow keys. The value
of the digit is then changed using the ▲ ▼ arrow keys. The user should then press ENT.

(ConfigRemoteEthernetAddress)
If Address is selected, the submenu will display:

M&C Ether IP Address/Range:
192.168.001.001/24 (◄ ►▲ ▼,ENT)
Edit the IP Address and Range for the Ethernet M&C port for this unit. This is
accomplished by selecting the digit to be edited, using the ◄ ► arrow keys. The value
of the digit is then changed using the STarrow keys. The user should then press ENT.

(ConfigRemoteEthernetMAC)
If MAC is selected, the user will only be allowed to view it as displayed for example:

M&C Port MAC Address:
00-06-B0-00-00-D5
This is a read-only window, which displays the factory program MAC address for the
Ethernet management interface.

(ConfigRemoteEthernetSNMP)
If SNMP is selected, the following sub-menu is displayed:

SNMP: Communities Traps
(◄ ►, ENT)

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(ConfigRemoteEthernetSNMPCommunities)
If Communities is selected:

SNMP Communities:
Read Write

(◄ ►, ENT)

If Read is selected, the following sub-menu is displayed:

Read Community:
public

(◄ ► ▲ ▼, ENT)

If Write is selected, the following sub-menu is displayed:

Write Community:
private

(◄ ► ▲ ▼, ENT)

Edit the SNMP Read or Write Community string using the ◄ ► and ▲ ▼ arrow keys.
Only the first 20 characters on the bottom line are available. The cursor selects the
position on the bottom line (◄ ►) and the character is then edited (▲ ▼). All printable
ASCII characters are available with the exception of backslash (ASCII code 92) and ~
(ASCII code 126). When the user has composed the string, press ENT. All trailing spaces
are removed from the Community string upon entering.

(ConfigRemoteEthernetSNMPTraps)
If Traps is selected, the following sub-menu is displayed:

Traps: Community Version
IP Addr#1 IP Addr#2 (◄ ►, ENT)

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If Community is selected, the following sub-menu is displayed.

Trap Community:
comtech

(◄ ► ▲ ▼, ENT)

Edit the Trap Community string using the ◄ ► and ▲ ▼ arrow keys. Only the first 20
characters on the bottom line are available. The cursor selects the position on the bottom
line (◄ ►) and the character is then edited (▲ ▼). All printable ASCII characters are
available with the exception of backslash (ASCII code 92) and ~ (ASCII code 126).
When the user has composed the string, press ENT. All trailing spaces are removed from
the Community string upon entering.
If Version is selected, the following sub-menu is displayed.

Trap Version:
SNMPv1 SNMPv2

(◄ ►, ENT)

Select SNMPv1 or SNMPv2, using the ◄ ► arrow keys, then press ENT.
If IP Addr#1 is selected, the following sub-menu is displayed:

Trap IP Addr#1:
000.000.000.000

(◄ ► ▲ ▼ ENT)

If IP Addr#2 is selected, the following sub-menu is displayed:

Trap IP Addr#2:
000.000.000.000

(◄ ► ▲ ▼ ENT)

These two IP Addresses are Trap Destination’s IP Addresses. Edit the IP Address by
using the ◄ ► and ▲ ▼ arrow keys. If both Trap IP Address are 000.000.000.000, it
means Trap is disabled.

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5.6.1.2

Revision 5
MN/CDMQx.IOM

(ConfigTx) - TRANSMIT
Tx: FEC Mod Code Data Freq
On/Off Pwr Scram Clk Inv Txα
Select FEC, Mod, Code, Data, Freq, On/Off, Pwr, Scram, Clk, Inv, or Txα using
the ◄ ► arrow keys, then press ENT. The user will then be taken to a further submenu. Each of these choices is described briefly in the table below:
FEC

Mod

Code

Data

Freq

On/Off
Pwr
Scram

Clk

Inv
Txα

IMPORTANT

(Forward Error Correction) This sub-menu permits the user to select the method of FEC used
for transmission (Viterbi, TPC, etc). FEC type takes the highest configuration priority.
(Modulation) This sub-menu permits the user to select the modulation type used for
transmission (BPSK, QPSK, 8-PSK, etc.). The available choice of modulation will depend on the
FEC type chosen.
(FEC Code Rate) This sub-menu permits the user to select the FEC Code Rate used for
transmission (Rate 1/2, Rate 3/4, etc). The available choice of Code Rate will depend on both
the FEC type and Modulation type selected.
(Data Rate) This sub-menu permits the user to select the transmit data rate, in steps of 1 bps.
The choice of data rate will depend on the FEC type, Modulation type, and Code Rate selected.
(Frequency) This sub-menu permits the user to select the transmit frequency, from 950 MHz to
1950 MHz, in steps of 100Hz for L-Band units, or from 50 MHz to 90 MHz and from 100 MHz to
180 MHz for 70/140MHz units.
This sub-menu permits the user to control the output state of the transmit carrier.
(Output Power level) This sub-menu permits the user to control the output level of transmit
carrier, either manually, or using the AUPC (Automatic Uplink Power Control) feature.
(Scrambler) This sub-menu permits the user to select whether or not data scrambling is used.
(Clock Source) This sub-menu permits the user to select the clock source for transmission. This
can be from the internal source, from an external source, or from the distant-end of the satellite
link (loop timed).
(Inversion) This sub-menu permits the user to invert the sense of the transmitted spectrum, or to
invert the sense of the transmitted baseband data or data clock
(α-Factor) This permits the user to select the modulator’s roll-off factor either 20% or 35%.

Modulation type ►

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Code Rate ►

Data Rate
(Lowest)

CDM-Qx Satellite Modem
Front Panel Operation

Revision 5
MN/CDMQx.IOM

If the user changes a parameter within this hierarchy, the other parameters may
become invalid. In this case, the software will change those other parameters, in
order that the configuration remains valid at all times.
Example: Suppose the user has selected Viterbi + Reed Solomon, QPSK, Rate
1/2. Now, the user changes the modulation type from QPSK to 16-QAM. In this
case, Rate 1/2 is no longer a valid code rate, and so it will be automatically
changed to the nearest valid code rate (Rate 3/4). Each of the configuration subbranches will now be described in detail.

(ConfigTxFEC) – TX FEC TYPE
Tx FEC: Vit Vit+RS TCM+RS
TPC
(◄ ►, ENT)

IMPORTANT

All possible choices are presented at all times. If an option is not installed
(either Hardware, or FAST) or not valid, the ◄ ► arrow keys will force the
cursor to skip past the unavailable choice.

FEC Type
Vit (Viterbi)
Vit+R-S (Viterbi +Concatenated
Reed-Solomon)
TCM+R-S (Trellis Coded
Modulation + Concatenated ReedSolomon)
TPC (Turbo)

RULES
Always valid
Always valid

COMMENT

If 8-PSK FAST is enabled

Fixed at 8-PSK and
Rate 2/3

If the TPC codec is installed

(ConfigTxMod) – MODULATION SCHEME
Modulation: BPSK QPSK 8-PSK
16-QAM
(◄ ►, ENT)

IMPORTANT

All possible choices are presented at all times. If an option is not installed
(either Hardware, or FAST) or valid , the ◄ ► arrow keys will force the
cursor to skip past the unavailable choice.

CASE
BPSK

RULES
Valid for all FEC types except TCM+R-S

QPSK

Valid for all FEC types except TCM+R-S

8-PSK

Valid for TCM+R-S, TPC (Turbo) requires 8-PSK FAST option

16-QAM

Valid for Viterbi + R-S, TPC (Turbo) requires 16-QAM FAST option

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MN/CDMQx.IOM

(ConfigTxCode) – TX CODE RATE
Tx Code Rate: 5/16 21/44 1/2
2/3 3/4 7/8 17/18
(◄ ►)

IMPORTANT

CASE
5/16
21/44
1/2
2/3
3/4
7/8
17/18

All possible choices are presented at all times. If an option is not installed
(either Hardware, or FAST) or valid, the ◄ ► arrow keys will force the
cursor to skip past the unavailable choice.
RULES
Valid for BPSK and Turbo
Valid for BPSK, QPSK and Turbo
Valid for BPSK, QPSK, Viterbi, Viterbi+R-S
Valid for TCM+R-S only (8-PSK)
Valid for QPSK, 8-PSK, and 16-QAM
Valid for QPSK, 8-PSK, and 16-QAM
Valid for QPSK, 8-PSK , and Turbo

(ConfigTxData) – TX DATA RATE
Tx Data Rate: 05000.000kbps
Sym:02500.000ksps
In Quad Drop&Insert (QDI) mode, these data rates are read-only! The data rate
will be the sum of the tributary rates for all ports. This also will show the
calculated symbol rate and Nx64kbps (where N=001 to 124).

IMPORTANT

The overall range of data rates is from 32 to 20000 kbps. The overall range of symbol
rates is up to 10000 ksps. The minimum data rate is set to 32 kbps only for BPSK and
QPSK, and the maximum data rates are dependent on modulation type and FEC
encoder rate. If the user changes the modulation or FEC, and the currently selected
data rate can no longer be supported, the data rate will be adjusted automatically, up or
down, keeping the symbol rate constant. The bottom line of the display shows the
symbol rate, based on FEC type, modulation, FEC Code Rate, and Data Rate. The
valid ranges of data rate are shown in the following table.

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MN/CDMQx.IOM

FEC Type
Viterbi

Modulation

Code Rate

BPSK

Rate 1/2

Data Rate Range

Viterbi

QPSK

Rate 1/2

32 kbps to 10 Mbps

Yes – see note below

Viterbi

QPSK

Rate 3/4

32 kbps to 15 Mbps

Yes – see note below

Viterbi

QPSK

Rate 7/8

32 kbps to 17.5 Mbps

Yes – see note below

Viterbi + R-S

BPSK

Rate 1/2

32 kbps to 4.5 Mbps

Yes – see note below

Viterbi + R-S

QPSK

Rate 1/2

32 kbps to 9.1 Mbps

Yes – see note below

Viterbi + R-S

QPSK

Rate 3/4

32 kbps to 13.7 Mbps

Yes – see note below

Viterbi + R-S

QPSK

Rate 7/8

32 kbps to 16 Mbps

Yes – see note below

Viterbi + R-S

16-QAM

Rate 3/4

349.1 kbps to 20 Mbps

Yes – see note below

Viterbi + R-S

16-QAM

Rate 7/8

407.3 kbps to 20 Mbps

Yes – see note below

TCM + R-S

8-PSK

Rate 2/3

232.7 kbps to 18.3 Mbps

Yes – see note below

TPC

BPSK

Rate 5/16

32 kbps to 3.1 Mbps

Yes – see note below

TPC

BPSK

Rate 21/44

32 kbps to 4.7 Mbps

Yes – see note below

TPC

QPSK

Rate 21/44

32 kbps to 9.5 Mbps

Yes – see note below

TPC

QPSK

Rate 3/4

32 kbps to 15 Mbps

Yes – see note below

32 kbps to 5 Mbps

EDMAC limited?
Yes – see note below

TPC

QPSK

Rate 7/8

32 kbps to 17.5 Mbps

Yes – see note below

TPC

QPSK

Rate 17/18

32 kbps to 18.888 Mbps

Yes – see note below

TPC

8-PSK

Rate 3/4

288 kbps to 20 Mbps

TPC

8-PSK

Rate 7/8

336 kbps to 20 Mbps

TPC

8-PSK

Rate 17/18

362.7 kbps to 20 Mbps

TPC

16-QAM

Rate 3/4

384 kbps to 20 Mbps

TPC

16-QAM

Rate 7/8

448 kbps to 20 Mbps

Important Note: Where noted in the table above, if EDMAC framing is employed, the upper data rate will be reduced
by 5% for data rates up to 2.048 Mbps, and by 1.6% for data rates above 2.048 Mbps, where EDMAC2 framing is
used, or for Rate 21/44 BPSK/QPSK Turbo, or Rate 5/16 BPSK Turbo.

Tx IF Freq: 1156.3456 MHz
(◄ ►,▲ ▼, ENT)

(ConfigTxFreq) – TX IF FREQUENCY
Edit the Transmit IF Frequency. This is accomplished by selecting the digit to be edited,
using the WXarrow keys. The value of the digit is then changed using the STarrow
keys. The user should then press ENT. The range of frequencies depends upon the plugin module. The above example shows the L-Band version of modem.

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MN/CDMQx.IOM

If (using the ODU, BUC menus) the user has selected a BUC LO frequency (other than
zero) and defined whether the mix is high side or low side, the display will be modified
as shown below, to include the calculated Transmit RF frequency of the modem/BUC
combination:

Tx IF Freq: 1156.3456 MHz
RF=14156.3456 (◄ ►▲ ▼ ENT)
As the Tx IF frequency is edited the RF frequency will automatically be updated

(ConfigTxOn/Off) – TRANSMIT ON/OFF CONTROL
Tx Output State: On Off
RxTxInhibit Common (◄ ►, ENT)
Select either On, Off, RxTxInhibit, or Common using the WXarrow keys, then press
ENTER.
When Rx-Tx Inhibit (RTI) is selected, it will prevent the TX carrier from being
transmitted, until the demodulator is locked.
To avoid the Tx Carrier from being turned off when the demodulator loses lock for a very
short period of time, the demodulator must be unlocked continuously for a period of 10
seconds before the transmit carrier is inhibited. This time interval is fixed and the user
cannot change it.

IMPORTANT

Having this feature enabled does not affect the internal IF Loopback feature.
But, please be aware that if an external IF Loopback is attempted (connecting
an external cable from the Tx IF output to the Rx IF input), then this will not
work! (The Tx carrier cannot turn on until the demod is locked, and the demod
cannot lock, because the TX output is off. The net result is that the demod will
not lock, and the Tx carrier will not turn on. USE THE RTI FEATURE WITH
EXTREME CARE!

When Common is selected, this sub-menu will appear:

Tx Common Output State:
Off On
(◄ ► ENT)
This will turn On or Off all the transmit path – master control for all modulators.

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(ConfigTxPwr) – TRANSMIT POWER LEVEL MODE
Select the output power level mode, either Manual or AUPC, then press ENT.

Output Power Level Mode:
Manual AUPC (◄ ►, ENT)
If the user selects Manual, the following menu is displayed:

(ConfigTxPwrManual) – MANUAL MODE
Tx Output Power Level:
-03.9 dBm
(◄ ►, ▲ ▼, ENT)
Edit the output power level using the ◄ ► and STarrow keys, then press ENT.
If the user selects AUPC, and ‘Framed’ mode is not selected, the following menu is
displayed:

Warning! AUPC needs
Framed Mode (ENT or CLR)
Pressing either ENT or CLR returns the user to the previous menu with Manual
selected.
If the user selects AUPC, and ‘Framed’ mode is selected, the following menu is
displayed:

(ConfigTxPwrAUPC) – AUPC MODE
Target-Eb/No Max-Range Alarm
DemodUnlock (◄ ►, ENT)
Select either Target EbNo, Max-Range, Alarm or Demod-Unlock using the W Xarrow
keys. The user should then press ENT.

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MN/CDMQx.IOM

(ConfigTxPwrAUPC) – TARGET Eb/No
Remote Demod - Target Eb/No
Min Eb/No:9.9dB (◄ ►, ▲ ▼, ENT)
Edit the target Eb/No of the remote demod, using the ◄ ► and STarrow keys.
Default value is 3.0 dB, and upper limit is 9.9 dB. The user should then press ENT.

(ConfigTxPwrAUPC) – MAX RANGE
Maximum-permitted Power
increase: 01dB (▲ ▼, ENT)
Edit the maximum permitted increase in power level (when in AUPC mode), using the
STarrow keys. Default value is 1dB, and upper limit is 9 dB. Then press ENT.

(ConfigTxPwrAUPC) – ALARM
Action when max Tx Power
reached: None TxAlarm (◄ ►,
Select the action that will occur if the AUPC causes the maximum output power level to
be reached, either None or TxAlarm. Then press ENT.

(ConfigTxPwrAUPC) – DEMOD-UNLOCK
Action when Remote Demod
unlocks: Nom-Pwr Max-Pwr
Select the action that will occur if the remote demod is unlocked. The choices are: NomPwr (Nominal Power), where the output level will revert to the nominal power level set
under Manual, or Max-Pwr, (Maximum Power), where the output level will change to
the maximum permitted. The user should then press ENT.

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MN/CDMQx.IOM

(ConfigTxPwrCombined) – COMBINED TRANSMIT POWER
Tx Combined Output Power:
-3.9 dBm
(◄ ►,▲ ▼,ENT)
The combined power adjusts the level after all modulators in the chassis have been
combined. It has a range of –5 dBm to +5 dBm. This level is fixed, and is not adjusted by
AUPC.

(ConfigTxScram) – SCRAMBLER
Scrambling:Default-On
IESS-315-On Off (◄ ►,ENT)
The options are:
Default-On
IESS-315-On
Off

the appropriate scrambler type is automatically selected
this only applies when Turbo is installed and has been selected as the FEC
type
No scrambling

As before, the options are displayed all of the time, but the ◄ ► arrow keys will force
the cursor to skip past an unavailable choice.
The default scrambler types are:
IMPORTANT

Viterbi, no framing:
Viterbi, EDMAC frame:
Viterbi + R-S or TCM/R-S:
TPC:

ITU V.35 (Intelsat variant)
Comtech proprietary, frame synchronized
Per IESS-308, frame synchronized
Comtech proprietary, frame synchronized

(ConfigTxClk) – TX CLOCKING MODE
Tx Clocking Mode: Int Ext
Loop-Timed ExtLoop (◄ ►,ENT)
Select Int (Internal), Ext (External) or Loop-Timed, using the ◄ ► arrow keys, then
press ENT.

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MN/CDMQx.IOM

Internal

indicates that the CDM-QX will supply a clock to the DTE, which is derived from its
internal high-stability source.

External

indicates that the CDM-QX expects to receive a clock from the DTE, to which the unit
can phase-lock its internal circuits. (If G.703 is selected as the Interface type, the
software will force the clock mode to External.)

LoopTimed

indicates that the transmit timing source should be the receive clock, from the
direction of the satellite. This is a useful mode, in that no external connection needs
to be made in this mode. If the demodulator loses lock, or if there is no receive signal
present, the internal clock is substituted. Note also that this mode will work even with
asymmetric Rx and Tx data rates.
Indicates that the CDM-Qx expects to receive a clock from the DTE, which is derived
from the received clock from the direction of the satellite. This is useful in CnC mode
with G.703 interface wherein the remote station is relying on a centralized clock from
the hub station.

ExtLoop

(ConfigTxInv) – TX INVERSION FUNCTIONS
Tx Inversion functions:
Spectrum Data Clock (◄ ►,ENT)
Select Spectrum or Data Clock, using the ◄ ► arrow keys, then press ENT.
If Spectrum is selected, the following sub-menu will be displayed:

Tx Spectral Inversion:
Normal Inverted
(◄ ►, ENT)
Select Normal or Inverted, using the ◄ ► arrow keys, then press ENT.
If Data Clock is selected, the following sub-menu will be displayed:

Tx Data Sense:
Normal Inverted

(◄ ►, ENT)

Select Normal or Inverted, using the ◄ ► arrow keys, then press ENT.
If Clock is selected, the following sub-menu will be displayed:

Tx Clock Inversion:
Normal Inverted
(◄ ►, ENT)

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(ConfigTxTxα) – TX Roll-Off (α) factor
Tx Roll-off: 20%

35%
(◄ ►, ENT)

Select 20% or 35%, using the ◄ ► arrow keys, then press ENT. The default is 35%.

