Comtech EF Data CDM-500 User Manual

p

CDM-500

Satellite Modem

Installation and O

eration Manual

Part Number MN/CDM500.IOM Revision 1.3

Comtech EFData is an ISO 9001

Registered Company.

CDM-500

Satellite Modem

Installation and Operation Manual

Part Number MN/CDM500.IOM

Revision 1.3

July 10, 2000

Copyright © Comtech EFData, 2000. All rights reserved. Printed in the USA.

Comtech EFData, 2114 West 7th Street, Tempe, Arizona 85281 USA, [phone], FAX: [phone].

Customer Support

Contact the Comtech EFData Customer Support Department for:

• Product support or training

• Information on upgrading or returning a product

• Reporting comments or suggestions concerning manuals

A Customer Support representative may be reached at:

Comtech EFData
Attention: Customer Support Department
2114 West 7th Street
Tempe, Arizona 85281 USA

[phone] (Main Comtech EFData Number)
[phone] (Customer Support Desk)
[phone] FAX

or, E-Mail can be sent to the Customer Support Department at:

[e-mail]

Contact us via the web at www.comtechefdata.com

1. To return a Comtech EFData product (in-warranty and out-of-warranty) for
repair or replacement:

2. Request a Return Material Authorization (RMA) number from the Comtech
EFData Customer Support Department.

3. Be prepared to supply the Customer Support representative with the model
number, serial number, and a description of the problem.

4. To ensure that the product is not damaged during shipping, pack the product in
its original shipping carton/packaging.

5. Ship the product back to Comtech EFData. (Shipping charges should be prepaid.)

For more information regarding the warranty policies, see Error! Reference source not
found., p. Error! Bookmark not defined..

.

Comtech EFData, 2114 West 7th Street, Tempe, Arizona 85281 USA, [phone], FAX: [phone].

Copyright © Comtech EFData, 2000. All rights reserved. Printed in the USA.

CDM-500 Satellite Modem Preface

Table of Contents

Customer Support........................................................................................................................................................ i

About this Manual ....................................................................................................................................................vii

Conventions and References...................................................................................................................................vii

Cautions and Warnings......................................................................................................................................vii

Metric Conversion..............................................................................................................................................vii

Reporting Comments or Suggestions Concerning this Manual..............................................................................vii

SAFETY NOTICES................................................................................................................................................. viii

Electrical Safety.....................................................................................................................................................viii

Fuses......................................................................................................................................................................viii

Environmental.......................................................................................................................................................... viii

Installation..................................................................................................................................................................ix

Telecommunications Terminal Equipment Directive............................................................................................. ix

EMC (Electromagnetic Compatibility).................................................................................................................... ix

Warranty Policy.......................................................................................................................................................... x

Limitations of Warranty ........................................................................................................................................... x

Exclusive Remedies.................................................................................................................................................. x

CHAPTER 1.

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

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

CHAPTER 2.

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

2.1 Mounting.......................................................................................................................................................2–1

Rev. 1.3 i

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

Preface CDM-500 Satellite Modem

2.2 Configuration................................................................................................................................................ 2–2

2.3 Select Internal IF Loop................................................................................................................................ 2–2

2.4 Connect External Cables ............................................................................................................................. 2–2

CHAPTER 3.

3.0 Functional Description................................................................................................................................. 3–1

CHAPTER 4.

4.1 Front Panel ................................................................................................................................................... 4–1

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

CHAPTER 5.

5.1 Connector Pinouts........................................................................................................................................ 5–1

5.1.1 Data Connector - 25 Pin ‘D’ Type Female..............................................................................................5–1

5.2 Alarms Connector - 15 Pin ‘D’ Type Male................................................................................................. 5–2

FUNCTION..........................................................................................3–1

PHYSICAL DESCRIPTION.................................................................4–1

CONNECTOR PINOUTS.....................................................................5–1

5.3 Remote Control Connector - 9 Pin ‘D’ Type Male................................................................................. ... 5–3

5.4 Auxiliary Serial Connector - He1402 3 Pin Header .................................................................................. 5–3

CHAPTER 6.

6.1 Description.................................................................................................................................................... 6–1

6.2 Menu Trees................................................................................................................................................... 6–3

6.3 OPENING SCREEN.................................................................................................................................... 6–4

6.4 SELECT........................................................................................................................................................ 6–4

6.5 CONFIG: ...................................................................................................................................................... 6–5

6.5.1 (CONFIG) TX (Transmit)...................................................................................................................... 6–5

6.5.2 (CONFIG, TX) MOD (Modulation)....................................................................................................... 6–6

6.5.3 (CONFIG, TX) FREQ (Frequency)........................................................................................................ 6–6

6.5.4 (CONFIG, TX) DATA (Data Rate)........................................................................................................ 6–6

6.5.5 (CONFIG, TX) FEC (Forward Error Correction)...................................................................................6–6

6.5.6 (CONFIG, TX) ON/OFF........................................................................................................................ 6–6

6.5.7 (CONFIG, TX) PWR (Power)................................................................................................................ 6–7

6.5.8 (CONFIG, TX) SCRAM (Scrambling) .................................................................................................. 6–7

6.5.9 (CONFIG, TX) CLK (Clocking)............................................................................................................6–7

6.5.10 (CONFIG, TX) TSI (Transmit Spectral Invert) ................................................................................6–7

6.5.11 (CONFIG) RX (Receive)................................................................................................................... 6–8

6.5.12 (CONFIG, RX) MOD (Modulation).................................................................................................. 6–8

6.5.13 (CONFIG, RX) FRQ (Frequency)......................................................................................................6–8

FRONT PANEL OPERATION.............................................................6–1

ii Rev. 1.3

CDM-500 Satellite Modem Preface

6.5.14 (CONFIG, RX) DATA (Data Rate)................................................................................................... 6–8

6.5.15 (CONFIG, RX) FEC (Forward Error Correction).............................................................................. 6–8

6.5.16 (CONFIG, RX) ACQ (Acquisition sweep range) .............................................................................. 6–9

6.5.17 (CONFIG, RX) DESCRAM (Descrambler).......................................................................................6–9

6.5.18 (CONFIG, RX) CLK (Clocking).........................................................................................................6–9

6.5.19 (CONFIG, RX) BUF (Buffer size).................................................................................................... 6–10

6.5.20 (CONFIG, RX) RSI (Receive spectral inversion) ............................................................................. 6–10

6.5.21 (CONFIG, RX) Eb/No (Eb/No Alarm).............................................................................................6–10

6.5.22 (CONFIG) FRAME (Framing Mode)...............................................................................................6–10

6.5.23 (CONFIG, FRAME) TRANSPARENT............................................................................................6–10

6.5.24 (CONFIG, FRAME) FRAMED........................................................................................................6–11

6.5.25 (CONFIG, FRAME, FRAMED) EDMAC-ON.................................................................................6–11

6.5.26 (CONFIG, FRAME, FRAMED, ON) EDMAC MASTER............................................................... 6–11

6.5.27 (CONFIG, FRAME, FRAMED, ON) EDMAC SLAVE..................................................................6–12

6.5.28 (CONFIG) INTFC (Interface)...........................................................................................................6–12

6.5.29 (CONFIG) REMCONT (Remote control).........................................................................................6–12

6.5.30 (CONFIG, LOCAL) .......................................................................................................................... 6–12

6.5.31 (CONFIG, REMOTE).......................................................................................................................6–12

6.5.32 (CONFIG, REMOTE, BAUD)..........................................................................................................6–13

6.5.33 (CONFIG, REMOTE, INTFC) ......................................................................................................... 6–13

6.5.34 (CONFIG, REM, INTFC, ADDR) RS232 BUS ADDRESS...........................................................6–13

6.5.35 (CONFIG, REM, INTFC, ADDR) RS485 BUS ADDRESS:.......................................................... 6–13

6.5.36 (CONFIG) MASK (Alarm mask).....................................................................................................6–13