5.6.1.3

(ConfigRx) - RECEIVE
The sub-branches available are:

Rx:FEC Demod Code Data Freq
Acq Descram Buf Inv Misc CnC
Select FEC, Dem, Code, Data, Frq, Acq, Descram, Buf, Inv, Misc, or CnC® using
the WXarrow keys, then press ENT. The user will then be taken to a further sub-menu.
Each of these choices is described briefly in the table below:
FEC

Demod

Code

Data

Acq
On/Off
Descram

(Forward Error Correction) This sub-menu permits the user to select the method of
FEC used for reception (Viterbi, TPC, etc.). FEC type takes the highest configuration
priority.
(Demodulation) This sub-menu permits the user to select the modulation type used for
reception (BPSK, QPSK, 8-PSK, etc.). The available choice of demodulation will
depend on the FEC type chosen.
(FEC Code Rate) This sub-menu permits the user to select the FEC Code Rate used
for reception (Rate 1/2, Rate 3/4, etc.). The available choice of Code Rate will depend
on both the FEC type and Demodulation selected.
(Data Rate) This sub-menu permits the user to select the receive data rate, in steps of
1 bps. The choice of data rate will depend on the FEC type, Demodulation, and Code
Rate selected.
(Acquisition) This sub-menu permits the user to determine the amount of frequency
uncertainty the demodulator will search over in order to find and lock to an incoming
carrier.
This sub-menu permits the user to control the output state of the transmit carrier.
(Descrambler) This sub-menu permits the user to select whether or not data
descrambling is used.

Buf

(Buffer) This sub-menu permits the user to select whether or not the
Plesiochronous/Doppler buffer is used, and if so, the size of that buffer.

Inv

(Inversion) This sub-menu permits the user to invert the sense of the received
spectrum, or to invert the sense of the received baseband data.

Misc
C-in-C

(Miscellaneous) This sub-menu will allow the user to select Eb/No Alarm Threshold
(EbNo) and Rx roll-off (alpha) factor Rxα.
(Carrier-in-Carrier®) This sub-menu allows the user to set-up the carrier-in-carrier
parameters.

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CDM-Qx Satellite Modem
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IMPORTANT

Revision 5
MN/CDMQx.IOM

The FEC type takes the highest configuration priority, and the selection here
depends on what, if any, optional plug-in Codecs are installed. The choice of
FEC type then determines what demodulation types, code rates, and data rates
are available. The order of hierarchy is therefore:
FEC type ► Demodulation type ► Code Rate ► Data Rate
(Highest)
(Lowest)
If the user changes a parameter within this hierarchy, the other parameters may
become invalid. In this case, the software will change those other parameters, in
order that the configuration remains valid at all times.
Example: Suppose the user has selected Viterbi + Reed-Solomon, QPSK, Rate
1/2. Now, the user changes the demodulation type from QPSK to 16-QAM. In
this case, Rate 1/2 is no longer a valid code rate, and so it will be automatically
changed to the nearest valid code rate (Rate 3/4).
Each of the configuration sub-branches will now be described in detail.

(ConfigRxFEC) – RX FEC TYPE
Rx FEC: Vit Vit+RS TCM+RS
TPC
(◄ ► ENT)

IMPORTANT

All possible choices are presented at all times.
If an option is not installed (either Hardware, or FAST) or valid, the
◄ ► arrow keys will force the cursor to skip past the unavailable
choice.

CASE
Vit (Viterbi)
Vit+R-S (Viterbi +Concatenated
Reed-Solomon)
TCM+R-S (Trellis Coded
Modulation + Concatenated
Reed-Solomon)
TPC (Turbo)

RULES
Always valid
Always valid

COMMENT

If 8-PSK FAST is enabled

Fixed at 8-PSK and
Rate 2/3

If the TPC codec is installed

If Vit, Vit+RS, TCM+RS, or TPC is selected, the following sub-menu will be
displayed:

Rx Rs (n/k):
IESS-310 network

(◄ ►, ENT)
(219/201)

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MN/CDMQx.IOM

(ConfigRxDemod) – DEMODULATION SCHEME
Demodulation: BPSK QPSK 8-PSK
16-QAM
(◄ ► ENT)

IMPORTANT

All possible choices are presented at all times.
If an option is not installed (either Hardware, or FAST) or valid, the
◄ ► arrow keys will force the cursor to skip past the unavailable choice.

CASE
BPSK
QPSK
8-PSK
16-QAM

RULES
Valid for all FEC types except TCM+R-S
Valid for all FEC types except TCM+R-S
Valid for TCM+R-S, TPC (Turbo) requires 8-PSK FAST option
Valid for Viterbi + R-S, TPC (Turbo) requires 16-QAM FAST option

(ConfigRxCode) – RX CODE RATE
Rx Code Rate: 5/16 21/44 1/2
2/3 3/4 7/8 17/18
(◄ ►)

IMPORTANT

CASE
5/16
21/44
1/2
2/3
3/4
7/8
17/18

All possible choices are presented at all times. If an option is not installed
(either Hardware, or FAST) or valid, the ◄ ► arrow keys will force the cursor
to skip past the unavailable choice.
RULES
Valid for BPSK and Turbo
Valid for BPSK, QPSK and Turbo
Valid for BPSK, QPSK, Viterbi, Viterbi+R-S
Valid for TCM+R-S only (8-PSK)
Valid for QPSK, 8-PSK, and 16-QAM
Valid for QPSK, 8-PSK, and 16-QAM
Valid for QPSK, 8-PSK , and Turbo

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(ConfigRxData) – RX DATA RATE
Rx Data Rate: 05000.000kbps
Sym:02500.000ksps
In QDI mode, these data rates are read-only! The data rate will be the sum of the
tributary rates for all ports. This will also show the calculated symbol rate and Nx64kbps
(where N=001 to 124).

IMPORTANT

The overall range of data rates is from 32 to 20000 kbps. The overall range of
symbol rates is up to 10000 ksps. The minimum and maximum data rates are
dependent on modulation type and FEC encoder rate. If the user changes the
modulation or FEC, and the currently selected data rate can no longer be
supported, the data rate will be adjusted automatically, up or down, keeping
the symbol rate constant. The bottom line of the display shows the symbol rate,
based on FEC type, modulation, FEC Code Rate, and Data Rate.

FEC Type
Viterbi

Modulation

Code Rate

BPSK

Rate 1/2

Data Rate Range

Viterbi

QPSK

Rate 1/2

32 kbps to 10 Mbps

Yes – see note below

Viterbi

QPSK

Rate 3/4

32 kbps to 15 Mbps

Yes – see note below

Viterbi

QPSK

Rate 7/8

32 kbps to 17.5 Mbps

Yes – see note below

Viterbi + R-S

BPSK

Rate 1/2

32 kbps to 4.5 Mbps

Yes – see note below

Viterbi + R-S

QPSK

Rate 1/2

32 kbps to 9.1 Mbps

Yes – see note below

Viterbi + R-S

QPSK

Rate 3/4

32 kbps to 13.7 Mbps

Yes – see note below

Viterbi + R-S

QPSK

Rate 7/8

32 kbps to 16 Mbps

Yes – see note below

Viterbi + R-S

16-QAM

Rate 3/4

349.1 kbps to 20 Mbps

Yes – see note below

Viterbi + R-S

16-QAM

Rate 7/8

407.3 kbps to 20 Mbps

Yes – see note below

TCM + R-S

8-PSK

Rate 2/3

232.7 kbps to 18.3 Mbps

Yes – see note below

TPC

BPSK

Rate 5/16

32 kbps to 3.1 Mbps

Yes – see note below

TPC

BPSK

Rate 21/44

32 kbps to 4.7 Mbps

Yes – see note below

TPC

QPSK

Rate 21/44

32 kbps to 9.5 Mbps

Yes – see note below

TPC

QPSK

Rate 3/4

32 kbps to 15 Mbps

Yes – see note below

32 kbps to 5 Mbps

EDMAC limited?
Yes – see note below

TPC

QPSK

Rate 7/8

32 kbps to 17.5 Mbps

Yes – see note below

TPC

QPSK

Rate 17/18

32 kbps to 18.888 Mbps

Yes – see note below

TPC

8-PSK

Rate 3/4

288 kbps to 20 Mbps

TPC

8-PSK

Rate 7/8

336 kbps to 20 Mbps

TPC

8-PSK

Rate 17/18

362.7 kbps to 20 Mbps

TPC

16-QAM

Rate 3/4

384 kbps to 20 Mbps

TPC

16-QAM

Rate 7/8

448 kbps to 20 Mbps

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(ConfigRxFreq) – RX FREQUENCY
Rx IF Freq: 1156.3456 MHz
(◄ ►, ▲ ▼,ENT)
Edit the receive frequency. This is accomplished by selecting the digit to be edited, using
the WXarrow keys. The value of the digit is then changed using the STarrow keys. The
user should then press ENT. The range of frequencies depends upon the plug-in module.
The above examples shows the L-Band version of CDM-Qx.
If (using the ODU, LNB menus) the user has selected an LNB LO frequency (other than
zero) and defined whether the mix is high side or low side, the display will be modified
as shown below, to include the calculated Receive RF frequency of the modem/BUC
combination:

Rx IF Freq:1156.3456 MHz
RF=12156.3456 (◄ ► ▲ ▼ ENT)
As the Rx IF frequency is edited the RF frequency will automatically be updated

(ConfigRxAcq) – DEMOD ACQUISITION RANGE
Demod Acquisition Range:
+/- 32 kHz
(▲ ▼ ENT)
Edit the acquisition search range of the demodulator (the value entered here determines
the amount of frequency uncertainty the demodulator will search over in order to find and
lock to an incoming carrier). Editing the value is accomplished by selecting the digit to be
edited, , using the W Xarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT.
The range varies from ± 1 kHz to ± 32 kHz for 70/140 IF, ± 1 kHz to ±(symbol rate/2) up
to ±200 kHz for L-Band. For symbol rates < 64 ksps, it will be ± (symbol rate/2)
The value entered here determines the amount of frequency uncertainty the demodulator
will search over in order to find and lock to an incoming carrier.

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(ConfigRxDescram) - DESCRAMBLER
Descrambling: Default-On
IESS-315-On Off
(◄ ► ENT)
Options are:
Default-On

the appropriate descrambler type is automatically selected.

IESS-315-On

this only applies when Turbo is installed and has been selected as the FEC
type.

Off

no descrambling.

As before, the options are displayed all of the time, but the ◄ ► arrow keys will force
the cursor to skip past an unavailable choice.
The default descrambler types are:
IMPORTANT

Viterbi, no framing:
Viterbi, EDMAC frame:
Viterbi + RS or TCM/RS:
TPC:

ITU V.35 (Intelsat variant)
Comtech proprietary, frame synchronized
Per IESS-308, frame synchronized
Comtech proprietary, frame synchronized

(ConfigRxBuf) – RX BUFFER CLOCK SOURCE
Rx Buffer: Internal Rx-Sat
Tx-Terrestrial Ins (◄ ►, ENT)
User will select which Rx buffer clock source. Note that Tx-Terrestrial will only be
selected if the cards are grouped as modem. Also, note that External will only be
selected if QDI interface type is selected. Selecting either one will allow the user to select
th e buffer size as shown below:

Rx Buffer Size:
Disabled
(▲ ▼, ENT)
Edit the size, in bits, of the Plesiochronous/Doppler Buffer. The value is changed using
the S T arrow keys. The user should then press ENT. Values of Disabled, ± 512, 1024,
2048, 4096, 8192, and 16384 bits are possible.
When Disabled is selected, the Plesiochronous/Doppler buffer is disabled. The receive
clock will then be derived from the satellite signal, and will therefore be subject to clock
offsets relative to the local transmit clock, This is due in part to the originating clock
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being slightly different from the local clock (a so-called plesiochronous offset), and to
the motion of the satellite (a Doppler offset). The input to the buffer will be the signal
from the satellite, with any clock offsets and jitter. The output from the buffer will be
derived from the local TRANSMIT clock. In this way, the receive data will be perfectly
synchronous with this local clock. The modem operates with independent receive and
transmit data rates. Even in this configuration, where RX data rate <> TX data rate, the
output clock for the buffer will be phase locked to the transmit clock.
While it is only possible to select the size in bits, the corresponding total buffer size is
displayed in ms (which will vary in inverse proportion to the data rate).

(ConfigRxInv) – RX INVERSION FUNCTIONS
Rx Inversion functions:
Spectrum Data Clock (◄ ►, ENT)
Select Spectrum, Data, or Clock using the ◄ ► arrow keys, then press ENT.
If Spectrum is selected, the following sub-menu will be displayed:
Select Normal or Inverted, using the ◄ ► arrow keys, then press ENT.
If Data is selected, the following sub-menu will be displayed:

Rx Data
Sense:
Spectral
Inversion:
Normal Inverted
(◄ ►,
ENT)
►,ENT)
Select Normal or Inverted, using the ◄ ► arrow keys, then press ENT.
If Clock is selected, the following sub-menu will be displayed:

Rx Clock Inversion:
Normal Inverted

(◄ ►, ENT)

Select Normal or Inverted, using the ◄ ► arrow keys, then press ENT.

(ConfigRxMisc) – Rx Miscellaneous
Rx Misc: EbNo Rxα
(◄ ►, ENT)
Select EbNo or Rxα using the WXarrow keys, then press ENT.

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(ConfigRxMiscEbNo) - Eb/No ALARM
Eb/No Alarm Point:
02.0 dB
(◄ ►,▲ ▼,ENT)
Edit the Eb/No alarm point. This is accomplished by selecting the digit to be edited, using
the ◄ ► arrow keys. The value of the digit is then changed using the STarrow keys.
The user should then press ENT.
The range of values is from 2.0 to 16.0 dB. The user may select a value here, and if the
Eb/No falls below this value, a receive traffic fault will be generated.

(ConfigRxMiscRxα) – RX Roll-Off (α) factor
Rx Roll-off: 20%

35%
(◄ ►, ENT)

Select 20% or 35%, using the ◄ ► arrow keys, then press ENT. The default is 35%.

(ConfigRxCnC) – CARRIER-IN-CARRIER®
Carrier-in-Carrier (CnC):
Mode FrqOffs SrchDelay ReAcq
Select Mode, FrqOffs, SrchDelay, or ReAcq using the WXarrow keys, then press
ENT. The user will then be taken to a further sub-menu. Each of these choices is
described briefly in the table below:
Mode

(Mode of Operation) This sub-menu permits the user to select the mode of
operation for the CnC™.

FrqOffs

(Frequency Offset) This sub-menu permits the user to adjust the frequency
offset for the CnC™.

SrchDelay
ReAcq

(Search Delay) This sub-menu permits the user to configure the search
delay parameters for the CnC™.
(ReAcquisition Time) This permits the user to set the re-acquisition time in
seconds when the desired carrier is lost.

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(ConfigRxCnCMode) – CnC® MODE OF OPERATION
CnC Mode: Off On
(◄ ►, ENT)
Select Off, or On using the WXarrow keys, then press ENT. The user will then be
taken to a further sub-menu. If CnC On is selected, there will be some messages at the
front panel as shown below:

LOADING CnC SAT SEARCH...
...PLEASE WAIT!
CnC SEARCH IS PROCESSING...
...PLEASE WAIT!
If CnC is successful, it will display as follows:

CnC SEARCH SUCCESSFUL!
Delay=239ms
Offset=+001.0k
If CnC is not successful, it will display this:

CnC SEARCH IS UNRESOLVED!
PLEASE CHECK TX POWER LEVEL

(ConfigRxCnCFrqOffs) – CnC FREQUENCY OFFSET
CnC Frequency Offset:
+/-015
(▲ ▼ ENT)
Edit the CnC Frequency Offset. The value of the digit is changed using the STarrow
keys. The user should then press ENT.

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(ConfigRxCnCSrchDelay) – CnC SEARCH DELAY
CnC Min/Max Delay (ms):
Min=000 Max=290 (◄ ►,▲ ▼,ENT)
Edit the Min/Max Search Delay in milliseconds by selecting the digit to be edited, using
the WXarrow keys. The value of the digit is then changed using the STarrow keys. The
user should then press ENT.

(ConfigRxCnCReAcq) – CnC RE-ACQUISITION TIME
CnC Re-Acquisition Time:
120 seconds (◄ ►,▲ ▼,ENT)
Edit the re-acquisition time using the WXSTarrow keys. The user should then press
ENT.

5.6.1.4

(ConfigGroup) – GROUPING MOD/DEMOD CARDS
If Group is selected:

Grouping:
Modem
Redundancy

(◄ ►, ENT)

Enter Modem to group a vertically aligned modulator and demodulator into a modem.
The Device Selection screen should indicate either one of the devices that is to be
grouped.
Enter Redundancy to designate the backup for a redundant group. The Device Selection
screen should indicate the device to become the backup.

(ConfigGroupModem)
Modem Group:
Separate
Grouped

(◄ ►, ENT)

If there is a vertically aligned modulator demodulator pair with the modulator in the top
position, then the Modem selection is allowed. The selection applies to the pair of which
one is currently selected in the device select area.
Once grouped, the modulator demodulator pair can be configured as a single device.
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(ConfigGroupRedundancy)
Redundancy: Config Mode
(◄ ►, ENT)
Selecting “Config” allows the user to set redundancy either 1:1, 1:2, 1:3, or none.
Redundancy is a FAST option and needs to be purchased to turn on this feature. Selecting
“Mode” allows the unit to do auto or manual switching between prime and back-up
device.

(ConfigGroupRedundancyConfig)
Config Redundancy:
None 1:1 1:2 1:3

(◄ ►,ENT)

If None is selected, it turns off redundancy.

(ConfigGroupRedundancyConfig 1:1)
Selecting the 1:1 entry configures 1:1 redundant modem. Modulators are required in the
top two slots, and demodulators in the bottom two. Without the proper hardware and
FAST option enabled, the WXarrow keys will force the cursor to skip past the
unavailable choice. The backup modem is installed in slot #3 and slot #4. The user can
also do 1:1 Tx or 1:1 Rx. For ungrouped scenario, the backup card is always installed in
slot #4.

(ConfigGroupRedundancyConfig 1:2)
For 1:2 case, the backup is always installed in slot #4. This is only applicable for
ungrouped scenario (no modem), that means, 1:2 Tx or 1:2 Rx.

(ConfigGroupRedundancyConfig 1:3)
For 1:3 case, the backup is always installed in slot #4. This is only applicable for
ungrouped scenario (no modem), that means, 1:3 Tx or 1:3 Rx.

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(ConfigGroupRedundancyMode)
Redundancy Mode:
Manual Auto

(◄ ►,ENT)

Default is “Manual”. If “Auto” is selected, that means the back-up will automatically
take over once the designated prime is faulted, and vice-versa. If “Manual” is selected,
when the prime is faulted, the back up will not take over. Also, the user will have the
option to do force switching.

(ConfigGroupRedundancyModeManual)
Redundancy Manual Mode:
Forced-Backup = Slot#1 (▲▼,ENT)
If redundancy is configured (e.g. 1:1), force-backup menu will appear which will allow
the user to do force switching between back up and designated primary device.

5.6.1.5

(ConfigFrame) – FRAMING MODE
Framing Mode: Unframed EDMAC
EDMAC-2 D&I++
(◄ ►,ENT)
Framing requires a modulator/demodulator pair grouped into a modem (see
ConfigGroup).
Select Unframed, EDMAC, EDMAC-2, or D&I++ using the ◄ ► arrow keys, then
press ENT.
The sub-branches available are:

(ConfigFrameUnframed) - UNFRAMED
No framing is selected. No overhead is added, and the unit will be compatible with other
manufacturer’s equipment, when operating in a ‘standard’ configuration.