6.5.37 (CONFIG, MASK) AGC ................................................................................................................. 6–14

6.5.38 (CONFIG, MASK) Eb/No ................................................................................................................ 6–14

6.5.39 (CONFIG, MASK) RX-AIS .............................................................................................................6–14

6.5.40 (CONFIG, MASK) BUF-SLIP (Buffer slip)..................................................................................... 6–14

6.5.41 (CONFIG, MASK) TX-AIS.............................................................................................................. 6–15

6.5.42 (CONFIG) IMPED (IF impedance) ..................................................................................................6–15

6.6 TEST ........................................................................................................................................................... 6–16

6.7 INFO (Information)................................................................................................................................... 6–17

6.7.1 (INFO) ID (Circuit ID).......................................................................................................................... 6–17

6.7.2 (INFO) TX (Transmit information)....................................................................................................... 6–17

6.7.3 (INFO) RX (Receive information)........................................................................................................ 6–17

6.7.4 (INFO) BUFF (Buffer information)...................................................................................................... 6–18

6.7.5 (INFO) EDMAC (Framing and EDMAC information)......................................................................... 6–18

6.7.6 (INFO) REMCONT (Remote Control information).............................................................................. 6–18

6.7.7 (INFO) MASK (Alarm mask information)............................................................................................ 6–18

6.7.8 (INFO) MISC (Miscellaneous information).......................................................................................... 6–19

6.8 MONIT (Monitor)...................................................................................................................................... 6–20

6.8.1 (MONIT) ALARMS.............................................................................................................................. 6–20

6.8.2 (MON, ALARMS) UNIT (Unit alarms)................................................................................................ 6–20

6.8.3 (MON, ALARMS) RECEIVE (Receive alarms)................................................................................... 6–20

6.8.4 (MON, ALARMS) TRANSMIT (Transmit alarms).............................................................................. 6–20

6.8.5 (MONIT) STORED EVENTS............................................................................................................... 6–21

6.8.6 (MON, EVENTS) VIEW ......................................................................................................................6–21

6.8.7 (MONIT) RX-PARAMS (Receive Parameters).................................................................................... 6–22

6.9 STORE/LD (Store/Load)........................................................................................................................... 6–23

6.9.1 (STORE/LD) STORE............................................................................................................................ 6–23

6.9.2 (STO/LD) LOAD .................................................................................................................................. 6–23

Rev. 1.3 iii

Preface CDM-500 Satellite Modem

6.10 UTIL (Utility) ............................................................................................................................................. 6–25

6.10.1 (UTIL) SET-RTC (Set real-time clock)............................................................................................ 6–25

6.10.2 (UTIL) DISPLAY (Display brightness)............................................................................................ 6–25

6.10.3 (UTIL) MAN-1:1 (Manual 1:1 switchover)......................................................................................6–25

6.10.4 (UTIL) RECENTER-BUF (re-center buffer).................................................................................... 6–25

6.10.5 (UTIL) ID (Circuit ID)...................................................................................................................... 6–26

CHAPTER 7.

7.1 Transmit Clocking........................................................................................................................................ 7–1

7.1.1 Internal Clock.......................................................................................................................................... 7–1

7.1.2 External Clock......................................................................................................................................... 7–1

7.1.3 Loop-Timed............................................................................................................................................. 7–2

7.2 Receive Clocking .......................................................................................................................................... 7–2

7.2.1 Buffer Disabled ....................................................................................................................................... 7–2

7.2.2 Buffer Enabled, Rx=Tx........................................................................................................................... 7–2

7.2.3 Buffer Enabled, Rx<>Tx......................................................................................................................... 7–2

7.3 X.21 Notes..................................................................................................................................................... 7–2

CHAPTER 8.

8.1 Theory Of Operation ...................................................................................................................................8–1

CLOCKING .........................................................................................7–1

EDMAC CHANNEL.............................................................................8–1

8.2 M&C Connection ......................................................................................................................................... 8–2

8.3 Setup Summary............................................................................................................................................ 8–3

APPENDIX A.

A.1 Modulator.....................................................................................................................................................A–1

A.2 Demodulator.................................................................................................................................................A–2

A.3 Data Interfaces..............................................................................................................................................A–3

A.4 Miscellaneous................................................................................................................................................A–3

A.5 Approvals......................................................................................................................................................A–3

APPENDIX B.

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

B.2 EIA-485.........................................................................................................................................................B–1

B.3 EIA-232.........................................................................................................................................................B–2

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

REMOTE CONTROL..........................................................................B–1

B.4 Basic Protocol...............................................................................................................................................B–2

iv Rev. 1.3

CDM-500 Satellite Modem Preface

B.5 Packet Structure...........................................................................................................................................B–3

B.5.1
B.5.2
B.5.3
B.5.4
B.5.5
B.5.6

Start Of Packet .................................................................................................................................... B–3

Address................................................................................................................................................B–3

Instruction Code..................................................................................................................................B–4

Instruction Code Qualifier...................................................................................................................B–4

Message Arguments............................................................................................................................B–5

End Of Packet .....................................................................................................................................B–5

Rev. 1.3 v

Preface CDM-500 Satellite Modem

Figures

FIGURE 1-1 CDM500 PHOTO...............................................................................................................................1–1

FIGURE 4-1 FRONT AND BACK PANELS......................................................................................................... 4–2

FIGURE 6-1 PRINCIPLE MENU TREE................................................................................................................ 6–3

FIGURE A-1 BER VITERBI DECODING............................................................................................................ A–4

Tables

TABLE 4-1- FRONT PANEL LED INDICATORS ................................................................................................ 4–2

TABLE 5-1 25 PIN ‘D’ TYPE FEMALE................................................................................................................5–1

TABLE 5-2 ALARMS CONNECTOR.....................................................................................................................5–2

TABLE 5-3 REMOTE CONTROL CONNECTOR................................................................................................. 5–2

TABLE 5-4 AUXILIARY SERIAL CONNECTOR................................................................................................ 5–3

vi Rev. 1.3

CDM-500 Satellite Modem Preface

About this Manual

This manual provides installation and operation information for the Comtech EFData
CDM-500 satellite modem. This is a technical document intended for earth station
engineers, technicians, and operators responsible for the operation and maintenance of
the CDM-500.

Conventions and References

Cautions and Warnings

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

CAUTION

WARNING

unsafe practices or risks of property damage.

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

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.

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 EFData Customer Support
Department.

Rev. 1.3 vii

Preface CDM-500 Satellite Modem

SAFETY NOTICES

Electrical Safety

The CDM-500 VSAT Modem 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 - 240 volts AC. It has a
maximum power consumption of 25 watts, and draws a maximum of 250 mA.

The user should observe the following instructions:

Fuses

The CDM-500 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 230 volt AC operation, use T0.5A, 20mm fuses.
For 115 volt AC operation, use T1A fuses, 20mm fuses.

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

IMPORTANT INFORMATION - PLEASE READ

BEFORE INSTALLATION AND USE

Environmental

The CDM-500 must not be operated in an environment where the unit is:

• Exposed to extremes of temperature outside the ambient range 0 to 50 C, 0
precipitation, condensation, or humid atmospheres above 95% RH,

• Altitudes (un-pressurised) greater than 2000 metres, excessive dust or vibration,
flammable gases, corrosive or explosive atmospheres.

• Operation in vehicles or other transportable installations which 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 Rev. 1.3

CDM-500 Satellite Modem Preface

Installation

The installation and connection to the line supply must be made in compliance to local or
national wiring codes and regulations.

The CDM-500 is designed for connection to a power system that has separate earth, line
and neutral conductors. The equipment is not designed for connection to power system
which has no direct connection to earth.