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(ConfigFrameEDMAC, or ConfigFrameEDMAC-2) EDMAC or EDMAC-2
Comtech EF Data proprietary framing is included. The framing permits the bi-directional
passing of M&C and AUPC data between local and distant-end units. EDMAC is
backwards compatible with the CDM-500, CDM-550, CDM-550T, CDM-600 and
CDM-600L. EDMAC-2 is a reduced overhead version of EDMAC, and is not backwards
compatible with the modems listed above.
If either of these modes is selected, the following sub-menu will be displayed:

Framing mix:
AUPC+EDMAC

AUPC-Only
(◄ ►,

Select either AUPC-Only (default) or AUPC+EDMAC, using the ◄ ► arrow keys,
then press ENT.
Note that if framing is enabled (either EDMAC or EDMAC-2), then AUPC is
automatically enabled, but the specific EDMAC feature (passing M&C data from a local
to a distant-end unit) needs to enabled here.
If AUPC-Only is selected then none of the EDMAC features are available, even though
framing will still be enabled.
If AUPC+EDMAC is selected, the user is further prompted to select whether the unit is
an EDMAC master, or an EDMAC slave:

(ConfigFrameEDMACAUPC+EDMAC, or
ConfigFrameEDMAC-2AUPC+EDMAC) AUPC+EDMAC MODE
EDMAC Mode:
Master Slave

(◄ ►, ENT)

Select either MASTER or SLAVE, using the ◄ ► arrow keys, then press ENT.
An EDMAC MASTER is a unit which is local to the M&C computer, and which passes
messages, via the overhead, to a distant-end modem.
An EDMAC SLAVE is a unit that is not local to the M&C computer, which is at the
distant-end of a satellite link. If MASTER is selected then the following sub-menu is
displayed:

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Distant-end Base Address
0240
(◄ ►,▲ ▼, ENT)
Edit the address of the distant-end modem that this unit will pass messages to. This is
accomplished by selecting the digit to be edited, using the ◄ ► arrow keys. The value of
the digit is then changed using the STarrow keys. The user should then press ENT.
There is a restriction on values that can be entered here - they may only be in increments
of 10. This is automatically taken care of - the user may not edit the last digit of the
address. This has been implemented so that a single MASTER may pass messages for up
to 10 devices at the distant end. The valid range of addresses is from 10 to 9990.
But if SLAVE is selected, then the following sub-menu is displayed:

Address of this Slave
Unit: 0241
(◄ ►,▲ ▼,ENT)
Edit the address of this SLAVE unit. This is accomplished by selecting the digit to be
edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The valid range of addresses is from 1
to 9999, although ‘base 10' values will be automatically skipped.

IMPORTANT

Remember that this is a unit that is intended to be located at the distant-end of
a link, and will therefore be under the control of a MASTER at the other
end. This is the equivalent of putting the unit into Remote Control mode no local control is possible.

(ConfigFrameD&I++) – D&I++
If D&I++ is selected, the following sub-menu will be displayed:

Drop & Insert: EDMAC
Drp-CH/TS Ins-CH/TS (◄ ►, ENT)
If Drp-CH/TS is selected, the Tx Data Rata will be displayed.
If the Ins-CH/TS is selected the Rx data rate will be displayed.

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(ConfigInterface) – DATA INTERFACE
Data interface for each card (modulator or demodulator) is auto detected. If grouped as a
modem, the operating data interface will be the one installed in the demod card (interface
on the modulator is not required). If a QDI interface is installed and a modem is grouped,
then either it or the interface installed on the Demod can be selected. The card can
support one of the following:
•
•
•
•
•
•

RS-422 (RS-530)
V.35
RS-232
G.703 (for single T1 or E1)
HSSI
QDI (Quad Drop & Insert)

The blinking cursor will point to the supported data interface for the card being installed,
then press ENT

Interface: RS422 V.35 RS232
HSSI ASI G.703 QDI NONE
If grouped as a modem and RS422, V.35 or RS232 are selected, the following sub menu
will be displayed:

RTS/CTS operation: (▲ ▼, ENT)
Loop,RTS Controls Tx Out
The option is changed using the STarrow keys. The user should then press ENT. The
following options are possible:
RTS/CTS Loop, No Action

RTS and CTS are looped, so that CTS echoes the state of RTS,
but RTS does not control the ON/OFF state of the carrier.

Loop, RTS Controls Tx Out

RTS and CTS are looped, so that CTS echoes the state of RTS,
and RTS controls the ON/OFF state of the carrier (in other
words, the modem will not bring up its TX carrier until RTS is
asserted.

Ignore RTS, Assert CTS

RTS is ignored, and CTS is asserted unconditionally.

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If HSSI is selected, the following sub menu will be displayed:

HSSI Mode Select:
TA to CA Loop

(▲ ▼, ENT)

The option is changed using the STarrow keys. The user should then press ENT. The
following options are possible:
TA to CA Loop

TA and CA are looped, but TA does not control the ON/OFF
state of the carrier.

RR controls CA, TA controls
Tx Out

TA controls the ON/OFF state of the carrier (in other words, the
modem will not bring up its TX carrier until TA is asserted.

If G.703 is selected, the following sub menu will be displayed:

G.703 Type: T1 E1-Balanced
E1-Unbalanced
(◄ ►,
If G.703 balanced interface, the user can select either T1 or E1-Balanced. If G.703
unbalanced interface, the user can select either T1 or E1-Unbalanced. Use the ◄ ►
arrow keys to select, then press ENT.
If T1 is selected, the following sub-menu will be displayed:

T1 Configuration:
Length Line-Code

(◄ ►, ENT)

Select Length or Line Code using the ◄ ► arrow keys, then press ENT.
If Line –Code is selected, the following sub-menu will be displayed:

G.703 T1 Line Code:
HDB3 AMI
(◄ ►, ENT)
Select HDB3 or AMI using the ◄ ► arrow keys, then press ENT.

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If Length is selected, the following sub-menu will be displayed:

T1 Line Length:
000-133 feet
ENT)

(▲ ▼,

Edit the line length using the STarrow keys, then press ENT Values will toggle
between the following values:
0-133, 133-266, 266-399, 399-533, and 533-655 feet.
If either E1-Balanced or E1-Unbalanced is selected, the following sub-menu will be
displayed:
Select HDB3 or AMI using the W Xarrow keys, then press ENT.

G.703 E1 Line Code:
HDB3
AMI
(◄ ►, ENT)
If QDI is selected, the following sub-menu will be displayed:
QDI Tributary Ports:
1 2 3 4
(◄ ►, ENT)
In this sub menu, the user can select one of the four (4) ports to be configured. Choosing
either one of them will display the next sub-menu as follows:
Port#X: Drop Insert LineCode
Alarm
(◄ ►, ENT)
Where X is the tributary port number. If Drop is selected, the next sub-menu will be
Port#X Tx Trib Rate:(▲▼, ENT)
01536.000kbps
(24x64kbps)
This sub-menu shows the Nx64kbps data rate where N=24 in this example. Use
STarrow keys to set the data rate. After pressing ENT, a sub-menu will appear as
shown:
Px D-CH: 1 2 3 4 5 6 ►
TS: 11 02 06 04 05 03
Where x is the tributary port number. A X display means that there are more channels
beyond channel 6 as in this example. Use right arrow key X to view more. sure that ENT
key is pressed once it’s done.

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If Insert is selected, the sub-menu will display:
Port#X Rx Trib Rate:(▲▼, ENT)
01536.000kbps
(24x64kbps)
IMPORTANT

This is similar to the drop-side. Upon setting the data rate, a sub-menu will appear as
shown:
Px I-CH: 1 2 3 4 5 6 ►
TS: 11 02 06 04 05 03
This is similar to the drop-side except that this is done at the Rx side. Please make sure
that ENT key is pressed once it’s done.
If LineCode is selected, the next sub-menu will be displayed:
Port#X Line Code:
HDB3 AMI

(◄ ►, ENT)

Select HDB3 or AMI using the W Xarrow keys, then press ENT.
If Alarm is selected, the sub-menu will display
Port#X Bipolar Violation:
Active Masked
(◄ ►, ENT)
Default is Masked.

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(ConfigRef) - REFERENCE OSCILLATOR
The modem can accept an externally supplied frequency reference, using the BNC
connector on the rear panel. However, rather than bypassing the internal reference, and
substituting the external signal, the internal reference is used in a low-bandwidth (~ 2Hz)
phase-locked loop (PLL), so the modem actually phase locks to the reference external
signal. There are two distinct advantages to this scheme:
a. It permits hitless switching between the operation of internal and external reference.
There are no sudden discontinuities of frequency and phase in the transmitted carrier.
b. Due to the very low bandwidth of the PLL, it permits the external reference to have
an inferior phase noise characteristic than the internal reference of the modem. The
narrow loop essentially ‘cleans up’ the external signal. This is particularly important
if the modem is being used to supply a 10MHz reference to a BUC or LNB.
Edit the configuration and value of the frequency reference. The value is changed using
the STarrow keys. The user should then press ENT. Values of Internal 10 MHz,
External 01 MHz, External 02 MHz, External 05 MHz, External 10 MHz, External
20 MHz, Out Int. 10 MHz, and Auto are possible.
The user should then press ENT. Two examples are shown below:

Frequency Reference:
Internal 10 MHz
(▲ ▼, ENT)
Frequency Reference:
External 05 MHz
(▲ ▼, ENT)

5.6.1.8

(ConfigMask) - MASK
Select Transmit, Receive or Reference, using the ◄ ► arrow keys, then press ENT.

Alarm Mask: Transmit Receive
Reference BUC LNB (◄ ►,ENT)

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If Transmit is selected the following sub-menu will be displayed:

Tx Alarm Mask: Tx-FIFO
G.703-BPV Tx-AIS
(◄ ► ENT)
Select Tx-FIFO, G.703-BPV, or Tx-AIS, using the ◄ ► arrow keys, then press ENT.
For each of the choices a sub-menu similar to the one shown below will be shown:

Tx-FIFO Alarm:
Active Masked

(◄ ► ENT)

Select Active or Masked, using the ◄ ► arrow keys, then press ENT.
If the user selects Active, then a Transmit Traffic fault will be generated whenever the
transmitter sees that the transmit FIFO has slipped.
Similarly, the user can mask a G.703 BPV or Transmit AIS alarm.
If the user selects Masked, no alarm will be generated.
If Receive is selected the following sub-menu will be displayed:

Rx Alarm Mask: AGC Eb/No
Rx-AIS Buffer
(◄ ► ENT)
Select AGC, Eb/No, Rx-AIS or Buffer, using the ◄ ► arrow keys, then press ENT. For
each of the choices a sub-menu similar to the one shown below will be shown:

AGC Alarm:
Active Masked

(◄ ► ENT)

Select Active or Masked, using the ◄ ► arrow keys, then press ENT.
If the user selects Active, then a Receive Traffic fault will be generated whenever the
demodulator sees that the composite input level being applied will cause compression in
the IF stages, and hence degrade the performance of the demodulator.
Similarly, the user can mask an Eb/No, Receive AIS or Buffer alarm.
If the user selects Masked, no alarm will be generated.

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If Reference is selected the following sub-menu will be displayed:

Reference Alarm:
Active Masked

(◄ ► ENT)

Select Active or Masked, using the ◄ ► arrow keys, then press ENT.
If the user selects Active, then a unit fault will be generated whenever the unit sees:
1. External Reference is selected
2. There is no signal activity at the external reference port
If the user selects Masked, no alarm will be generated.
If BUC is selected the following sub-menu will be displayed:

BUC Alarm:
Active Masked

(◄ ► ENT)

Select Active or Masked, using the ◄ ► arrow keys, then press ENT.
If LNB is selected the following sub-menu will be displayed:

LNB Alarm:
Active Masked

(◄ ► ENT)

Select Active or Masked, using the ◄ ► arrow keys, then press ENT.

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(ConfigODU) – OUTDOOR UNIT (for L-Band Unit Only)
ODU (Outdoor Unit):
BUC LNB
(◄ ► ENT)
The ODU (Outdoor Unit) menu permits the user to choose between controlling and
monitoring either a BUC (Block Upconverter) or an LNB (Low-noise Block
downconverter). Select BUC or LNB, using the ◄ ► arrow keys, then press ENT.

(ConfigODUBUC) – BLOCK UPCONVERTER (BUC)
If BUC is selected, the following sub-menu is displayed:

BUC:M&C-FSK DC-Pwr 10MHz
Alarm Delay LO Mix(◄ ► ENT)
Select M&C-FSK, DC-Pwr, 10MHz, Alarm, Delay, LO, or Mix, using the ◄ ► arrow
keys, then press ENT.
M&C-FSK

If an FSK-capable BUC is employed, this menu provides access to
a further set of menus that define the FSK setup, and use it for
control and monitor.

DC-Pwr

(DC POWER) If a BUC supply is installed this menu permits the
user to turn DC power ON or OFF.

10MHz

This menu permits the user to turn the 10MHz frequency reference
for the BUC ON or OFF.

Alarm

This menu permits the user to define the upper and lower limits for
a current ‘window’. If the measured BUC current falls outside this
window, an alarm is generated.

Delay

This menu permits the user to define the carrier-on delay following
a power-up sequence.

This menu permits the user to define the LO frequency used in the
BUC. This is then used in the display of RF frequency in the
ConfigTxFreq menu.

Mix

This menu permits the user to define the sense of the frequency
translation – either high-side mix or low-side mix.

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(ConfigODUBUCM&C-FSK) - M&C FSK
If M&C-FSK is selected, the following sub-menu is displayed:

BUC M&C-FSK: Comms Address
Tx-On/Off
(◄ ►, ENT)
Select Comms, Address, Tx-On/Off, or Pwr-Level, using the ◄ ► arrow keys, then
press ENT.
Comms

If an FSK-capable BUC is employed, this menu turns the FSK
between the modem and BUC either ON or OFF.

Address

(Address) This menu permits the user to enter the logical
address of the BUC, from 1 to 15.

TX-On/Off

This menu permits the user to turn the RF Output of the BUC
ON or OFF.

(ConfigODUBUCM&C-FSKAddress) – FSK COMMS
If Comms is selected, the following sub-menu is displayed:

BUC M&C FSK Comms:
On Off

(◄ ►, ENT)

Select On or Off, using the ◄ ► arrow keys, then press ENT.

(ConfigODUBUCM&C-FSKAddress) – FSK ADDRESS
If Addr is selected, the following sub-menu is displayed:

BUC FSK Address: 01

(▲▼, ENT)

Edit the value of the address using the ▲ ▼ arrow keys, then press ENT. The valid range
is from 01 to 15.

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(ConfigODUBUCM&C-FSKTx-On/Off) - FSK TX-ON/OFF
If Tx-On/Off is selected, the following sub-menu is displayed:

BUC RF Output:
On Off

(◄ ►,ENT)

Select On or Off, using the ◄ ► arrow keys, then press ENT.

(ConfigODUBUCDC-Pwr) - BUC DC POWER
If DC-Pwr is selected, the following sub-menu is displayed:

BUC DC Power:
On Off

(◄ ►,ENT)

Select On or Off, using the ◄ ► arrow keys, then press ENT.

(ConfigODUBUC10MHz) – BUC 10MHz
If 10MHz is selected, the following sub-menu is displayed:

BUC 10MHz Reference:
On Off
(◄ ►, ENT)
Select On or Off, using the ◄ ► arrow keys, then press ENT.

(ConfigODUBUCAlarm) - BUC ALARM
If Alarm is selected, the following sub-menu is displayed:

Set BUC Current Alarm:
Upper Lower
(◄ ►, ENT)
Select Upper or Lower, using the ◄ ► arrow keys, then press ENT.

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If Upper is selected, the following sub-menu is displayed:

BUC Current Alarm Upper
Limit:1200mA
(◄ ►,▲▼, ENT)
Edit the BUC Current Alarm Upper limit. This is accomplished by selecting the digit to
be edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The range of current is from 500 to
4000 mA.
If Lower is selected, the following sub-menu is displayed:

BUC Current Alarm Lower
Limit:1200mA
(◄ ►,▲▼, ENT)
Edit the BUC Current Alarm Lower limit. This is accomplished by selecting the digit to
be edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The range of current is from 100 to
3000 mA.

(ConfigODUBUCDelay) - BUC DELAY
If Delay is selected, the following sub-menu is displayed:

BUC Power-On Delay:
001 seconds
(◄ ►▲ ▼ ENT)
Edit the value of the power-on delay. This is accomplished by selecting the digit to be
edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The valid range is from 0 to 999
seconds.

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(ConfigODUBUCLO) - BUC LO
If LO is selected, the following sub-menu is displayed:

BUC LO Frequency:
12000 MHz
(◄ ► ▲ ▼ ENT)
Edit the value of the BUC LO frequency. This is accomplished by selecting the digit to
be edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The valid range is from 0 to 35000
MHz.
Note that this value is used for displaying the RF frequency of the modem/BUC
combination. If a value of 00000 is entered here (the default) then no RF frequency will
be displayed on the ConfigTxFreq menu.

(ConfigODUBUCMix) – BUC MIX
If Mix is selected, the following sub-menu is displayed:

BUC Frequency Mix:
High-Side Low-Side

(◄ ► ENT)

Select High-Side or Low-Side, using the ◄ ► arrow keys, then press ENT.

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(ConfigODULNB) LNB
If LNB is selected, the following sub-menu is displayed:

LNB: DC-Voltage
LO Mix

10MHz Alarm
(◄ ►, ENT)

Select Voltage, Power-On/Off, 10MHz, Alarm, LO or Mix, using the ◄ ► arrow
keys, then press ENT.
Voltage

Selects 13 or 18 Volts as the LNB power supply output voltage.

10MHz

This menu permits the user to turn the 10MHz frequency reference
for the BUC ON or OFF.

Alarm

This menu permits the user to define the upper and lower limits for
a current ‘window’. If the measured LNB current falls outside this
window, an alarm is generated.

This menu permits the user to define the LO frequency used in the
LNB. This is then used in the display of RF frequency in the
ConfigRxFreq menu.

Mix

This menu permits the user to define the sense of the frequency
translation – either high-side mix or low-side mix.

(ConfigODULNBVoltage) - LNB VOLTAGE
If Voltage is selected, the following sub-menu is displayed:

LNB DC Supply Voltage:
Power Off
(▲▼, ENT)

Edit the value of the LNB supply voltage, using the STarrow keys. The user should
then press ENT. The choices are 13 or 18 Volts.

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(ConfigODULNBPower-On/Off) – LNB POWER- ON/OFF
If Power-On/Off is selected, the following sub-menu is displayed:

LNB Power:
On Off

(◄ ► ENT)

Select On or Off, using the ◄ ► arrow keys, then press ENT.

(ConfigODULNB10MHz) - LNB 10MHz
If 10MHz is selected, the following sub-menu is displayed:

LNB 10MHz Reference:
On Off
(◄ ► ENT)
Select On or Off, using the ◄ ► arrow keys, then press ENT.

(ConfigODULNBAlarm) - LNB ALARM
If Alarm is selected, the following sub-menu is displayed:

Set LNB Current Alarm:
Upper Lower
(◄ ► ENT)
Select Upper or Lower, using the ◄ ► arrow keys, then press ENT.
If Upper is selected, the following sub-menu is displayed:

LNB Current Alarm Upper
Limit: 200mA
(◄ ► ▲ ▼ ENT)
Edit the LNB Current Alarm Upper limit. This is accomplished by selecting the digit to
be edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The range of current is from 50 to 600
mA.

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If Lower is selected, the following sub-menu is displayed:

LNB Current Alarm Lower
Limit: 050mA
(◄ ►▲ ▼ ENT)
Edit the LNB Current Alarm Lower limit. This is accomplished by selecting the digit to
be edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The range of current is from
10 to 400 mA.

(ConfigODULNBLO) LO
If LO is selected, the following sub-menu is displayed:

LNB LO Frequency:
12000 MHz
(◄ ►▲ ▼ ENT)
Edit the value of the LNB LO frequency. This is accomplished by selecting the digit to be
edited, using the WXarrow keys. The value of the digit is then changed using the
STarrow keys. The user should then press ENT. The valid range is from 0 to 35000
MHz.
Note that this value is used for displaying the RF frequency of the modem/BUC
combination. If a value of 00000 is entered here (the default) then no RF frequency will
be displayed on the ConfigRxFreq menu.

(ConfigODULNBMix) MIX
If Mix is selected, the following sub-menu is displayed:

LNB Frequency Mix:
High-Side Low-Side

(◄ ► ENT)

Select High-Side or Low-Side, using the ◄ ► arrow keys, then press ENT.

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MONITOR
MONITOR: Alarms
Rx-Params
Event-Log Stats AUPC CnC ODU
Select Alarms, Rx-Params, Event-Log, Stats, AUPC, CnC or ODU using the
◄ ► arrow keys, then press ENT. The ODU menu will only appear for 70/140MHz
units.
If the user selects Alarms, the following sub-menu is displayed:

5.6.2.1

(MonitorAlarms) ALARMS

IMPORTANT

The modem uses a system of Fault Prioritization. In each category of fault,
only the highest priority fault is displayed. For instance, if the demodulator is
unlocked, it is irrelevant if there are other receive faults present. If the
demodulator then locks, but there is a fault of a lower priority present, this will
then be displayed. This also holds true for the faults reported via the remote
control. This system cuts down drastically on unwanted and irrelevant fault
reporting. A comprehensive list of faults is shown at the end of this section.

Live Alarms: Transmit
Receive Unit ODU
(◄ ►,ENT)
Select Transmit, Receive, or Unit using the WXarrow keys, then press ENT. Depending
on the choice , one of the following menus will be shown:

(MonitorAlarmsUnit) – UNIT ALARMS
Unit Fault: -12 Volt PSU
is under voltage
(ENT)
The screen will indicate if there are any Unit Faults. If not, it will display ‘None’.
Pressing ENT takes the user back to the previous menu.

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(MonitorAlarmsReceive) – RECEIVE ALARMS
Rx Traffic: AGC Alarm Reduce Input level

(ENT)

The screen will indicate if there are any Receive Traffic Faults. If not, it will display
‘None’. Pressing ENT takes the user back to the previous menu.

(MonitorAlarmsTransmit) - TRANSMIT ALARMS
Tx Traffic: No Tx
From Terrestrial

Clock

(ENT)

The screen will indicate if there are any Transmit Traffic Faults. If not, it will display
‘None’. Pressing ENT takes the user back to the previous menu.

(MonitorAlarmsODU) – OUTDOOR UNIT ALARMS
The screen will indicate if there are any ODU Alarms. If not, it will display ‘None’.
Pressing ENT takes the user back to the previous menu.

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(MonitorRx-Params) – RECEIVE-PARAMETERS
If the user selects Rx-Params, the following sub-menu is displayed:

EbNo=05.7dB
BER=3.4E-9
UF=+11.7k Buf=50% RSL=-24dBm
If the demodulator is locked, this screen shows the following:
Eb/No

This shows the value of Eb/No calculated by the demodulator. The
value referred to here is the energy per information bit (Ebi), divided
by the noise spectral density (No).

BER

This is an estimate of the corrected BER.

The frequency offset of the received carrier, in kHz, with a displayed
resolution of 100 Hz.

Buf

(Buffer fill state) This shows the fill state (in percent), of the receive
Buffer. After a reset, it will read 50. A value <50 indicates that the
buffer is emptying, and >50 indicates that it is filling.

RSL

(Receive Signal Level) A value in dBm, indicating the input power of
the desired carrier, as seen by the demodulator. If the signal level is
below the AGC range of the demod, this will display RSL <-99

If the demodulator is not locked, this screen shows the message ‘‘Demod: Not
Locked’, but continuing to display receive signal level the Pressing ENT or
CLR will take the user back to the previous menu.

Demodulator: Not Locked
UF=+11.7k
RSL=-24dBm

5.6.2.3

(MonitorEvent-Log) – EVENT-LOG or STORED EVENTS
If the user selects Event-Log, the following sub-menu is displayed:

Stored Events:
View Clear-All

(◄ ►,ENT)

Select View or Clear-All, using the ◄ ► arrow keys, then press ENT.
If the user selects View, the following screen is displayed:

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Log 023: 30/11/02 10:37:32
Fault - Demod Lock (3) (▲▼,ENT)
In this example, the demodulator installed in slot #3 is faulted on Nov. 30, 2002 at
10:37:32 with log number 23.

(MonitorEvent-LogView) – VIEW STORED EVENTS
The user may scroll backwards or forwards through the entries in the event log, using the
STarrow keys. Pressing ENT or CLR will take the user back to the previous menu. The
event log can store up to 255 events. When a fault condition occurs, it is time-stamped and
put into the log. Similarly, when the fault condition clears, this is also recorded, as shown
below:

Log 024: 30/11/97 10:37:35
Clear - Demod Lock (3) (▲▼,ENT)
If the user selects Clear-All, the event log is cleared, and the user is taken directly back
to the previous menu. However, if there are faults present on the unit at this time, they
will be re-time-stamped, and new log entries will be generated.

IMPORTANT: Note that in accordance with international convention, the
date is shown in DAY-MONTH-YEAR format.
IMPORTANT

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(MonitorStats) – LINK STATISTICS (for grouped as modem only)
If the user selects Stats, the following sub-menu is displayed:

Link Statistics: View
Clear-All Config
(◄ ►,ENT)
Select View, Clear-All, or Config, using the ◄ ► arrow keys, then press ENT.

(MonitorStatsView) – VIEW LINK STATISTICS
If the user selects VIEW, the following screen is displayed:

Sta198: 02/11/02 10:37:32
16.0, 16.0, 9.0, 9.0 (▲▼,ENT)
The user may scroll backwards or forwards through the entries in the statistics log, using
the STarrow keys. Pressing ENT or CLR will take the user back to the previous menu.
The event log can store up to 250 events.
The top line of the display indicates the log entry number, and the time and date of the
entry. Note that in accordance with international convention, the date is shown in DAYMONTH-YEAR format.
The bottom line of the display shows the statistics data that has been measured and
recorded.
The meaning and format of the numbers is as follows:
Minimum Eb/No, Average Eb/No, Maximum TPLI, Average TPLI
(where TPLI means Transmit Power Level increase, if AUPC is enabled).
The user defines a measurement interval (see MonitorStatsConfig) and during this
interval, Eb/No and TPLI are observed, at a one second rate. At the end of this period, the
average Eb/No is calculated and recorded, and the minimum value seen in the interval.
Similarly, the average TPLI is calculated, along with the highest value seen in the
interval.
Notes: If the demod has lost lock during the measurement interval, the minimum Eb/No
will show ‘Loss’ rather than indicate a value. However, the average value (while the
demod was locked) will still be calculated and shown. If, on the other hand, the
demodulator has been unlocked for the entire measurement interval, the average Eb/No
will also show ‘Loss’. (The display will show ‘Loss, Loss’.)

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If the measured values are greater than, or equal to 16.0 dB, the display will show
16.0 dB. If AUPC is not enabled, the values of maximum and average TPLI will both
show ‘Off'.
Examples:
08.0, 13.5, 2.5, 1.8 means:
Minimum Eb/No observed in the measurement interval = 8.0 dB
Average Eb/No observed in the measurement interval = 13.5 dB
Maximum TPLI observed in the measurement interval = 2.5 dB
Average TPLI observed in the measurement interval = 1.8 dB
Loss, 04.5, Off, Off means:
There was a loss of demod lock during the measurement interval
Average Eb/No observed in the measurement interval = 4.5 dB
Maximum TPLI observed in the measurement interval = AUPC disabled
Average TPLI observed in the measurement interval = AUPC disabled
If the user selects Config, the following sub-menu is displayed:

(MonitorStatsClear-All) – CLEAR ALL STATS
If the user selects Clear-All, the statistics log is cleared, and the user is taken directly
back to the previous menu.

Clear all Stored Stats?
No Yes
(▲▼,ENT)
If the user selects Config, the following sub-menu is displayed:

(MonitorStatsConfig) – CONFIGURE STATS
Stats Logging Interval:
Disabled
(▲▼,ENT)
The user is prompted to enter the logging interval (the period of time over which the
statistics will be measured), using the STarrow keys, then press ENT. The user can
choose Disabled, 10, 20, 30, 40, 50, 60, 70, 80, or 90 minutes.

Stats Logging Interval:
30 minutes
(▲ ▼ ENT)

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(MonitorAUPC) – MONITOR AUPC(for grouped as modem only)
If AUPC is selected, and the modem is not in Framed mode, the following sub-menu is
displayed:

Framing is required for
AUPC Monitor
(ENT or CLR)
If AUPC is selected, and the modem is in Framed mode, the following sub-menu is
displayed:

AUPC:Remote EbNo = 14.0dB
TX Power Increase = 2.2dB
The top line displays the value of Eb/No of the demodulator at the distant end of the
satellite link. The Eb/No will display Unlock if the remote demod is unlocked. The
bottom line shows how much the AUPC system has increased the output power. If AUPC
is not enabled, the value of Tx Power Increase will show as 0.0 dB.

5.6.2.6

(MonitorCnC) – MONITOR CARRIER-IN-CARRIER (CnC™)
(for grouped as modem only)
If CnC is selected, and the CnC is not locked, it will display as follows:

Carrier-in-Carrier (CnC)
is not locked
If CnC is locked, it will display as follows:

CnC:Dly=000,239μs Uf=+001.0k
Eb/No=12.0dB
Ratio=+01dB
Some definitions:
Dly = delay of interferer in microseconds.
Uf = frequency offset of interferer in kHz.
Eb/No = Eb/No estimate in dB
Ratio = interferer-to-desired carrier level ratio in dB

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(MonitorODU) – MONITOR ODU (for L-Band Unit only)
If ODU is selected, the following sub-menu is displayed:

Outdoor Unit Monitor:
ODU LNB
(◄ ►, ENT)

If BUC is selected, the following menu is displayed:

BUC: DC=47.8V,3.2A T=38oC
SW=1.1 PLL=Flt Pwr=02.1W
The menu displays the following parameters:
DC Pwr
T
SW
PLL
Pwr

(DC Power) If a BUC supply is installed, displays
measured BUC supply voltage and load current,
measured at the Tx-IF connector.
(Temperature) If BUC FSK is enabled, displays
BUC ambient temperature in °C.
If BUC FSK is enabled, displays the M&C
software version of the BUC.
If BUC FSK is enabled, displays the fault status of
the BUC PLL synthesizers.
(Output) If BUC FSK is enabled, displays the
output power as measured by the BUC power
monitor.

Press ENT or CLR to return to the next-highest menu.
Select LNB or BUC, using the ◄ ► arrow keys, then press ENT.
If LNB is selected, the following menu is displayed:

LNB Voltage: 13.1 volts
LNB Current: 235 mA
(ENT)
The menu displays the LNB Voltage and Current. Press ENT or CLR to return to the
next-highest menu.

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TEST:
Selecting Test will display this sub-menu:

TEST: Mode BIST
(◄ ►, ENT)
Spec-Analyzer
Select Mode, BIST, or Spec-Analyzer using the ◄ ► arrow keys, then press ENT.
Note that BIST stands for built-in system test. Selecting Mode will display this submenu:

Mode: Norm IF2 Dig2 I/O2 RF2
Tx-CW Tx1-0
(◄ ►, ENT)
All the modes are available if grouped as modem. However, in ungrouped case, for
example Tx, Norm, Tx-CW, and Tx1-0 are the only selection. For Rx only, it is always
in Norm.
Select Norm, IF Loop, Dig Loop, I/O Loop, RF Loop, Tx-CW, or Tx-1,0, using the
◄ ► arrow keys, then press ENT.

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This sub-menu permits the user to select the following test modes:
Norm

IF Loop

Dig Loop

I/O Loop

RF Loop

TX-CW

TX-1,0

(Normal) This clears any test modes or loopbacks, and places the unit back into an
operational state.
(IF Loopback) This test mode invokes an internal IF loop. This is a particularly useful
feature, as it permits the user to perform a quick diagnostic test without having to
disturb external cabling. Furthermore, all of the receive configuration parameters are
temporarily changed to match those of the transmit side. When Normal is again
selected, all of the previous values are restored. During an IF Loop, the Tx carrier
continues to be transmitted. See Figure 5-4.
(Digital Loopback) This test mode invokes a digital Loopback, which loops data at the
output of the framer/scrambler on the transmit side, back into the deframer/descrambler
on the receive side. If concatenated Reed-Solomon FEC is being used, this is also
included in the digital loop. See Figure 5-4.
(Inward/Outward Loopback) This test mode invokes two distinct loopbacks. The first
of these is the inward loop, which takes data being received from the satellite direction,
and passes it directly to the modulator. Simultaneously, the outward loop is invoked,
whereby data being fed to the transmit data interface is routed directly back out of the
receive data interface. See Figure 5-4.
(RF Loopback) This test mode is almost identical to the IF loop mode. All of the
receive configuration parameters are temporarily changed to match those of the
transmit side, however, no internal connection is made. This is useful for performing a
satellite Loopback. When NORMAL is again selected, all of the previous values are
restored.
(Transmit CW) This is a test mode, which forces the modulator to transmit a pure
carrier (unmodulated). Used for measuring phase noise.
(Transmit an alternating 1,0,1,0 pattern) This is a test mode that forces the modulator
to transmit a carrier modulated with an alternating 1,0,1,0 pattern, at the currently
selected symbol rate. This causes two discrete spectral lines to appear, spaced at +/half the symbol rate, about the carrier frequency. This mode is used to check the carrier
suppression of the Modulator. If OQPSK is selected as the modulation type, the test
will produce a spectral pattern suitable for the measurement of SSB rejection – useful in
determining the phase and amplitude accuracy of the modulator.

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If BIST is selected, the display will show:

BIST: BERT-Config
BERT-Control

BERT-Mon
(◄ ►, ENT)

The Built-In System Test (BIST) specifically refers to the built-in BERT (BER Tester). If
BERT-Config is selected:

BERT Config: Tx=ON Rx=ON
Tx-Pat=2047 Rx-Pat=2047
If the selected slot is Tx, the Rx parameters are not selectable, and vice-versa. Note the
BERT generator resides at the Tx side while the BERT monitor resides at the Rx side.
This menu allows to turn ON/OFF either the BERT generator or monitor and selects the
BERT pattern as the user may desire. The BERT pattern supported are Space, Mark, 1:1,
1:3, 63, 511, 2047, 2047R (or 2047 alternate), MIL-188, 2^15-1, 2^20-1, and 2^23-1.
If BERT-Mon is selected:

BERT Monitor: Errs=0000253
BER=8.5E-07
If BERT monitor is turned ON, results are being displayed in bit errors and average BER.
If it displays BER=SyncLoss that means there was a loss of pattern synchronization. If it
displays BER=No Sync, that means pattern synchronization is not achieved. When the
BERT monitor is sync, the BER displays a value (e.g. BER=8.5E-07).
If BERT-Control is selected:

BERT Control: 10E-3Err=OFF
Restart=NO SyncThres=>256
The 10E-3Err control resides at the Tx. This generates an average BER=1.0E-03 once
monitored at the Rx side. The Restart control is to reset the BERT monitor (Rx side) for
a fresh start of BER measurement. The SyncThres control is the synchronization loss
threshold as defined:
a.
b.
c.
d.

>256 = 256 bit errors counted in less than 1000 bits o data
low = 100 bit errors in less than 1000 bits of data
med = 250 bit errors in less than 1000 bits of data
high = 20,000 bit errors in less than 100,000 bits of data

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If Spec-Analyzer is selected:

Spectrum Analyzer:
Mode Config

(◄ ►, ENT)

Selecting Mode will display:

Spectrum Analyzer Mode:
Off On
(◄ ►, ENT)
This menu allows the user to turn ON or OFF the engine of the spectrum analyzer. If
spectrum analyzer mode is ON, the user can use Comtech’s application software
(Windows) to view the spectrum, or use the Web browser.
Selecting Config will display:

Config Spectrum Analyzer:
CenterFreq Span
(◄ ►, ENT)
If CenterFreq is selected:

Spectrum Analyzer: (◄ ►,▲▼,ENT)
Center Freq = 0070.0000 MHz
The Center Freq is similar to Rx Frequency in a regular demodulation function with a
resolution of 100 Hz.
If Span is selected:

Spectrum Analyzer:
Span = 12.5 MHz

(▲▼,ENT)

The user can only select the following predefined span values:
97.65625 kHz
195.3125 kHz
390.625 kHz

781.25 kHz
1.5625 MHz
3.125 MHz

6.25 MHz
12.5 MHz

Default is 12.5 MHz.

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IF LOOPBACK

DIGITAL
LOOPBACK

I/O LOOPBACK

Figure 5-4. Loopback

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INFO (Information)
Select Rem, Tx, Rx, Buf, Frame, Interface, Mask, Ref, or ID using the
◄ ► arrow keys, then press ENTER.

INFO: Rem Tx Rx Buffer Frame
Interface Mask Ref ID
These screens display information on the current configuration of the unit. Depending on
the choice selected, one of the following screens will be displayed: using the ◄ ► arrow
keys, then press ENT.

5.6.4.1

(InfoRem) - REMOTE CONTROL INFORMATION
This screen shows if the unit is in Local or Remote mode, and gives details of the
electrical interface type selected, the unit’s address, and the baud rate selected, etc.
Pressing ENT or CLR takes the user back to the previous menu.
Examples:

Remote M&C: Monitor Only
(Local Control only)
Remote M&C: RS485-4Wire
Address: 0001 19200 Baud
Remote M&C: 100BaseTx
IP Addr: 255.255.255.255

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(InfoTx) - TX INFORMATION
The information displayed here is as follows:

Tx: 1140.000 05000.000 TUR
8P 17/18 S EXT -20.0 ON N ▲▼
Top line:
Transmit Frequency and Data Rate (NOTE: Due to space limitations, the resolution of
displayed frequency is limited to 1 kHz, and data rate to 10Hz,)
FEC Encoder type (VIT = Viterbi, VRS=Viterbi + Reed-Solomon, TCM = Trellis
Coded + Reed-Solomon, TUR = Turbo)
Bottom line:
Modulation Type (Q = QPSK, B = BPSK, 8P = 8-PSK, 16=16-QAM).
Code Rate (2144 = 21/44, then 5/16, 1/2, 2/3, 3/4, 7/8, 17/18)
Scrambler state (S = Scrambler on, N = Scrambler off, I=IESS-315)
Clocking Mode (INT = internal, EXT = external, LOP = loop, ELP=external loop)
Output Power level
Transmit Output State (ON = on, OF = off, EO= external off)
TSI State (I = Transmit Spectral Inversion on, N = off)
Using ▲▼ arrow keys will display the following information:

Tx: C N N 35

▲▼

Top line:
Reed-Solomon code rates (C=Comtech(220,200), E=EF Data(225,205), I=IESS310(219,201).
Tx Clock Inversion (N=Normal, I=Inverted).
Tx Data Inversion (N=Normal, I=Inverted).
Tx Roll-Off (α) factor (20=20% roll-off, 35=35% roll-off)

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(InfoRx) – RX INFORMATION
The information displayed here is as follows:

Rx: 1140.000 05000.000 TUR
8P 17/18 D RX BUF +/-32k N ▲▼
Top line:
Receive Frequency and Data Rate (NOTE: Due to space limitations, the resolution of
displayed frequency is limited to 1 kHz, and data rate to 10Hz,)
FEC Decoder type (VIT = Viterbi, SEQ = Sequential, VRS=Viterbi + Reed-Solomon,
SRS=Sequential + Reed Solomon, TCM = Trellis Coded + Reed-Solomon, TUR =
Turbo)
Bottom line:
Demodulation type (Q = QPSK, B = BPSK, 8P = 8-PSK, 16=16-QAM).
Code Rate (2144 = 21/44, then 5/16, 1/2, 2/3, 3/4, 7/8, 17/18)
Descrambler state (D = Descrambler on, N = Descrambler off)
Buffer Source (IN = internal, RX = Rx satellite, TT = Tx terrestrial)
Buffer Clocking Mode (SAT = buffer disabled, BUF = buffer enabled)
Demod Sweep Acquisition range
RSI state (I = Receive Spectral Inversion on, N = off)
Using ▲▼ arrow keys will display the following information:

Rx: C N N 35

▲▼

Top line:
Reed-Solomon code rates (C=Comtech(220,200), E=EF Data(225,205), I=IESS310(219,201).
Rx Clock Inversion (N=Normal, I=Inverted).
Rx Data Inversion (N=Normal, I=Inverted).
Rx Roll-Off (α) factor (20=20% roll-off, 35=35% roll-off)

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(InfoBuffer) - BUFFER INFORMATION
Buffer:

Enabled

(Tx=Rx)
(ENT)

This displays if the buffer is enabled or disabled, shows the exact clocking mode
(TX=RX, or TX<> RX), and the buffer size. Pressing ENT takes the user back to the
previous menu.