The CDM-500 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 equiv alent
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.

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.

EMC (Electromagnetic Compatibility)

The CDM-500 VSAT Modem has been demonstrated, by independent testing, to comply
with the following standards:

Emissions: EN 55022 Class B - Limits and methods of measurement of radio

interference characteristics of Information Technology Equipment.

FCC Part 15 Class B

Immunity: EN 50082 Part 1 - Generic immunity standard, Part 1: Domestic,

commercial and light industrial environment.

In order that the Modem continues to comply with these standards, observe the following
instructions:

• Connections to the transmit and receive IF ports (BNC female connectors) should be
made using a good quality coaxial cable – for example RG58/U (50 ohm) or RG59/U
(75 ohm).

• All 'D' type connectors attached to the rear panel must have back-shells which provide
continuous metallic shielding. Cable with a continuous outer shield (either foil or
braid, or both) must be used, and the shield must be bonded to the back-shell.

• The equipment must be operated with its cover on at all times. If it becomes necessary
to remove the cover, the user should ensure that the cover is correctly re-fitted before
normal operation commences.

Rev. 1.3 ix

Preface CDM-500 Satellite Modem

Warranty Policy

This Comtech EFData 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
EFData 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
EFData and all related custom, taxes, tariffs, insurance, etc. Comtech EFData is
responsible for the freight charges only for return of the equipment from the factory to
the customer. Comtech EFData will return the equipment by the same method (i.e., Air,
Express, Surface) as the equipment was sent to Comtech EFData.

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 EFData.

No other warranty is expressed or implied. Comtech EFData 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
EFData 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 EFData 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 EFData reserves the
right to make chang es in the specifications of the products described in this m anual at any
time without notice and without obligation to notify any person of such changes.

If you have any questions regarding your equipment or the information in this manual,
please contact the Comtech EFData Customer Support Department.

x Rev. 1.3

1.0 Introduction

The CDM-500 (Figure 1-1) is a very low-cost C losed Netw ork Satellite Modem, intended
for VSAT applications. It offers variable data rates from 2.4 to 512kbps, in BPSK and
QPSK modes. It is extremely compact, being 1U high and 12 inches deep, and consumes
only 18 watts. It has a front panel VFD display and keypad for local configuration and
control, although it can be fully remote-controlled. For 1:1 applications the CDM-500 is
supported by a low-cost external switch, the CRS-100. For Hub applications, the CDM­500 is supported by a low-cost 1:N switch, the CRS-200. Its fast acquisition time makes
it attractive for both demand-assigned and fixed-assigned SCPC applications.

Chapter 1.

INTRODUCTION

1

Figure 1-1. CDM-550 Satellite Modem

Rev. 1.3 1–1

Introduction CDM-500 Closed Network Satellite Modem

The CDM-500 includes, as standard, a universal data interface which eliminates the need
to exchange interface cards for different applications. The interfaces offered include
RS422 (EIA530) DCE, V.35 DCE, synchronous RS232 DCE, and X.21 DTE and DCE.

The internal software is both powerful and flexible, and permits the user to store, and
then retrieve, up to 10 different modem configurations. The unit includes many test
modes and loopbacks for rapid verification of the correct functioning of the unit. Of
particular note is the IF loopback, which permits the user to perform a quick diagnostic
test without having to disturb external cabling. During the loopback, all of the receive
configuration parameters are temporarily changed to match those of the transmit side.
When normal operation is again selected, all of the previous values are restored.

A perennial problem is that of the IF port impedance. Whilst many users select the
universal standard of 50 ohms, there are many users who are still using 75 ohms. In the
past this has presented difficulties for the manufacturer, who has traditionally had to offer
both options. The CDM-500 eliminates this problem, by offering both impedances in the
same unit. The user simply selects from the front panel which impedance he wishes to
use.

In order to facilitate network management, the CDM-500 incorporates

EDMA

C, an
acronym for Embedded Distant-end Monitor And Control. In this mode, an additional 5%
overhead is combined with the traffic data, which permits M&C information to be added
(transparently to the user), allowing access to the distant-end modem.