5.6.4.5

(InfoFrame) – FRAMING AND EDMAC INFORMATION
Examples:

Framing: AUPC-Only, D&I++
(ENT or CLR)
Framing:AUPC-Only,EDMAC2
(ENT or CLR)
Framing: AUPC+EDMAC2
Master,0240
(ENT or CLR)
Framing: AUPC+EDMAC
Slave, 0241
(ENT or CLR)
This screen shows EDMAC mode, and shows if the unit is an EDMAC MASTER or
SLAVE, with the appropriate address. Pressing ENT or CLR takes the user back to the
previous menu.

5.6.4.6

(InfoInterface) – INTERFACE INFORMATION
This screen shows details of the electrical interface type of the main data port. If RS422,
V.35 or RS232 is selected, the menu will also indicate the operation of RTS/CTS.
Pressing ENT or CLR takes the user back to the previous menu.
Example:

Interface: RS422
(ENT)
RTS/CTS Loop, No Action
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(InfoMask) – ALARM MASK INFORMATION
This shows, in the same format as the CONFIG, MASK sub menu, which alarms are
currently masked. If an alarm is not masked, a blank is displayed in the relevant screen
position.

Mask: FIFO BPV TAIS
AGC EbNo BUF Ref

5.6.4.8

RAIS

(InfoRef) - FREQUENCY REFERENCE
Frequency Reference:
Internal 10 MHz

(ENT)

This shows the source of the frequency reference for the CDM-QX.

5.6.4.9

(InfoID) – CIRCUIT IDENTIFICATION
Circuit ID:
(ENT)
28 CHARACTER TST MESSAGE
This displays the user-defined Circuit ID string, which is entered via the UTIL, ID
screen. To return to the previous menu, press ENT. Backup devices do not have an ID.

5.6.5

SAVE/LOAD
SAVE/LOAD Configuration:
Save Load
(◄ ► ENT)
Select Save or Load using the ◄ ► arrow keys, then press ENT.
These sub-menus permit the user to store or load up to 10 different modem configurations
in the non-volatile memory of the modem.

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(Save/LoadSave) – SAVE CONFIGURATION
Selecting Save will display the following screen, if the selected location is empty:

Save Config to Location: 9
Empty
(▲ ▼ ENT)
However, if the location already contains data, the following screen will be displayed:

Save Config to Location: 9
11:10:29 23/12/03
(▲ ▼ ENT)
The user is shown the time and date stamp of the previously stored configuration, for
identification purposes.
Select the location to store the current configuration to, using the STarrow keys, then
press ENT. Locations 1 through 10 are available.
If the selected location does not contain a previously stored configuration, the following
screen is displayed:

Your Configuration has been
Saved to Location 9
(ENT)
Pressing ENT or CLR will take the user back to the previous menu.
If, however, the selected location contains a previously stored configuration, the
following screen is displayed:

Location 9 Contains Data!
Overwrite? NO YES
(◄ ► ENT)
Select NO or YES using the ◄ ► arrow keys, then press ENT.
Selecting YES will overwrite the existing configuration at the selected location.

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(Save/LoadLoad) – LOAD CONFIGURATION
Having selected Load, if there is a configuration stored at the selected location the
following screen will be displayed:

Load Config from Location: 9
11:10:29 23/12/03
(▲ ▼ ENT)
Note the data and time stamp identifying the stored configuration.
But if the selected location contains no data, the following screen will be displayed:

Load Config from Location 9
Empty
(▲ ▼ ENT)
Select the location to load a configuration from, using the STarrow keys, then press
ENT. Locations 1 through 10 are available.
If the selected location contains valid data, the following screen will be displayed:

New Config has been Loaded
from Location 9
(ENT)
Pressing ENT or CLR will take the user back to the previous menu.
If, however, the selected location does not contain valid data, the following screen will be
displayed:

Warning! Location 9
Contains No Data!

(ENT)

Pressing ENT or CLR will take the user back to the previous menu.

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UTILITY
UTILITY: RxBuffer Clock Ref
ID Display Firmware FAST
Select RxBuffer, Clock, Ref, ID, Display, Firmware or FAST using the
◄ ► arrow keys then press ENT.
According to the selection, the following sub-menus are displayed:

5.6.6.1

(UtilityRxBuffer) - BUFFER RECENTER
Press ENT to Re-Center
the Receive Buffer
Pressing ENT will cause a forced re-centering of the Plesiochronous/Doppler buffer.

5.6.6.2

(UtilityClock) - REAL-TIME CLOCK
Real-Time Clock:(◄ ►,▲ ▼,ENT)
Time=12:00:00 Date:24/04/03

IMPORTANT

Edit the time and date settings of the real-time clock. This is accomplished by
selecting the digit to be edited, using the WXarrow keys. The value of the digit is
then changed using the STarrow keys. Note that in accordance with
international convention, the date is shown in DAY-MONTH-YEAR format.
The user should then press ENT.

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(UtilityRef) - REFERENCE ADJUST
Internal Freq Ref: Adjust
Warm-up delay
(▲▼, ENT)
Fine adjustment of the Internal 10 MHz reference oscillator is possible through this
menu. Use the STarrow keys to edit the value, then press ENT. The range of values is
from –2048 to +2047.
Note: The numbers displayed here do not correspond to an exact frequency increment. A
user should perform this fine adjustment while using an external frequency counter,
connected to either:
a. the internal 10 MHz reference, or
b. the Tx Output, set for CW, and an exact center frequency of 1000 MHz, for
example.

5.6.6.4

(UtilityID) – CIRCUIT IDENTIFICATION
Edit Circuit ID: (◄ ►,▲ ▼,ENT)
28 CHARACTER TST MESSAGE
Edit the Circuit ID string, using the WXand STarrow keys. Only the bottom line is
available (28 characters). The cursor selects the position on the bottom line (◄ ►) and
the character is then edited (ST). The following characters are available:
Space (

) * +

, . / 0-9 and A-Z.

When the user has composed the string, press ENT. Backup devices in redundant groups
do not have an ID. If plug-in devices are to be grouped, the grouping should precede
assigning IDs so the group can be named instead of the individual devices.

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(UtilityDisplay) - DISPLAY BRIGHTNESS
Edit Display Brightness:
100%
(▲▼, ENT)
Edit the display brightness, using the STarrow keys. The user should then press ENT.

5.6.6.6

(UtilityFirmware) - FIRMWARE
This series of sub-menus permits the user to view information about the CDM-Qx
internal firmware. The modem can store two complete firmware images, and the user can
select which image will be loaded the next time the unit re-boots.

IMPORTANT

THESE MENUS ARE FOR DIAGNOSTIC PURPOSES. ONLY CHANGE AN
IMAGE IF INSTRUCTED TO DO SO BY COMTECH EF DATA CUSTOMER
SERVICE TECHNICIANS.

Firmware Images: Update-CPLD
Information Select (◄ ► ENT)
Select either Information or Select, using the WXarrow keys. The user should then
press ENT.
If the user selects Information, the following sub-menu is displayed:

F/W Information: Bootrom
Image#1 Image#2
CPLD
The user may select, using the WXarrow keys and ENT key, to view information about
the Bootrom, the 2 images, or the CPLD on the modulator or demodulator card.
Each image can be viewed as follows:

Image#x: Bulk Firmware (▲ ▼ ENT)
FWxxxxx 01/01/04
1.1.1
By using the STarrow keys, the user can view each component of the firmware image.

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If the user selects Select, the following sub-menu is displayed:

Current Active Image: #1
Next Reboot Image: #1 #2
The top line shows the current active image. On the bottom line the user may select,
using the ◄ ► arrow keys and ENT key, the image that will be active the next time the
unit is re-booted.
If Update-CPLD is selected, the following sub-menus are displayed:

RULE: Only one card must be
installed in the chassis!
Programming the CPLD requires only one card to be installed in the chassis. If this rule
has been exercised, this next menu will appear.

Update CPLD to v1.x.x?
No Yes
(◄ ► ENT)
Where v1.x.x is version number. Before selecting Yes, please check the current version
of the CPLD programmed on the Tx or Rx card
(UtilityFirmwareInformationCPLD). Select Yes if you want to update it to the
latest version and the following sub-menu is displayed:

Programming CPLD . . .
. . . PLEASE WAIT!
Every time CPLD programming is done (whether successful or not), always CYCLE
power if another card is to be programmed.

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(UtilityFAST) - FAST Code Options
FAST is the way to enable new options in the modem. Obtain the FAST code for the new
option from Comtech EF Data.

FAST – Select the module:
Base Slot1 Slot2 Slot3 Slot4
The Base refers to the base unit where you can view the redundancy option as well as the
CnC option. The Slot# refers to the cards where it is installed. If Base is selected, the
sub-menu will appear as follows:

FAST: Config View
Board S/N: 123456789

(Base)

If Slot# is selected, this submenu will appear (for example Slot1):

FAST – Slot#1: Mod Turbo
(◄ ► ENT)
Selecting Mod (in this case) will display the next sub-menu:

FAST: Config View
Board S/N: 123456789

(Mod#1)

If Turbo is selected, it will show this (for example in Slot1):

FAST: Config View
Board S/N: 123456789

(TPC#1)

If Config is selected in any case (base or slot#), it will display the following:

FAST Configuration
Edit Code
Demo Mode

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User can either select Edit Code or Demo Mode. If Edit Code is selected, the following
menu is displayed:

Edit 20 digit FAST Code:
00000000000000000000
ENT
Enter the code carefully. Use the WXarrow keys to move the cursor to each character.
Use the STarrow keys to edit the character, then press ENT. The modem will respond
with “Configured Successfully” if the new FAST option has been accepted as shown
below.

Configured Successfully
(ENT or CLR)

If, on the other hand, the FAST code is rejected, the following menu will be displayed:

FAST Code Rejected!
(ENT or CLR)
If Demo Mode is selected, the display will be as follows:

FAST Demo Mode: Off On
604669 seconds remain
The Demo Mode allows the user to use all FAST options with limited time. The demo
will last only 7 days. If demo is on, CnC is only allowed up to 2.5 Mbps.
If the user selects View, then the following menu is displayed, for example:

View Options: 01 (▲ ▼ ENT)
1:1 Redun
- Not Installed
Use the STarrow keys to scroll through each Option Number in turn. As the cursor
highlights each option, the description of the option will be displayed on the bottom line,
along with the information “Installed or Not Installed”.

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Chapter 6. FORWARD ERROR
CORRECTION OPTIONS

6.1

Introduction
As standard, the Modem is equipped with three Forward Error Correction
encoders/decoders – Viterbi, concatenated Reed-Solomon and Trellis (which is available
with the 8-PSK FAST option). The constraint lengths and encoding polynomials are not
only Open Network compatible (IESS-315), but are also Closed Network compatible
with the vast majority of existing modems from other manufacturers. Comtech EF Data
has performed compatibility testing to ensure inter-operability.
Turbo Coding represents a very significant development in the area of FEC, and
optionally, the modem may be fitted with a Turbo Product Codec. They are plug-in
daughter cards (SIMM modules) that are field upgradeable. The codec provides data rate
capability up to 20 Mbps, and code rates of:
•
•
•
•

Rate 5/16 (BPSK
Rate 21/44 (BPSK, QPSK)
Rate 3/4, and 7/8 (QPSK, 8-PSK, and 16-QAM)
Rate 17/18 (QPSK and 8-PSK)

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Viterbi
The combination of convolutional coding and Viterbi decoding has become an almost
universal standard for satellite communications. The Modem complies with the Intelsat
standards for Viterbi decoding with a constraint length of seven. This is a de facto
standard, even in a closed network environment, which means almost guaranteed interoperability with other manufacturer’s equipment. It provides very useful levels of coding
gain, and its short decoding delay and error-burst characteristics make it particularly
suitable for low data rate coded voice applications. It has a short constraint length, fixed
at 7, for all code rates. (The constraint length is defined as the number of output symbols
from the encoder that are affected by a single input bit.) By choosing various coding rates
(Rate 1/2, 3/4, or 7/8) the user can trade off coding gain for bandwidth compression. Rate
1/2 coding gives the best improvement in error rate, but doubles the transmitted data rate,
and hence doubles the occupied bandwidth of the signal. Rate 7/8 coding, at the other
extreme, provides the most modest improvement in performance, but only expands the
transmitted bandwidth by 14 %. A major advantage of the Viterbi decoding method is
that the performance is independent of data rate, and does not display a pronounced
threshold effect (i.e., does not fail rapidly below a certain value of Eb/No). Note that in
BPSK mode, the Modem only permits a coding rate of 1/2. Because the method of
convolutional coding used with Viterbi, the encoder does not preserve the original data
intact, and is called non-systematic.
Table 6-1. Viterbi Decoding Summary
FOR
Good BER performance - very useful coding gain.
Almost universally used, with de facto standards for
constraint length and coding polynomials
Shortest decoding delay (~200 bits) of any FEC scheme good for coded voice, VOIP, etc
Short constraint length produce small error bursts - good
for coded voice.
No pronounced threshold effect - fails gracefully.
Coding gain independent of data rate.

6–2

AGAINST
Higher coding gain possible with
other methods

CDM-Qx Satellite Modem
Forward Error Correction Options

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Reed-Solomon Outer Codec

IMPORTANT

It cannot be emphasized strongly enough that the purpose of the
concatenated Reed-Solomon is to dramatically improve the BER
performance of a link under given noise conditions. It should NOT be
considered as a method to reduce the link EIRP requirement to produce
a given BER. Factors such as rain-fade margin, particularly at Kuband, are extremely important, and reducing link EIRP can seriously
degrade the availability of such a link.

The concatenation of an outer Reed-Solomon Codec with Viterbi decoder first became
popular when Intelsat introduced it in the early 1990's. It permits significant
improvements in error performance without significant bandwidth expansion. The coding
overhead added by the R-S outer Codec is typically around 10%, which translates to a
0.4 dB power penalty for a given link. Reed-Solomon codes are block codes (as opposed
to Viterbi, which is convolutional), and in order to be processed correctly the data must
be framed and de-framed. Additionally, Reed-Solomon codes are limited in how well
they can correct errors that occur in bursts. This, unfortunately, is the nature of the
uncorrected errors from Viterbi decoders, which produce clusters of errors that are
multiples of half the constraint length. For this reason, the data must be interleaved
following R-S encoding, and is then de-interleaved prior to decoding. This ensures that a
single burst of errors leaving the Viterbi decoder is spread out over a number of
interleaving frames, so errors entering the R-S decoder do not exceed its capacity to
correct those errors.
In the case of the Modem, different R-S code rates are used, according to the mode of
operation:

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Closed Network Modes
A 220,200 code is used in transparent closed network modes, and a 200, 180 code is used
in framed (EDMAC) modes. (220, 200 means that data is put into blocks of 220 bytes, of
which 200 bytes are data, and 20 bytes are FEC overhead.) These two codes were chosen
because they fit well into Comtech EF Data’s clock generation scheme, and they have
almost identical coding gain. When Viterbi decoding is used as the primary FEC, an
interleaver depth of 4 is used. The increase in coding gain is at the expense of delay. The
interleaving/de-interleaving delay and the delay through the decoder itself can be as high
as 25 kbps. At very low data rates, this equates to several seconds, making it highly
unsuitable for voice applications. Additionally, the de-interleaver frame synchronization
method can add significantly to the time taken for the demodulator to declare acquisition.
A characteristic of concatenated R-S coding is the very pronounced threshold effect. For
any given modem design, there will be a threshold value of Eb/No below which the
demodulator cannot stay synchronized. This may be due to the carrier-recovery circuits,
or the synchronization threshold of the primary FEC device, or both. In the Modem, and
Rate 1/2 operation, this threshold is around 4 dB Eb/No. Below this value, operation is
not possible, but above this value, the error performance of the concatenated R-S system
produces exceptionally low error rates for a very small increase in Eb/No.

CAUTION

Care should be taken not to operate the demodulator near its sync
threshold. Small fluctuations in Eb/No may cause total loss of the link,
with the subsequent need for the demodulator to re-acquire the signal.

Table 6-2. Concatenated R-S Coding Summary
FOR

AGAINST

Exceptionally good BER performance
- several orders of magnitude
improvement in link BER under given
link conditions.
Very small additional bandwidth
expansion

Very pronounced threshold effect - does not fail
gracefully in poor Eb/No conditions. Additional coding
overhead actually degrades sync threshold, and reduces
link fade margin.
Significant processing delay (~25 kbits) - not good for
voice, or IP applications
Adds to demod acquisition time.

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Trellis Coding
In the other FEC methods described here, the processes of coding and modulation are
independent - the FEC codec has no knowledge of, or interaction with the modulator.
However, there are schemes in which the coding and modulation are combined together,
where the encoder places FEC symbols in a precise manner into the signal constellation.
This can yield an overall improvement in performance, and is used in higher-order
modulation schemes, such as 8-PSK, 16-PSK, 16-QAM, etc. When convolution coding
is used, the overall coded modulation approach is referred to as Trellis Coded Modulation
(TCM). Ungerboeck was an early pioneer, and developed optimum mapping and
decoding schemes. However, the decoding scheme was seen as complex, and expensive,
and Qualcomm Inc. developed a variation on the theme, which uses a Viterbi decoder at
the core, surrounded by adjunct processing. The scheme is able to achieve performance
very close to the optimum Ungerboeck method, but with far less complexity, and is called
pragmatic Trellis Coded Modulation.
Now, Intelsat recognized that, as more and more high power transponders are put in to
service, the transponders are no longer power limited, but bandwidth limited. In order to
maximize transponder capacity, they looked at 8-PSK as a method of reducing the
occupied bandwidth of a carrier, and adopted Qualcomm’s pragmatic TCM, at Rate 2/3.
A Rate 2/3 8-PSK/TCM carrier occupies only 50% of the bandwidth of a Rate 1/2 QPSK
carrier. However, the overall coding gain of the scheme is not adequate by itself, and so
Intelsat’s IESS-310 specification requires that the scheme be concatenated with an outer
R-S codec. When combined, there is a threshold value of Eb/No of around 6 dB, and
above approximately 7 dB, the bit error rate is better than 1 x 10-8.
The detractions of the concatenated R-S approach apply here also, along with more
stringent requirements for phase noise and group delay distortion – the natural
consequences of the higher-order modulation.
The modem fully implements the FEC, but not the framing of the IESS-310 specification
at data rates up to 18 Mbps. In accordance with the specification, the R-S outer code can
be disabled. Performance curves for both cases are shown in the following Figures.
Table 6-3. 8-PSK/TCM Coding Summary
FOR

AGAINST

Exceptionally bandwidth efficient
compared to QPSK

Needs concatenated R-S outer codec to give
acceptable coding gain performance
Demod acquisition threshold much higher than for
QPSK
8-PSK is more sensitive to phase noise and
group delay distortion than QPSK

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Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

6.5

Turbo Product Codec (Hardware Option)

6.5.1

Introduction
Turbo coding is an FEC technique developed
within the last few years, which delivers
significant performance improvements
compared to more traditional techniques. Two general classes of Turbo Codes have been
developed, Turbo Convolutional Codes (TCC), and Turbo Product Codes (TPC, a block
coding technique). Comtech EF Data has chosen to implement an FEC codec based on
TPC. A Turbo Product Code is a 2 or 3 dimensional array of block codes. Encoding is
relatively straightforward, but decoding is a very complex process requiring multiple
iterations of processing for maximum performance to be achieved.
Unlike the popular method of concatenating a Reed-Solomon codec with a primary FEC
codec, Turbo Product Coding is an entirely stand-alone method. It does not require the
complex interleaving/de-interleaving of the R-S approach, and consequently, decoding
delays are significantly reduced. Furthermore, the traditional concatenated R-S schemes
exhibit a very pronounced threshold effect – a small reduction in Eb/No can result in total
loss of demod and decoder synchronization. TPC does not suffer from this problem – the
demod and decoder remain synchronized down to the point where the output error rate
becomes unusable. This is considered to be a particularly advantageous characteristic in a
fading environment. Typically, in QPSK, 8-PSK and 16-QAM TPC modes the demod
and decoder can remain synchronized 2 – 3 dB below the Viterbi/Reed-Solomon or TCM
cases.
Comtech now provides the best Forward Error Correction technology currently available,
offering a very broad range of TPC code rates, combined with the entire range of
modulation types, from BPSK to 16-QAM.