This mode does not require any additional cabling at either the local or distant-end
Modems - access to EDMAC is via the standard M&C control port. Full monitor and
control is possible, and importantly, the on/off status of the carrier at the distant-end
carrier can be controlled.

The CDM-500 has been designed as a companion product for the Comtech EFData line
of RF Transceivers. As such, the Modem incorporates an FSK serial link which can be
activated on the Receive IF port, for the purpose of communicating with a Transceiver, if
connected. In this manner, a user may monitor, configure, and control the Transceiver,
using the front panel display and keypad of the Modem. The EDMAC channel may also
be used to convey M&C data to a Transceiver at the distant end of a satellite link, if it is
connected to a CDM-500.

1–2 Rev. 1.3

2.0 Unpacking

Inspect shipping containers for damage. If shipping containers are damaged, they should
be kept until the contents of the shipment have been carefully inspected and checked for
normal operation.

Remove the packing list from the outside of the shipping carton. Open the carton and
remove the contents, checking the contents against the packing list. Verify completeness
of the shipment and that the unit functions correctly. If damage is evident, contact the
carrier and Comtech immediately and submit a damage report. Be sure to keep all
shipping materials for the carrier's inspection.

If the unit needs to be returned to Comtech EFData, please use the original shipping
container.

Chapter 2.

INSTALLATION

2

2.1 Mounting

If the CDM-500 is to be mounted in a rack, ensure that there is adequate clearance for
ventilation. The CDM-500 does not include a cooling fan, so care must be taken that too
many units are not mounted on top of each other. The limit is four units, and then a blank
1U panel must be inserted to allow sufficient airflow around the units. 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.

Rev. 1.3 2–1

Installation CDM-500 Closed Network Satellite Modem

Note that the CDM-500 is very light - under 7 lbs (3.2 kgs), and very short – 12 ins (305
mm). For this reason, it has not been designed to have rack slides mounted to the side of
the chassis. However, Comtech recommends that some method of support within the rack
should be employed, such a rack shelves. If the user is any doubt, please consult the
factory.

2.2 Configuration

There are no internal jumpers to configure, no interface cards to install, and no other
options to install. 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 64 kbps, QPSK, Rate 1/2 configuration. Please refer to the ‘FRONT
PANEL OPERATION’ section for details on how to fully configure the unit for the
desired operating parameters.

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.

2.3 Select Internal IF Loop

Correct operation of the unit may be verified rapidly, without the need for
externally connected equipment. From the top level menu, select TEST, then IF
LOOP (refer to the ‘FRONT PANEL OPERATION’ section) 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.

2.4 Connect External Cables

Having verified correct operation in IF loop, the user should now enter his desired
configuration, and proceed to connect all external cables. If difficulties are experienced,
please call the factory for assistance.

Please note that the modulator gives an output power level in the range 0 to –20 dBm,
and the demodulator expects to see a signal in the range -30 to -60 dBm.

2–2 Rev. 1.3

3

3.0 Functional Description

The CDM-500 has two fundamentally different types of interface - IF and data. The data
interface is 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 bi­directional 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 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
differentially encoded, scrambled, 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 QPSK/BPSK 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.

The received IF signal is first translated to a fixed IF frequency, using a frequency
synthesizer. An AGC circuit maintains the composite level within the IF bandwidth
constant over a limited range. Following this, the signal is sampled by a high-speed
(flash) A/D converter. All processing beyond this conversion is purely digital. The signal
is translated down to near zero frequency by a complex mix, and then is processed by a
digital Costas Loop, which performs the functions of Nyquist filtering, carrier recovery,
and bit-timing recovery. The resultant demodulated signal is fed, in soft decision form, to
the Viterbi (FEC) decoder. After decoding, the recovered clock and data pass to the de­framer (if EDMAC is enabled) where the overhead information is removed.