6.5.2

The Evolution of TPC in Comtech Products
When Comtech EF Data first introduced the Turbo Coding option in 1999, only Rate 3/4
QPSK was offered. Further work permitted the addition of Offset QPSK operation. Two
further code rates - Rate 21/44 BPSK (very close to Rate 1/2) and Rate 5/16 BPSK (very
close to Rate 1/3) were then made available.
(These two rates were developed to address transmission from very small antennas,
where ITU flux density limits may be an issue. The combination of code rate and BPSK
modulation provides wide spreading, and hence reduces flux density.)
In 2002, the new second generation TPC option was released. This has added data rate
capability up to 20 Mbps, in addition to Rate 7/8 and Rate 17/18 capability. The Rate 7/8
TPC is extremely powerful, offering performance very close to the original Rate 3/4
TPC, but using 15% less bandwidth. Note also that the Rate 17/18 TPC adds just 5% FEC
overhead, but yields almost identical coding gain to Rate 1/2 Viterbi at a BER of 1 x 10-7.
Below is a listing of all the available TPC modes and rates in the CDM-Qx.

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Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Table 6-4. Available TPC Modes

6.5.3

Code Rate/Modulation
Rate 21/44 BPSK
Rate 5/16 BPSK
Rate 21/44 QPSK
Rate 3/4 QPSK
Rate 3/4 8-PSK
Rate 3/4 16-QAM
Rate 7/8 QPSK
Rate 7/8 8-PSK
Rate 7/8 16-QAM
Rate 17/18 QPSK

32 kbps to 4.772 Mbps
32 kbps to 3.125 Mbps
32 kbps to 10 Mbps
32 kbps to 15 Mbps
288 kbps to 20 Mbps
384 kbps to 20 Mbps
32 kbps to 17.5 Mbps
336 kbps to 20 Mbps
448 kbps to 20 Mbps
32 kbps to 18.88 Mbps

Data Rate Range

Rate 17/18 8-PSK

362.7 kbps to 20 Mbps

End-to-End Processing Delay
In many cases, FEC methods that provide increased coding gain do so at the expense of
increased processing delay. However, with TPC, this increase in delay is very modest.
The table below shows, for the Modem, the processing delays for the major FEC types,
including the three TPC modes:
Table 6-5. Turbo Product Coding processing delay comparison
FEC Mode (64 kbps data rate)

End-to-end delay, ms

Viterbi, Rate 1/2

Viterbi Rate 1/2 + Reed-Solomon

266

Turbo Product Coding, Rate 3/4

Turbo Product Coding, Rate 21/44, BPSK

Turbo Product Coding, Rate 5/16, BPSK

48
245 *

Turbo Product Coding, Rate 7/8

Turbo Product Coding, Rate 17/18

Note that in all cases, the delay is inversely proportional to data rate, so for 128 kbps, the
delay values would be half of those shown above. It can be seen that the concatenated
Reed-Solomon cases increase the delay significantly (due mainly to interleaving/deinterleaving), while the TPC cases yield delays, which are much less.
* A larger block is used for the Rate 7/8 code, which increases decoding delay.

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CDM-Qx Satellite Modem
Forward Error Correction Options

6.5.4

Revision 5
MN/CDMQx.IOM

Comparison of all TPC Modes
Eb/No at
BER = 10-6
Guaranteed
(Typical in
parentheses)

Eb/No at
BER = 10-8
Guaranteed
(Typical in
parentheses)

Spectral
Efficiency

Symbol Rate

Occupied *
Bandwidth
for 1 Mbps
Carrier

QPSK Rate 1/2 Viterbi *

6.0 dB
(5.5 dB)

7.3 dB
(6.8 dB)

1.00 bits/Hz

1.0 x bit rate

1190 kHz

BPSK Rate 21/44 Turbo

2.9 dB
(2.6 dB)

3.3 dB
(3.0 dB)

0.48 bits/Hz

2.1 x bit rate

2493 kHz

BPSK Rate 5/16 Turbo

2.4 dB
(2.1 dB)

2.8 dB
(2.5 dB)

0.31 bits/Hz

3.2 x bit rate

3808 kHz

QPSK Rate 1/2 Turbo

2.9 dB
(2.6 dB)

3.2 dB
(2.8 dB)

0.96 bits/Hz

1.05 x bit rate

1246 kHz

QPSK Rate 3/4 Turbo

3.8 dB
(3.3 dB)

4.4 dB
(4.0 dB)

1.50 bits/Hz

0.67 x bit rate

793 kHz

QPSK Rate 7/8 Turbo

4.3 dB
(4.0 dB)

4.5 dB
(4.2 dB)

1.75 bits/Hz

0.57 x bit rate

678 kHz

QPSK Rate 17/18 Turbo

6.4 dB
(6.0 dB)

6.9 dB
(6.5 dB)

1.90 bits/Hz

0.53 x bit rate

626 kHz

8-PSK Rate 2/3 TCM **
and R-S (IESS-310)

6.5 dB
(5.6 dB)

6.9 dB
(6.0 dB)

1.82 bits/Hz

0.56 x bit rate

666 kHz

8-PSK Rate 3/4 Turbo

6.2 dB
(5.7 dB)

6.8 dB
(6.3 dB)

2.25 bits/Hz

0.44 x bit rate

529 kHz

8-PSK Rate 7/8 Turbo

7.0 dB
(6.6dB)

7.2 dB
(6.8 dB)

2.62 bits/Hz

0.38 x bit rate

453 kHz

8-PSK Rate 17/18 Turbo

9.3 dB
(8.9 dB)

10.3dB
(9.9 dB)

2.85 bits/Hz

0.35 x bit rate

377 kHz

16-QAM Rate 3/4 Turbo

7.4 dB
(7.0 dB)

8.2 dB
(7.7 dB)

3.00 bits/Hz

0.33 x bit rate

396 kHz

16-QAM Rate 7/8 Turbo

8.1 dB
(7.7 dB)

8.3 dB
(7.9 dB)

3.50 bits/Hz

0.28 x bit rate

340 kHz

16-QAM Rate 3/4 **
Viterbi/Reed-Solomon

8.1 dB
(7.5 dB)

8.6 dB
(8.0 dB)

2.73 bits/Hz

0.37 x bit rate

435 kHz

16-QAM Rate 7/8 **
Viterbi/Reed-Solomon

9.5 dB
(9.0 dB)

10.1 dB
(9.5 dB)

3.18 bits/Hz

0.31 x bit rate

374 kHz

Mode

*
**

The occupied bandwidth is defined at the width of the transmitted spectrum taken at the –10 dB
points on the plot of power spectral density. This equates to 1.19 x symbol rate for the modem
transmit filtering.
Included for comparative purposes

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CDM-Qx Satellite Modem
Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

It can be seen that the 8-PSK Rate 3/4 Turbo performance closely approaches that of the
Rate 2/3 TCM/Reed-Solomon case – the BER performance is within approximately 0.4
dB. However, it should be noted that the Rate 3/4 Turbo mode is 20% more bandwidth
efficient than the TCM case. The additional advantages of Turbo (lower delay,
performance during fades etc) should also be considered.
Table 6-6. Turbo Product Coding Summary
FOR
Exceptionally good BER performance - significant improvement compared
with every other FEC method in use today
No pronounced threshold effect - fails gracefully
Exceptional bandwidth efficiency
Coding gain independent of data rate (in this implementation)
Low decoding delay
Easy field upgrade in Modem

6–9

AGAINST
Nothing!

CDM-Qx Satellite Modem
Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Eb/No in dB
1

1E-1
Uncoded BPSK/QPSK

Viterbi
Decoding

1E-2

Typical
Performance
1E-3

1E-4

1E-5

1E-6

Specification
limit, Rate 7/8
Coding

1E-7

1E-8
Specification
limit, Rate 3/4
Coding

Specification
limit Rate 1/2
Coding
1E-9
BER

Figure 6-1. Viterbi Decoding
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CDM-Qx Satellite Modem
Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Eb/No in dB
1

1E-1

Viterbi with
concatenated
RS 220,200
Outer Code

Uncoded BPSK/QPSK

1E-2
Sync
threshold,
Rate 3/4
1E-3
Sync
threshold,
Rate 7/8
1E-4

1E-5

Combined sync
threshold, demod
and Viterbi
Decoder, Rate 1/2

Specification
Limit Rate 1/2
and 220,200
Outer Code

1E-6

1E-7

Specification
Limit Rate 3/4
and 220,200
Outer Code

Typical performance
1E-8

Specification
Limit Rate 7/8
and 220,200
Outer Code
1E-9
BER

Figure 6-2. Viterbi with concatenated R-S Outer Code
6–11

CDM-Qx Satellite Modem
Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Eb/No in dB
1

1E-1

8-PSK/TCM Rate 2/3
Decoding, with and
without 219, 201 RS
Outer Code

Uncoded BPSK/QPSK

1E-2
Performance with CDM-Qx

1E-3

1E-4

Typical
Performance

1E-5

1E-6

1E-7

1E-8
Specification limit
Rate 2/3 Coding and
219, 201 RS Outer Code
1E-9
BER

Specification
limit, Rate 2/3
Coding
6

Figure 6-3. 8-PSK/TCM Rate 2/3 with and without concatenated R-S Outer Code

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CDM-Qx Satellite Modem
Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Eb/No in dB
1E-1

1
12

Comtech Turbo Product Codec
Rate 3/4 QPSK, 8-PSK
and 16-QAM

Uncoded
BPSK/QPSK
1E-2
Performance with CDM-Qx

Uncoded
16-QAM
1E-3
Spec limit
Rate 3/4
8-PSK

Uncoded
8-PSK

1E-4
Spec
Speclimit
limit
Rate
Rate3/4
3/4
QPSK/OQPSK
QPSK
1E-5

1E-6

1E-7
Spec limit
Rate 3/4
16-QAM
1E-8
Typical performance

1E-9
BER

1
12

Figure 6-4. Comtech EF Data Turbo Product Codec
Rate 3/4 QPSK, 8-PSK and 16-QAM

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CDM-Qx Satellite Modem
Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Eb/No in dB
1

1E-1

Comtech Turbo Product Codec
Rate 7/8 QPSK, 8-PSK
and 16-QAM

Uncoded
BPSK/QPSK
1E-2
Performance with CDM-Qx

Uncoded
16-QAM

1E-3
Spec limit
Rate 7/8
8-PSK

Spec limit
Rate 7/8
QPSK/OQPSK
QPSK

Uncoded
8-PSK

1E-4

1E-5

1E-6

1E-7
Spec limit
Rate 7/8
16-QAM
1E-8
Typical performance
1E-9
BER

Figure 6-5. Comtech EF Data Turbo Product Codec
Rate 7/8 QPSK, 8-PSK and 16-QAM

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CDM-Qx Satellite Modem
Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Eb/No in dB
1

1E-1

Comtech Turbo Product Codec
Rate 1/2 QPSK
Rate 17/18 QPSK
and 8-PSK

Uncoded
BPSK/QPSK
1E-2
Performance with CDM-Qx

Uncoded
8-PSK

1E-3

1E-4
Spec limit
Spec limit
Rate 17/18
Rate 17/18
QPSK/OQPSK
QPSK

Spec
Speclimit
limit
Rate
Rate 1/2
1/2
QPSK/OQPSK
QPSK
1E-5

1E-6

1E-7
Spec limit
Rate 17/18
8-PSK
1E-8

Typical
performance
1E-9
BER

Figure 6-6. Rate 1/2 QPSK, Rate 17/18 QPSK and Rate 17/18 8-PSK

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Forward Error Correction Options

Revision 5
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Eb/No in dB
1

1E-1

Comtech Turbo Product Codec
Rate 21/44 BPSK
Rate 5/16 BPSK

1E-2

1E-3

Spec limit
Rate 5/16
BPSK
Spec limit
Rate 21/44
BPSK

1E-4

Uncoded
BPSK/QPSK

1E-5

1E-6

1E-7

1E-8
Typical
performance
1E-9
BER

Figure 6-7. Rate 21/44 BPSK and Rate 5/16 BPSK Turbo

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Forward Error Correction Options

Revision 5
MN/CDMQx.IOM

Eb/No in dB
1

1E-1

16-QAM Viterbi, Rate 3/4 and Rate 7/8
with 220,200 RS Outer Code
Uncoded BPSK/QPSK

1E-2

Uncoded 16-QAM

1E-3

1E-4

Specification
limit Rate 7/8
Viterbi and
220,200 RS
Outer Code

1E-5
Typical
Performance

1E-6

1E-7

1E-8
Specification limit Rate
3/4 Viterbi and 220,200
RS Outer Code
1E-9
BER

Figure 6-8. 16-QAM Viterbi, Rate 3/4 and Rate 7/8 with 220,200 R-S Outer Code

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Forward Error Correction Options

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Notes:

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6–18

Chapter 7. EDMAC CHANNEL

7.1

Theory Of Operation
As explained earlier, EDMAC is an acronym for Embedded Distant-end Monitor And
Control. This is a feature, which permits the user to access the M&C features of modems
that are at the distant-end of a satellite link.
This is accomplished by adding extra information to the user’s data, but in a manner,
which is completely transparent to the user.
On the transmit side:
The data is split into frames - each frame containing 1008 bits (except Rate 21/44 BPSK
Turbo, or when the data rates exceed 2048 kbps, where the frame length is 2928 bits, and
Rate 5/16 BPSK Turbo where the frame length is 3072 bits). 48 bits in each frame are
overhead, and the rest of these bits are the user’s data. This increases the rate of
transmission by 5% (approximately 1.5% for the Turbo BPSK cases, and for all data rates
greater than 2.048 Mbps). For example, if the user’s data rate is 64 kbps, the actual
transmission rate will now be at 67.2 kbps.
At the start of each frame a 12-bit synchronization word is added. This allows the
demodulator to find and lock to the start of frame. At regular intervals throughout the
frame, additional data bytes and flag bits are added (a further 36 bits in total). It is these
additional bytes, which convey the M&C data.

7–1

CDM-Qx Satellite Modem
EDMAC Channel

Revision 5
MN/CDMQx.IOM

When framing is used, the normal V.35 scrambler is no longer used. This V.35 approach
is called ‘self synchronizing’, because in the receiver, no external information is required
in order for the de-scrambling process to recover the original data. The disadvantage of
this method is that it multiplies errors. On average, if one bit error is present at the input
of the descrambler, 3 output errors are generated. However, there is an alternative when
the data is in a framed format. In this case, a different class of scrambler may be used one which uses the start of frame information to start the scrambling process at an exact
known state. In the receiver, having synchronized to the frame, the de-scrambler can
begin its processing at exactly the right time. This method does not multiply errors, and
therefore has a clear advantage over V.35 scrambling. This is fortunate, as there is a
penalty to be paid for adding the framing. By adding the extra 5% to the transmitted data
rate, the effective Eb/No seen by the user will degrade by a factor of 10 log (1.05), or
0.21 dB (0.07 dB in the case of the two BPSK Turbo rates). The use of an externally
synchronized scrambler and descrambler almost exactly compensates for this
degradation. The net effect is that the user will see effectively identical BER performance
whether framing is used or not.
On the receive side:
When the demodulator locks to the incoming carrier, it must go through the additional
step of searching for, and locking to the synchronization word. This uniquely identifies
the start of frame, and permits the extraction of the overhead bytes and flag bits at the
correct position within the frame. In addition, the start of frame permits the de-scrambler
to correctly recover the data. The user’s data is extracted, and sent through additional
processing, in the normal manner. The extracted overhead bytes are examined to
determine if they contain valid M&C bytes.

7.2

M&C Connection
Data to be transmitted to the distant-end is sent to a local unit via the remote control port.
A message for the distant-end is indistinguishable from a ‘local’ message - it has the
same structure and content, only the address will identify it as being for a distant-end
unit.
Before the M&C data can be successfully transmitted and received, pairs of units must be
split into EDMAC Masters and EDMAC Slaves. Masters are local to the M&C
Computer, and Slaves are distant-end.

7–2

CDM-Qx Satellite Modem
EDMAC Channel

Revision 5
MN/CDMQx.IOM

Now, a unit that has been designated an EDMAC master not only responds to its own
unique bus address, but it will also be configured to listen for the address, which
corresponds to its EDMAC Slave. When a complete message packet has been received by
the EDMAC Master, it will begin to transmit this packet over the satellite channel, using
the overhead bytes, which become available.
Note: The ‘normal’ protocol for the message packet is not used over the satellite path, as
it is subject to errors. For this reason, a much more robust protocol is used which
incorporates extensive error checking.
At the distant-end, the EDMAC slave, configured for the correct address, receives these
bytes, and when a complete packet has been received, it will take the action requested,
and then send the appropriate response to the EDMAC Master, using the return overhead
path on the satellite link. The EDMAC Master assembles the complete packet, and
transmits the response back to the M&C Computer.
Apart from the round-trip satellite delay, the M&C Computer does not see any difference
between local and distant-end units - it sends out a packet, addressed to a particular unit,
and gets back a response. It can be seen that the EDMAC Master simply acts as
forwarding service, in a manner, which is completely transparent.

7.3

Setup Summary
To access a distant-end unit:
Designate a Master/Slave pair - Master at the local-end, Slave at the distant-end.
On the local-end unit, enable framing, and EDMAC, defines the unit as
MASTER, then enter the bus address. This is constrained to be ‘base 10' meaning
that only addresses such as 10, 20, 30, 40 etc, are allowed.
Choose a unique bus address for the distant-end. This should normally be set to
the ‘base 10' address + 1. For example, if the MASTER unit is set to 30, choose
31 for the distant-end unit.
On the distant-end unit, enable framing, and EDMAC, defines the unit as
SLAVE, then enter the bus address. The orange EDMAC Mode LED should be
illuminated.
Set the local-end unit to RS485 remote control, and set the bus address of this
local unit. The orange Remote Mode LED should be illuminated.
Once the satellite link has been established, connect the M&C Computer, and
begin communications, with both the local and distant end units.
NOTE: EDMAC modes are fully compatible with AUPC modes.

7–3

CDM-Qx Satellite Modem
EDMAC Channel

Revision 5
MN/CDMQx.IOM

This page is intentionally left blank.

7–4

Chapter 8. AUTOMATIC UPLINK
POWER CONTROL

8.1

Introduction
Automatic Uplink Power Control (AUPC) is a feature whereby a local modem is
permitted to adjust its own output power level in order to attempt to maintain the Eb/No
at the remote modem.
The user SHALL obtain permission from the Satellite
Operator to use this feature.
WARNING

Improper use of this feature could result in a transmitting
terminal seriously exceeding its allocated flux density on the
Operator’s satellite. This could produce interference to
other carriers, and could cause transponder saturation
problems
To accomplish this, the framed (EDMAC) mode of operation must be used. The remote
modem constantly sends back information about the demodulator Eb/No using reserved
bytes in the overhead structure. The local modem then compares this value of Eb/No with
a pre-defined target value. If the Remote Eb/No is below the target, the local modem will
increase its output power, and hence, a closed-loop feedback system is created over the
satellite link. A particularly attractive benefit of this feature is that whenever framed
operation is selected, the remote demodulator’s Eb/No can be viewed from the front
panel display of the local modem. Note also that AUPC can be used simultaneously with
EDMAC.

8–1

CDM-Qx Satellite Modem
Automatic Uplink Power Control (AUPC)

Revision 5
MN/CDMQx.IOM

There are several important parameters associated with this mode of operation, and the
user needs to understand how the AUPC feature works, and the implications of setting
these parameters.

8.2

Setting AUPC Parameters
1. The user, under the menu (CONFIG, MODE) first ensures that EDMAC is
selected. EDMAC may be selected as IDLE, or the unit may be defined as an
EDMAC Master or Slave. The important consideration is that EDMAC framing
should be enabled.
2. The user should verify that the remote modem also has EDMAC framing
enabled.
3. The user, under the menu (CONFIG, TX, POWER) sets the nominal output
power of the modem. This is done by selecting the MANUAL mode, then editing
the TX output power level displayed.
4. The user will then select AUPC as the operating mode. At this point the user will
be prompted to define four key parameters:

8.2.1

Target Eb/No
This is value of Eb/No that the user desires to keep constant at the remote modem.
If the Eb/No exceeds this value, the AUPC control will reduce the TX output power, but
will never drop below the nominal value set.
If the Eb/No falls below this value, the AUPC control will increase the TX output power,
but will never exceed the value determined by the parameter MAX RANGE.
•
•
•
•

8.2.2

The minimum value the user can enter is 0.0 dB
The maximum value the user can enter is 9.9 dB
The default value is 3.0 dB
The resolution is 0.1 dB

Max Range
This defines how much the modem is permitted to increase the output level, under AUPC
control.
• The minimum value the user can enter is 0 dB
• The maximum value the user can enter is 9 dB
• The default value is 1 dB
• The resolution is 1 dB

8–2

CDM-Qx Satellite Modem
Automatic Uplink Power Control (AUPC)

8.2.3

Revision 5
MN/CDMQx.IOM

Alarm
This parameter defines how the user wants the modem to act if, under AUPC control, the
maximum power limit is reached.
The two choices are:
• NONE (no action)
• TX ALARM (generate a Tx alarm)
The default setting is NONE.

8.2.4

Demod Unlock
This defines the action the modem will take if the remote demodulator loses lock.
The two choices are:
• NOMINAL (reduce the Tx Output Power to the nominal value)
• MAXIMUM (increase the Tx Output Power to the maximum value permitted by
the parameter MAX RANGE)
The default setting is NOMINAL.
(Note that if the local demod loses lock, the modem will automatically move its output
power to the nominal value.)

8.3

Compensation Rate
As with any closed-loop control system, the loop parameters must be chosen to ensure
stability at all times. Several features have been incorporated to ensure that the AUPC
system does overshoot, or oscillate.
First, the rate at which corrections to the output power can be made is fixed at once every
4 seconds. This takes into account the round trip delay over the satellite link, the time
taken for a power change to be reflected in the remote demodulator’s value of Eb/No, and
other processing delays in the modems.
Second, if the comparison of actual and target Eb/No yields a result that requires a
change in output power, the first correction made will be 80% of the calculated step. This
avoids the possibility of overshoot. Subsequent corrections are made until the difference
is less than 0.5 dB. At this point, the output power is only changed in increments of 0.1
dB, to avoid ‘hunting’ around the correct set point.

8–3

CDM-Qx Satellite Modem
Automatic Uplink Power Control (AUPC)

8.4

Revision 5
MN/CDMQx.IOM

Monitoring
The remote demodulator’s value of Eb/No can be monitored at all times, either from the
front panel (MONITOR, AUPC) or via the remote control interface. The resolution of
the reading is 0.2 dB. For all values greater than or equal to 16 dB, the value 16.0 dB will
be displayed. As long as framing is enabled, the value will still be available, even though
AUPC may be disabled.
Also displayed is the current value of Tx power increase. If EDMAC framing is enabled,
but AUPC is disabled, this will indicate 0.0 dB. This value is also available via the
remote control interface.

CAUTION

Comtech EF Data strongly cautions against the use of large values of
permitted power level increase under AUPC control. Users should
consider using the absolute minimum range necessary to improve rainfade margin

8–4

Chapter 9. DoubleTalk™
Carrier-in-Carrier®
OPERATION

The Modem optionally incorporates a proprietary technology licensed from Applied
Signal Technology, Inc. called DoubleTalk™, hereafter referred to as DoubleTalk
Carrier-In-Carrier (CnC) when implemented in Comtech EF Data modems. CnC
essentially allows two carriers to share the same channel.
Traditional full-duplex links utilize frequency division multiplexing to allow
communications in two directions. This requires allocating two frequency bands, one for
each direction (A and B). CnC allows the two carriers to reside on the same center
frequency allowing the duplex link to consume half the bandwidth as that of FDMA.
All of the following requirements must be met before carrier in carrier will function
correctly.
1. Both of the earth stations must be able to see each other’s carriers.
2. The modulator and demodulator must be “grouped” together for CnC to operate.
3. The relative power level between the two carriers must be < ± 10 dB of each
other. For optimal performance the carriers should be < ± 7 dB of each other.
4. The symbol rate ratio of the two carriers should be < 3:1 (either way).
It is recommended that the user start with the traditional FDMA configuration as shown
in Figure 10-1. This allows the user to establish the links, make sure the modems and RF
equipment are all functioning correctly and that a reasonable Eb/No has been set in each
direction for the modulation and code rate selected.
Then the modem generating the “B” carrier in this example should be relocated in
frequency to be “on top” of carrier “A”. At this point the demodulator-receiving carrier
“A” will loose lock. The carrier in carrier function must now be enabled in the Rx
configuration menus. Once CnC is turned on the demodulator will perform a search for a
9–1

CDM-Qx Satellite Modem
Carrier-in-Carrier Operation

Revision 5
MN/CDMQx.IOM

copy of the outbound modulators signal in time and frequency within the composite
signal received by the demodulator.
When the search algorithm has found the carrier, the modem front panel will report
search successful! It will also display an accurate value for the delay of the signal. The
demodulator will then reconfigure itself to match the delay value, cancel out the
interfering carrier (user’s outbound) then lock to and demodulate the desired carrier.
The modem is like all Comtech EF Data modems in that it has a full compliment of
receive monitored parameters. But for CnC operation a new parameter has been added.
To access this feature, change the menu from config Rx to monitor Rx, CnC and the
following parameters will be displayed. The normal BER, Eb/No and the new is the ratio
between the interferer and the desired carriers. The value display is the difference in dB
of the interferer over the desired carrier. This value is signed as the interferer (which the
user side of the link has control over) can be greater or less than the desired you are
trying to receive. This is an invaluable piece of information as with two carriers on top of
each other it is otherwise impossible to accurately tell if one side or the other should
experience a fade. The CnC monitor menu will also report the frequency offset between
the two carriers.
Once this side of the link is configured and running properly, the other side of the link
must be configured so that the Rx frequency is the same as the Tx and CnC is turned on.
At this point both sides of the link should be locked and passing traffic normally.
Once the links have been configured such that the Eb/No values with good weather
conditions are such that there is an appropriate fade margin, record the ratio value so that
between the Eb/No value of the desired and the ratio value the user can determine if the
link has degraded.
If the outbound carrier should go down the demodulator may drop sync but will relock to
the desired carrier. When the outbound carrier returns the demod may be able to relock
rapidly if the outage was brief or it may have to perform another search first. If the
desired carrier should go down the demodulator will continue to cancel the outbound but
will be unlocked with respect to the desired carrier. When the carrier returns the demod
will relock.
While there are several parameters that can be configured when using CnC, it is
recommend to leave them set to the factory default settings. These include changing the
minimum delay value (in milli seconds) for the search function. The typical satellite
delay will range from about 230 to 270 ms. If the minimum value is increase to say 200
ms the acquisition time will not be significantly improved and if the unit should be tested
at the IF level in the future it would not lock as the delay would be in the micro seconds.
The maximum delay can be decreased from 290 ms, but again the acquisition time will
not be significantly improved. The other parameter is the reacquisition delay value. This
determines how long the demodulator will wait to perform another search for the
outbound carrier.

9–2

CDM-Qx Satellite Modem
Carrier-in-Carrier Operation

Revision 5
MN/CDMQx.IOM

Traditional FDMA System Without CnC
A

Uplink
Transponder

Downlink
Transponder

CDM-Qx System With CnC
A
Uplink
Transponder

A
Downlink
Transponder

Figure 10-1. Transponder Utilization with and without CnC®

9–3

CDM-Qx Satellite Modem
Carrier-in-Carrier Operation

Revision 5
MN/CDMQx.IOM

Notes:

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9–4

Chapter 10. REDUNDANCY

Redundancy is built into the modem and can be enabled using the FAST optioning.
Redundancy can be selected so as to perform back up in the following scenarios:
•
•
•

1:1, (one modulator for one modulator), (one demodulator for one
demodulator), (one modem for one modem)
1:2, (one modulator for two modulators), (one demodulator for two
demodulators)
1:3, (one modulator for three modulators), (one demodulator for three
demodulators)

Location of the modules in the chassis is critical for correct operation of the redundancy
functions. When single modules are being backed up the back up unit must be located in
the lower right-hand slot as viewed from the rear. When modules grouped as modems
are being configured as redundant the back up modem has to be located in the right hand
column of slots, with the modulator on top.
If a 1:1 modulator and a 1:1 demodulator configuration is desired, group the boards as
modems and set up as described above.
Redundancy switching is implemented after the data interface. This means that the unit
or units designated as the back ups do not require a data interface that matches the online
units or an interface at all to operate as a back up.
Note: CEFD recommends that at least one extra interface be purchased, so that if an interface
should fail in the field the interface can be replaced. This is easily accomplished by removing the
modulator or demodulator, removing four screws, replacing the interface and reinstalling the four
screws.

10–1

CDM-Qx Satellite Modem
Redundancy

Revision 5
MN/CDMQx.IOM

Notes:

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10–2

Chapter 11. ETHERNET
MANAGEMENT

11.1

Introduction
The base modem is equipped with an RJ-45, 10/100BaseT Ethernet management
interface used for monitor and control purposes. This chapter of the manual will provide
a high-level overview of the functionality provided by this interface.

11.2

Ethernet Management Interface Protocols
The modem 10/100BaseT Ethernet Management Interface supports three (3) different
management protocols:
•
•
•

IMPORTANT

Web Server interface for complete product management
SNMP with public and private MIB
Telnet interface for remote product M&C

Please make sure the unit is in Ethernet Remote Mode (Config,Remote,Ethernet)
in order to access the Web server, SNMP, or Telnet. It’s not recommended to do
write access using Web, SNMP, and Telnet at the same time.

11–1

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

11.3

Revision 5
MN/CDMQx.IOM

Web Server (HTTP) Interface
The embedded Web Server application provides the user with an easy to use interface to
configure and monitor all aspects of the Base Modem. These web pages have been
designed for optimal performance when using Microsoft’s Internet Explorer 5.5 or
higher. By typing http://xxx.xxx.xxx.xxx” (where xxx.xxx.xxx.xxx =Base Modem IP
address) on your browser, the Login prompt will appear.

HTTP Login Access Levels are defined as follows:
User
Interface

Web

User Login Access Level
Read/Write User
Read Only User

Admin User

FULL ACCESS TO ALL WEB
PAGES

NO ACCESS TO ADMIN

PAGES

FULL ACCESS FOR ALL
OTHER WEB PAGES

VIEW ONLY ACCESS FOR
ALL OTHER WEB PAGES

Default Name/Passwords are:
•
•
•

Admin
Read/Write
Read Only

comtech/comtech
opcenter/1234
monitor/1234

11–2

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

11.3.1

Revision 5
MN/CDMQx.IOM

Web Server Menu Tree
Table 12-1. Web Server Menu Tree
Level 2

Level 1
Home

Home
Contact
Support

Admin

Access
Remote

Config Mdm

Quick View
Unit Status

Maint

Unit Info

Please make sure that the web browser does not use the old cached web page
once you visited the same page.
IMPORTANT

11–3

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

To see the installed cards in the chassis, click Quick View under Config Mdm. It should
be noted that the user needs to wait for the whole page to display, that is, the left-hand
side of the page should display at least the word Base. An example is shown below:

As shown on the left-hand side of the web page, the CDM-Qx has two Tx cards and two
Rx cards (one Tx and one Rx grouped as modem, and the others are individual Tx and
Rx). In this page, the Base is highlighted, that means the current page that is being
displayed belongs to the Base. At the center of this page, the sub-menu Config, Status,
Test, Utility, allows the user to navigate the Base configuration, status, test, and utilities.
For this example, Config is highlighted which means Base configuration. The word Base
is being used to designate the common and grouped functions of the installed cards (Tx
or Rx).
To see the configuration of the cards which are grouped as modem, just mouse click MD
icon (single click only). Clicking any of these icons will be highlighted. As will be shown
in the next example is the configuration of the cards grouped as modem.

11–4

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

As you can see the MD icon is highlighted as well as the Config. In this case, both the
modulator and demodulator parameters are accessible.
If TX icon is selected, only the modulator parameters will be displayed and accessible. If
RX icon is selected, only the demodulator parameters will be displayed and accessible.

11–5

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

Using the web browser, the user can view the constellation of the demodulated signal as
shown below:

In this example, the CDM-Qx has four (4) Rx cards installed. Clicking the Base and then
Test, will allow the user to view all the constellations of all the demodulators at once.
The user can also view one constellation at a time by just selecting one RX only.

11–6

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

Since the introduction of the spectrum analyzer feature in the CDM-Qx, the user can
view the spectrum of the signal as shown below:

When the spectrum analyzer feature is turned ON, the demodulator handling this will not be allowed
to receive traffic and built-in BERT monitor is ignored. It should be noted the web page only captures
the spectrum.

11–7

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

11.4

Revision 5
MN/CDMQx.IOM

SNMP Interface
The Simple Network Management Protocol (SNMP) is an application-layer protocol
designed to facilitate the exchange of management information between network devices.
The CDM-Qx SNMP agent supports both SNMPv1 and v2c.

IMPORTANT

11.4.1

For proper SNMP operation, the CDM-Qx MIB files must be used with the
associated version of the CDM-Qx base modem M&C. Please refer to the CDM-Qx
SW Release Notes for information on the required FW/SW compatibility.

Management Information Base (MIB) Files
MIB files are used for SNMP remote management and consist of Object Identifiers
(OIDs). Each OID is a node that provides remote management of a particular function. A
MIB file is a tree of nodes that is unique to a particular device.
There are three MIB files associated with the CDM-Qx:
MIB File/Name
fw10874-2-.mib
ComtechEFData
MIB file

fw11247-1- .mib
CDM-Qx
MIB file
fw11247-2- .mib
CDM-Qx Traps
MIB file

Description
ComtechEFData MIB file gives the root tree for ALL Comtech EF Data
products and consists of only the following OID:
Name: comtechEFData
Type: MODULE-IDENTITY
OID: 1.3.6.1.4.1.6247
Full
path: iso(1).org(3).dod(6).internet(1).private(4).enterprises(1).comtechEFD
ata(6247)
Module: ComtechEFData
MIB file consists of all of the OIDs for management of the modem functions

Trap MIB file is provided for SNMPv1 traps common for base modems.

These MIB files should be compiled in a MIB Browser or SNMP Network Monitoring
System server.
Note: The SNMP agent supports both “SNMPv1” and “v2c”. The “Traps” file only
needs to be compiled if “SNMPv1” traps are to be used.

11–8

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

11.4.2

Revision 5
MN/CDMQx.IOM

SNMP Community Strings
The modem uses community strings as a password scheme that provides authentication
before gaining access to the modem agent’s MIBs.
In “SNMP v1/v2c”, the community string is sent unencrypted in the SNMP packets.
Caution must be taken by the network administrator to ensure that SNMP packets travel
only over a secure and private network if security is a concern. A packet sniffer can
easily obtain the community string by viewing the SNMP traffic on the network.
The community string is entered into the MIB Browser or Network Node Management
software and is used to authenticate users and determine access privileges to the SNMP
agent.
The user defines three Community Strings for SNMP access:
•
•
•

11.4.3

Read Community
Write Community
Trap Community

default = public
default = private
default = comtech

SNMP Traps
The modem has the ability to send out SNMP traps when certain events occur in the
modem. The modem sends out traps when an alarm or a fault occurs in the modem.
These include unit faults, TX faults, RX faults, and ODU faults. A trap is sent both when
a fault occurs and is cleared.
The modem supports both SNMPv1 traps and SNMPv2 notifications. The user using the
cdmQxSNMPTrapVersion OID can configure which style of traps the modem sends.
The following are the MIB2 v1traps/v2 notifications that the modem supports:
MIB2 SNMPv1 trap: Authentication Failure 5
MIB2 SNMPv2 notifications: Authentication Failure

11–9

1.3.6.1.6.3.1.1.5.5

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

The following tables are the Alarms and Faults v1 traps / v2 notifications that the modem
supports.
Alarms and Faults SNMPv1 traps:\
CdmQxTxTrafficAlarmV2

6247272

CdmQxUnitAlarmV2

6247271

CdmQxRxTrafficAlarmV2

6247273

Alarms and Faults SNMPv2 notifications:

11.5

CdmQxUnitAlarmV2

1.3.6.1.4.1.6247.27.2.0.1

CdmQxTxTrafficAlarmV2

1.3.6.1.4.1.6247.27.2.0.2

CdmQxRxTrafficAlarmV2

1.3.6.1.4.1.6247.27.2.0.3

Telnet Interface
The modem provides a Telnet interface for two primary functions:
•
•

Equipment M&C via the standard equipment Remote Control protocol.
Equipment M&C via Comtech Monitor and Control System (CMCS) application.

The Telnet interface requires user login at the Administrator level and Read/Write
level.
The screen capture below shows the login process.

11–10

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

Once logged into the Telnet interface as the Administrator, the user can access the
standard remote control interface defined in Appendix C as shown in the example below:

11–11

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

There is a disadvantage when using Windows DOS as Telnet Client. Since Windows
DOS cannot translate a ‘\r’ to a ‘\r\n’ for the messages coming from Telnet Server, the
multi-line command response (for example, FRW? Response) will be displayed as one
line, with the latter lines overwrite the previous lines.
In order to view the full response messages, we recommend using HyperTerminal
configured as Telnet Client. To do so, configure the HyperTerminal as following:
1. Connect using TCP/IP instead of COM1 or COM2;
2. ASCII setup: check both "Send line ends with line feeds" and "Append line feeds to

incoming line ends" options.
See the following screen captures for examples.

11–12

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

11–13

CDM-Qx Satellite Modem
Ethernet Management (Base Modem)

Revision 5
MN/CDMQx.IOM

11–14

Appendix A. SUMMARY OF
SPECIFICATIONS

A.1

Modulator
Note: Features not in the initial product release are identified in parentheses.