Chapter 3.
FUNCTION

Rev. 1.3 3–1

Function CDM-500 Closed Network Satellite Modem

Following this, the data passes to the Plesiochronous/Doppler buffer, which has a
programmable size, or may be bypassed. From here, the receive clock and data signals
are routed to the terrestrial interface, and are passed to the externally connected DTE
equipment.

3–2 Rev. 1.3

PHYSICAL DESCRIPTION

The CDM-500 is constructed as a 1U high rack-mounting chassis, which can be
free-standing, if desired. It is provided with rack-handles at the front to facilitate
its removal from, and placement into a rack. Figure 1 shows the front and rear
panels of the modem.

4.1 Front Panel

On the front panel of the unit is the Vacuum Fluorescent Display (VFD), 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 unit.

The Vacuum Fluorescent Display (VFD) is an active display showing 2 lines, each of 24
characters. It produces a pleasing 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 of viewing angle or contrast.

The keypad comprises 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 UP ARROW, DOWN ARROW,
RIGHT ARROW, LEFT ARROW, ENTER and CLEAR. The functions of these keys are
described in the ‘Front Panel Operation’ section.

There are 8 LED indicators. The functions of these indicators are shown in the Table 1
below:

Chapter 4.

4

Rev. 1.3 4–1

Physical Description CDM-500 Closed Network Satellite Modem

Table 4-1- Front Panel Led Indicators

LED Color Condition

Red A Unit Fault exists (Example: PSU fault)

Unit Status

Transmit

Traffic

Receive

Traffic

On line

Stored

Event

Remote

EDMAC

Mode

Test Mode

Orange No Unit Faults, but a Traffic Fault exists
Green No Unit Faults, or Traffic Faults

Green No Tx Traffic Faults
Off A Tx Traffic fault exists

OR the Tx Carrier is in OFF state

Green No Rx Traffic Faults (demod and Viterbi decoder are

locked, everything is OK)

Off An Rx Traffic fault exists (the demod may still be OK)
Green The Unit is On Line, and carrying traffic

Off The Unit is Off Line (standby) - forced by externally

connected 1:1 or 1:N redundancy system

Orange There is a Stored Event in the log, which can be viewed

from the front panel, or retrieved via the remote control
interface

Off There are no Stored Events
Orange The Unit is in Remote Mode - local monitoring is

possible, but no local control

Off The Unit is in Local Mode - remote monitoring is

possible, but no remote control

Orange Framing on, EDMAC on, and unit defined as Slave
Off Either no EDMAC, EDMAC Master, or Transparent

mode is selected
Orange A Test Mode is selected (Example: IF Loopback)
Off There is no Test Mode currently selected

Figure 4-1 Front and Back panels

4–2 Rev. 1.3

CDM-500 Closed Network Satellite Modem Physical Description

4.2 Rear Panel

All external cables are attached to connectors on the rear panel of the CDM-500. These
comprise the IEC line input connector, the Receive and Transmit IF connectors, the Data
connector, Alarms connector, Remote Control connector, and Auxiliary Serial connector.

The IEC line input connector contains the ON/OFF switch for the unit. It is also fitted
with two fuses - one each for line and neutral connections (or L1, L2, where appropriate).
These are contained within the body of the connector, behind a small plastic flap.

For 230 volt AC operation, use T0.5A, (slow-blow) 20mm fuses.
For 115 volt AC operation, use T1A fuses, (slow-blow) 20mm fuses.

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

The IF port connectors are both a 50 ohm BNC female type. 75 ohm cable connectors
(male) will have no problem mating with this 50 ohm type. The Data connector is a 25
pin ‘D’ type female (DB25-F). This connector conforms to the EIA 530 pinout, which
allows for connection of different electrical standards, including EIA-422, V.35, and
EIA-232. Please note that it is the responsibility of the user to provide the appropriate
cables to connect to this EIA 530 connector. A shielded 25 pin ‘D’ type provides a very
solid solution to EMC problems, unlike the sometimes used V.35 Winchester connector.
The pinout for the EIA 530 connector is provided in the next section.

Note that currently selected interface type is indicated by a small orange LED which is
located immediately above the connector. This provides aa easy visual indication to
anyone mating a connector at the rear of the unit.

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. In addition, 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. A pin is also
provided which can mute the transmit carrier. This requires that the pin be shorted to
ground, or a TTL ‘low’, or an EIA-232 ‘high’ signal be applied. The pinout details for
this connector are provided in the next section.

The Remote Control connector is a 9 pin 'D' type female (DB9-M). Access is provided to
remote control ports of the modem, both EIA-232 and EIA-485. The pinout details for
this connector are provided in the next section.

The Auxiliary Serial connector is an HE1402 3 pin header. A suitable mate for this
connector is AMP part number 281838-3, with three crimp pins, AMP part number
182734-2, also required. This is an additional EIA-232 serial port, which is only used
when the modem is part of a 1:1 pair, at the distant-end of a link, and when both units are
defined as EDMAC slaves. The pinout details for this connector are provided in the next
section.

Rev. 1.3 4–3

Physical Description CDM-500 Closed Network Satellite Modem

This page is intentionally blank.

4–4 Rev. 1.3

CONNECTOR PINOUTS

5.1 Connector Pinouts

Chapter 5.

5

5.1.1 Data Connector

Pin Generic Signal

description

1 Shield - Shield FG AA 101
2 Transmit Data A DTE to Modem SD A SD A BA 103
3 Receive Data A Modem to DTE RD A RD A BB 104
7 Signal Ground - SG SG AB 102
8 Receiver Ready A Modem to DTE RR A RLSD* CF 109
9 Receive Clock B Mod em to DTE RT B SCR B - 115
10 Receiver Ready B Modem to DTE RR B - - 109
11 Transmit Clock B DTE to Modem TT B SCTE B - 113
12 Internal Transmit Clock B Modem to DTE ST B SCT B - 114

14 Transmit Data B DTE to Modem SD B SD B - 103
15 Internal Transmit Clock A Modem to DTE ST A SCT A DB 114

16 Receive Data B Modem to DTE RD B RD B - 104
17 Receive Cl ock A Modem to DTE RT A SCR A DD 115
23 External Carrier Off

(RS232 ‘1' or TTL ‘low’ )

24 Transmit Clock A DTE to Modem TT A SCTE A DA 113

NOTES:

Receiver ready is an RS232-level control signal on a V.35 interface

•

-

25 Pin ‘D’ Type Female

Table 5-1 25 Pin ‘D’ Type Female

Direction RS422/ EIA

DTE to Modem - - - -

530

V.35 RS232 Circuit

No

Rev. 1.3 5–1

Connector Pinouts CDM-500 Closed Network Satellite Modem

• DO NOT connect signals to pins which are not shown - these pins are reserved for
use by the redundancy system

‘B’ signal lines are not used for RS232 applications

•

For X.21 operation, use the RS422 pins, but ignore Receive Clock if the Modem is

•

DTE, and ignore Transmit clocks if the Modem is DCE

5.2 Alarms Connector - 15 Pin ‘D’ Type Male

Table 5-2 Alarms Connector

Pin Description

1 Ground
5 Unit Fault Relay - Normally Open
12 Unit Fault Relay - Normally Closed
4 Unit Fault Relay - Common
8 Receive Traffic Relay - Normally Open
15 Receive Traffic Relay - Normally Closed
7 Receive Traffic Relay - Common
14 Transmit Traffic Relay - Normally Open
6 Transmit Traffic Relay - Normally Closed
13 Transmit Traffic Relay - Common
11 Receive I sample (for constellation display)
3 Receive Q sample (for constellation display)
2 Receive AGC voltage
9 External Carrier Off input
10 ---- No Connection ----

Note:
‘Normally Open’ refers to the NON-FAIL state

5–2 Rev. 1.3