Modulation
Symbol rate range
Data rate range
Operating modes
FEC
Transmit filtering
Scrambling
Output frequency

External Reference
Harmonics
and spurious

Transmit On/Off
Ratio
Output phase noise
Output power

Power accuracy

See Table A-5
Up to 10 Msps (lower end is modulation and FEC rate dependant)
Refer to Figure A-1.
See Table A-5
Transparent, closed network, DoubleTalk™ Carrier-in-Carrier®
See Table A-5
Per INTELSAT IESS-308 (0.35) or 0.20 (for use with closer adjacent channel spacing)
V.35 or synchronous
50 to 90, 100 - 180 MHz, 100 Hz resolution (70/140 MHz IF)
950 to 1950 MHz, 100 Hz resolution (L-Band)
Stability ± 1 ppm, 0 to 50oC (32 o to 122 oF) (standard low-stability internal reference)
o
o
o
Stability ± 0.1 ppm, 0 to 50 C (32 to 122 F) (Optional high-stability internal reference)
Stability ± 0.1 ppm, 0 to 50oC (32 o to 122 oF) (standard reference for L-Band)
1, 2, 5, 10, or 20 MHz @ 0 dBm to +20 dBm. Internal reference phase locks to external
reference.
Greater than -55 dBc/4 kHz (typically <-60 dBC/4kHz) – measured from 25 to 400 MHz
(70/140MHz IF)
Greater than -55 dBc/4 kHz (typically <-60 dBC/4kHz) – measured from 500 to 2500 MHz
(L-Band)
Spurious measured relative to an unmodulated (CW) carrier
55 dB minimum
< 0.480rms double sided, 100 Hz to 1MHz
(minimum of 10 dB better overall than the INTELSAT IESS-308/309 requirement)
-5 to -25 dBm, 0.1 dB steps (70/140MHz IF)
-5 to -45 dBm, 0.1 dB steps (L-Band).
Refer to Automatic Uplink Power Control section.
±1.0 dB over frequency, temperature, and number of modulators installed in the chassis

A–1

CDM-Qx Satellite Modem
Summary of Specifications

Output Connector
Output Return Loss
Clocking Options

External TX
Carrier Off

0.00

0.10

Revision 5
MN/CDMQx.IOM

Type BNC Female (70/140MHz IF)
Type N Female (L-Band)
≥ 19 dB (70/140MHz IF)
≥ 10 dB (L-Band)
Internal, ±1ppm or 0.1 ppm (SCT)
External, locking over a ±100 ppm range (TT)
Loop timing (Rx satellite clock) - supports asymmetric operation - Rx and Tx data rates do not
need to be identical
External Clock at transmit data rate.
By TTL 'low' signal or external contact closure - hardware function automatically over-rides
processor

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

1.20

-5

-10

1.40

Symbol Rate, Rs

Comtech EF Data
CDM-Qx Transmit
Power Spectral Density,
referred to symbol rate

-15

-20

-25

-30

-35

Intelsat
IESS 308/309
Limit

-40
CDM-Qx Modulator
typically < -50 dB, and
guaranteed to be
< -45 dB at offsets
> 0.75 Rs

-45

-50

1.30

Spectral
density,
dB

Intelsat
IESS 308/309
Limit

-55

Figure A-1. Power Spectral Density Chart

A–2

1.50

CDM-Qx Satellite Modem
Summary of Specifications

A.2

Revision 5
MN/CDMQx.IOM

Demodulator
FEC, Data rate range, operating modes, descrambling, input impedance/return loss etc, as
per Modulator

Input power range
(70/140MHz IF)
Input power range
(L-Band)
Acquisition range
Acquisition time
Clock tracking range
VITERBI
BER performance
(met in the presence
of two adjacent
carriers, each 7 dB
higher than the
desired carrier)

VITERBI and RS
220,200 or 200,180
Outer Code BER
(with two adjacent
carriers, each 7 dB
higher than the
desired carrier)

-15 to -45 dBm, < 2.048 Msps (desired carrier)
-15 to -40 dBm, > 2.048 and < 4.096 Msps (desired carrier)
-15 to -35 dBm > 4.096 Msps (desired carrier)
+35 dBc maximum composite, up to -5 dBm
-130 + 10log(Symbol Rate in Hz) minimum signal level
50dB AGC range
±1 to ±32 kHz, programmable in 1kHz increments (below 64 ksps, ± symbol rate/2) (70/140)
±1 to ± (symbol rate/2) kHz up to ± 200kHz (L-Band)
Highly dependent on data rate, FEC rate, and demodulator acquisition range.
Note that Reed-Solomon increases acquisition time, due to the additional time taken for the
RS decoder to declare synchronization.
± 100 ppm min
Rate 1/2 (B, Q)
Rate 3/4 (Q)
Rate 7/8 (Q)
Guaranteed Eb/No:
Guaranteed Eb/No:
Guaranteed Eb/No:
(typical value in
(typical value in
(typical value in
parentheses)
parentheses)
parentheses)
For:
-5
5.4 dB (4.9 dB)
6.8 dB (6.3 dB)
7.7 dB (7.2 dB)
BER=10
BER=10-6

6.0 dB (5.5 dB)

7.4 dB (6.9 dB)

8.4 dB (7.9 dB)

BER=10-7

6.7 dB (6.2 dB)

8.2 dB (7.7 dB)

9.0 dB (8.6 dB)

Rate 1/2 (B, Q)
Guaranteed Eb/No:
(typical value in
parentheses)

Rate 3/4 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)

Rate 7/8 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)

For:
BER=10-5

4.3 dB (4.0 dB)

5.6 dB (4.7 dB)

6.5 dB (6.0 dB)

BER=10-6

4.4 dB (4.1 dB)

5.8 dB (4.8 dB)

6.7 dB (6.2 dB)

4.5 dB (4.2 dB)
Rate 2/3 8-PSK/TCM
Guaranteed Eb/No:
(typical value in
parentheses)

6.0 dB (5.2 dB)
Rate 2/3 8-PSK/TCM
w/concatenated RS
Guaranteed Eb/No:
(typical value in
parentheses)

6.9 dB (6.5 dB)

BER=10-5

7.9 dB (7.2 dB)

6.3 dB (5.4 dB)

BER=10-7

9.5 dB (8.7 dB)

6.7 dB (5.8 dB)

BER=10-8

10.4 dB (9.5dB)
Rate 1/2 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)

6.9 dB (6.0 dB)
Rate 21/44 (B)
Guaranteed Eb/No:
(typical value in
parentheses)

Rate 5/16 (B)
Guaranteed Eb/No:
(typical value in
parentheses)

2.9 dB (2.6 dB)

2.8 dB (2.5dB)

2.4 dB (2.1dB)

-7

BER=10
8-PSK/TCM CODEC
BER
(With two adjacent
carriers, each 7 dB
higher than the
desired carrier)

TURBO PRODUCT
CODEC
Rate 1/2 QPSK
Rate 21/44 BPSK
Rate 5/16 BPSK
BER

For:

For:
-6

BER=10

A–3

CDM-Qx Satellite Modem
Summary of Specifications

(With two adjacent
carriers, each 7 dB
higher than the
desired carrier)
TURBO PRODUCT
CODEC
Rate 3/4 QPSK
Rate 3/4 8-PSK
Rate 3/4 16-QAM
BER
(With two adjacent
carriers, each 7 dB
higher than the
desired carrier)
TURBO PRODUCT
CODEC
Rate 7/8 QPSK
Rate 7/8 8-PSK
Rate 7/8 16-QAM
BER
(With two adjacent
carriers, each 7 dB
higher than the
desired carrier)
TURBO PRODUCT
CODEC
Rate 17/18 QPSK
Rate 17/18 8-PSK
BER
(With two adjacent
carriers, each 7 dB
higher than the
desired carrier)
HIGHER-ORDER
MODULATION AND
CODING
(With two adjacent
carriers, each 7 dB
higher than the
desired carrier)
Plesiochronous/
Doppler Buffer

Monitor Functions

Revision 5
MN/CDMQx.IOM

-7

3.1 dB (2.7 dB)

-8

3.3 dB (2.8 dB)
Rate 3/4 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)

BER=10

-6

3.8dB (3.4dB)

6.2 dB (5.8 dB)

7.4dB (7.0 dB)

BER=10-7

4.1dB (3.7dB)

6.4 dB (6.0 dB)

7.8 dB (7.3 dB)

4.4dB (4.0dB)
Rate 7/8 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)

6.8 dB (6.3 dB)
Rate 7/8 (8-PSK)
Guaranteed Eb/No:
(typical value in
parentheses)

8.2 dB (7.7 dB)
Rate 7/8 (16-QAM)
Guaranteed Eb/No:
(typical value in
parentheses)

BER=10-6

4.3 dB (4.0 dB)

7.3 dB (6.6 dB)

8.1 dB (7.7 dB)

BER=10-7

4.4 dB (4.1 dB)

7.4 dB (6.7 dB)

8.2 dB (7.8 dB)

BER=10
BER=10

For:

-8

BER=10

For:

3.1 dB (2.8 dB)
3.3 dB (2.90dB)
Rate 3/4 (8-PSK)
Guaranteed Eb/No:
(typical value in
parentheses)

-8

4.5 dB (4.2 dB)
Rate 17/18 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)

7.5 dB (6.8 dB)
Rate 17/18 (8-PSK)
Guaranteed Eb/No:
(typical value in
parentheses)

BER=10

-6

6.4 dB (6.0 dB)

9.3 dB (8.9 dB)

BER=10-7

6.7 dB (6.3 dB)

9.8 dB (9.4 dB)

BER=10-8

6.9 dB (6.5 dB)
16-QAM Rate 3/4
Viterbi/RS
Guaranteed Eb/No:
(typical value in
parentheses)

10.3 dB (9.9 dB)
16-QAM Rate 7/8
Viterbi/RS
Guaranteed Eb/No:
(typical value in
parentheses)

8.1 dB (7.5 dB)

9.5 dB (9.0 dB)

BER=10

For:

For:
-6

BER=10

2.6 dB (2.3dB)
2.7 dB (2.4dB)
Rate 3/4 (16-QAM)
Guaranteed Eb/No:
(typical value in
parentheses)

8.3 dB (7.9 dB)

10.1 dB (9.5 dB)
8.6 dB (8.0 dB)
BER=10-8
Selectable size of 1024, 2048, 4096, 8192, 16384 and 32768 bits
Size selection is displayed in bytes and milliseconds
Supports asymmetric operation - when buffer is clocked from Tx clock, Rx and Tx rates do not
need to be identical
Eb/No estimate, 2 to 16 dB (± 0.10 dB accuracy)
Corrected Bit Error Rate, 1E-3 to 1E-10
Frequency offset, ± 32 kHz range, 100 Hz resolution (70/140 MHz IF)
Frequency offset, ± 200 kHz range, 100 Hz resolution (L-Band)
Buffer fill state, in percent
Receive signal level accuracy = ± 3.0 dB)

A–4

CDM-Qx Satellite Modem
Summary of Specifications

A.3

Revision 5
MN/CDMQx.IOM

Data Interfaces
Note: Features not in the initial product release are identified in parentheses.

EIA-530

Synchronous RS-232

EIA-530
(3 selectable modes)

EIA-422/EIA-530 DCE (Rates up to 12 Mbps)
Also supports X.21
V.35 DCE (Rates up to 12 Mbps)
Synchronous RS-232 (Rates up to 300 kbps)

25-pin D-sub (female)

G.703 (Balanced)

1.544 Mbps T1 (Balanced 100 Ω)
2.048 Mbps E1 (balanced 120 Ω)

15-pin D-sub (female)

G.703 (Unbalanced)

1.544 Mbps T1 (unbalanced 75 Ω)
2.048 Mbps E1 (unbalanced 75 Ω)

BNC (female)

Multi-Port G.703 (Bal)
1 to 4 Ports E1 w/ D&I

2.048 Mbps E1 (balanced 120 Ω)
Note: All 4 ports must be synchronous

(2) 9-pin, D-sub (female)
(2 ports per DB-9)

EIA-612 / 613
(HSSI)

EIA-612/EIA-613 (Rates up to 20 Mbps)

50-pin, mini-D SCSI-II
HSSI (female)

Modem Alarms
(Present on all modules)

Relay outputs (Tx, Rx & unit faults)
Demodulator I & Q test outputs (constellation)
Demodulator Rx Signal Level output (0 to 2.5 volts)
External carrier off input
EIA-232 or EIA-485 modem control and monitoring
IP based monitoring & control

15-pin D-sub (male)

Serial Remote Control
10/100BaseT

A.4

9-pin D-sub (male)
RJ-45

Automatic Uplink Power Control (Future)

Operating Mode
Target Eb/No range
Max AUPC range
Monitor functions

Requires Closed Network Framed mode for transport of Eb/No information from remote
modem (EDMAC can be enabled or disabled)
0 to 9.9 dB at remote demod (default is 4.0 dB)
0 to 9 dB (default is 3 dB)
Remote demod Eb/No
Tx power level increase
(front panel or via remote control interface)

A–5

CDM-Qx Satellite Modem
Summary of Specifications

A.5

Revision 5
MN/CDMQx.IOM

Data Rate Ranges
FEC Type

Modulation

Code Rate

Viterbi
Viterbi
Viterbi
Viterbi
Viterbi + R-S
Viterbi + R-S
Viterbi + R-S
Viterbi + R-S
Viterbi + R-S
Viterbi + R-S
TCM + RS
TPC
TPC
TPC
TPC
TPC
TPC
TPC
TPC
TPC
TPC
TPC

BPSK
QPSK
QPSK
QPSK
BPSK
QPSK
QPSK
QPSK
16-QAM
16-QAM
8-PSK
BPSK
BPSK
QPSK
QPSK
QPSK
QPSK
8-PSK
8-PSK
8-PSK
16-QAM
16-QAM

Rate 1/2
Rate 1/2
Rate 3/4
Rate 7/8
Rate 1/2
Rate 1/2
Rate 3/4
Rate 7/8
Rate 3/4
Rate 7/8
Rate 2/3
Rate 5/16
Rate 21/44
Rate 21/44
Rate 3/4
Rate 7/8
Rate 17/18
Rate 3/4
Rate 7/8
Rate 17/18
Rate 3/4
Rate 7/8

A–6

Data Rate Range
32 kbps to 5 Mbps
32 kbps to 10 Mbps
32 kbps to 15 Mbps
32 kbps to 17.5 Mbps
32 kbps to 4.5 Mbps
32 kbps to 9.1 Mbps
32 kbps to 13.7 Mbps
32 kbps to 16 Mbps
349.1 kbps to 20 Mbps
407.3 kbps to 20 Mbps
232.7 kbps to 18.3 Mbps
32 kbps to 3.1 Mbps
32 kbps to 4.7 Mbps
32 kbps to 9.5 Mbps
32 kbps to 15 Mbps
32 kbps to 17.5 Mbps
32 kbps to 18.888 Mbps
288 kbps to 20 Mbps
336 kbps to 20 Mbps
362 kbps to 20 Mbps
384 kbps to 20 Mbps
448 kbps to 20 Mbps

CDM-Qx Satellite Modem
Summary of Specifications

A.6

Revision 5
MN/CDMQx.IOM

Framing Summary (Future)
Overhead
added

Transparent
None

Available
data rates
and format
Overhead
components

All rates and
formats

Additional
ReedSolomon
Overhead
Scrambling
(see Note 1 )

220/200
225/205
219/201 for
IESS-310 mode
Basic ITU
V.35 (Intelsat)

None

EDMAC (Future)
5% to 2 Mbps
1.5%
(see Note 2)
All rates and formats
Remote control link
between modems’
processor
200/180

Proprietary
scrambler

Notes:
1. When Reed-Solomon is Off.
2. 1.5 % for Rates 5/16, 21/44 BPSK Turbo, Rate 21/44 QPSK Turbo,
and all rates > 2 Mbps

A.7

Miscellaneous

Front panel
Loopbacks
Fault relays
M&C Interface
M&C Software
AC Consumption
AC Operating Voltage
DC Operating Voltage
Temperature:
Operating
Storage
Dimensions
Weight
CE Mark
FCC

Tactile keypad, 6 keys (Up/Down, Left/Right, Enter/Clear)
Vacuum Fluorescent Display (blue) - 2 lines of 40 characters
Internal IF loopback, RF loopback, digital loopback, and inward/outward loopback
Hardware fault, RX and TX Traffic Alarms
EIA-232 and EIA-485 (addressable multidrop, 2-wire or 4-wire), 10/100 BaseT Ethernet
SATMAC software for control of local and distant units
(Depends on configuration) 60 watts (maximum)
100 to 240 VAC, +6%/-10% - autosensing
(total absolute max. range is 90 to 254 VAC)
36 to 72 VDC, 6.25 amps
0 to 50oC (32 to 122oF)
o
o
-25 to 85 C (-13 to 185 F)
1.75H x 19W x 19D inches
(4.4H x 48W x 48D cm)
< 20 lbs (7.0 kg) approx (depends on configuration)
EMC Safety
Part 15

A–7

CDM-Qx Satellite Modem
Summary of Specifications

Revision 5
MN/CDMQx.IOM

Notes:

Appendix B. FLASH UPGRADING
The modem eliminates the need for updating firmware by physically replacing EPROMs.
Instead, the modem uses ‘flash memory’ technology internally, and new firmware can be
uploaded to the unit from an external PC, as follows:
Go to: www.comtechefdata.com
Click on: downloads
Click on: flash upgrades
This makes software upgrading very simple, and updates can now be sent via the Internet,
E-mail, or on disk. The upgrade can be performed without opening the unit, by simply
connecting the modem to the USB or Ethernet port of a computer.

B.1

Ethernet FTP upload procedure:
1. Identify the reflashable product, firmware number, and version for download.
The current base modem M&C version can be viewed at the top-level menu of
the front panel display (press “CLR” button several times to view). Also, you can
find the firmware information within the menu tree.
Using serial remote control, you can query the firmware revision levels with the
<0/SWR? Command. (Abbreviated)
Or
<0/FRW? Command (Detailed)
2. Create a temporary directory (folder) on your PC.
Windows: Select File > New > Folder > and rename the New Folder to "temp" or
another convenient and unused name. Assuming "temp" works, you should now
have a "c:\temp" folder created.
Note: The c: is the drive letter used in this example. Any valid writable drive
letter can be used.

B–1

CDM-Qx Satellite Modem
Flash Upgrading

Revision 5
MN/CDMQx.IOM

Alternate Method: CMD Prompt: At the command prompt (c:\>) type "MD
temp" without quotes (MD stands for make directory). This is the same as
creating a new folder from Windows. You should now have a "c:\temp"
subdirectory created where c: is the drive letter used in the example.
3. Download the correct firmware file to this temporary folder. (Procedure is Under
Construction.)
Access the download server with the flash firmware data files link,
http://206.223.8.10/linksite/flashupgrades/CDMQx/
About Firmware Numbers, File Versions, and Formats:
The flashable files on the download server are organized by product first, then by
firmware number, (make sure you know the correct firmware number; see step 1)
version, if applicable, and release date. The base modem bulk firmware for the
CDM-Qx will be F11245*_*_* (where the asterisks show revision, version and
date).
The current version firmware release is provided. If applicable, one version prior
to the current release is also available. Be sure to identify and download the
desired version.
The downloadable files are stored in two formats: *.exe (self extracting) and
*.zip (compressed).
Some firewalls will not allow the downloading of *.exe files. In this case,
download the *.zip file instead.
For additional help with "zipped" file types, refer to "pkzip for windows",
"winzip", or "zip central" help files. Pkzip for DOS is not supported due to file
naming conventions.
4. Unzip the files in the temporary folder on your PC.
At least 3 files should be extracted:
a. FW11245x.bin, where "x" is the revision (bulk image file)
b. QxReleaseNotes_x.pdf, where "x" is the version (release notes)
c. README_X.TXT, where “X” is the version (installation notes)
5. Connect the client PC to the CDM-Qx modem 10/100 Ethernet M&C via a hub or a
switch, or directly to a PC with a crossover cable.

Base modem firmware can be loaded via the Ethernet M&C port.
IMPORTANT

B–2

CDM-Qx Satellite Modem
Flash Upgrading

Revision 5
MN/CDMQx.IOM

Verify the communication and connection by issuing a "ping" command to the
modem. You can find the IP address of the modem either remotely using the
<0/IPA? command or from the front panel with the
menus.
To PING and FTP from DOS, press the “Start” button on the Windows toolbar,
and select the “Run...” option.
• From Win95 or Win98, type “command”.
• From WinNT, Win2K or WinXP, type “cmd”.
• You can also use the “DOS Prompt” or “Command Prompt” icons in the
Start Menu.
• Now change to the temporary directory you created earlier with
“cd c:\temp”.
• A quick “dir” will show the downloaded files.
6. Initiate an FTP session with the modem. The example is with a DOS window.
a. From the PC, type "ftp xxx.xxx.xxx.xxx" where "xxx.xxx.xxx.xxx" is the
IP address of the CDM-QXx .
b. Enter your admin user name and password to complete login.
c. Verify your FTP transfer is binary by typing "bin".
d. Type "prompt" then type "hash" to facilitate the file transfers.
7. Transfer the files.
Type "put c:\temp\FW11245*.bin bulk:" to begin the file transfers. The
destination “bulk:” must be all lower-case. It will take approximately
1 minute to transfer the file.
8. Verify the file transfer.
a.

The PC should report that the file transfer has occurred, and the display on the
modem will stop reporting:

SECTOR
NO. XXX

REFLASHING..........

PLEASE WAIT

[

]

b. Terminate the FTP session by typing "bye" and closing the DOS window.
c. Verify that the new file loaded using the procedure in step 1.
9. Change the desired image to boot using the