WAVECOM EasySatSystem Software W61 v1.1 User...

WAVECOM EasySatSystem Software W61 v1.1

User Manual

by WAVECOM ELEKTRONIK AG

PUBLISHED BY

WAVECOM ELEKTRONIK AG

Hammerstrasse 8

CH-8180 Buelach

Switzerland

Phone +41-44-872 70 60

Fax +41-44-872 70 66

Email: [email protected]

Internet: http://www.wavecom.ch

© by WAVECOM ELEKTRONIK AG. All rights reserved.

Reproduction in whole or in part in any form is prohibited without written consent of the copyright owner.

The publication of information in this document does not imply freedom from patent or other protective rights of WA-VECOM ELEKTRONIK AG or others.

All brand names in this document are trademarks or registered trademarks of their owners.

Specifications are subject to change without further notice

Printed: Wednesday, March 26, 2008, 17:04:46

WAVECOM EasySatSystem Software W61 v1.1 User Manual Contents v

Contents

Welcome 1

Introduction ............................................................................................. 1 Professional Version ................................................................................... 1 Training ................................................................................................... 1 Source Code ............................................................................................. 1 Company Profile ........................................................................................ 1 Revisions ................................................................................................. 2 References ............................................................................................... 2

Software 2

Installation ............................................................................................... 2 Setup ...................................................................................................... 3 Operation ................................................................................................. 6 Error Handling .......................................................................................... 7 Source ..................................................................................................... 7

Hardware Recommendations 7

Overview ................................................................................................. 7 General Description of the components ......................................................... 7

Antenna ........................................................................................ 7 Downconverter ............................................................................... 8 PC with W61PC(s) ........................................................................... 8

Proven Components ................................................................................... 8 Antenna ........................................................................................ 8 Downconverter ............................................................................... 8 PC ................................................................................................ 8

Glossary of Terms 9

Index 29

WAVECOM EasySatSystem Software W61 v1.1 User Manual Welcome 1

Welcome

Congratulations on your purchase of a WAVECOM decoder. The product that you bought incorporates the latest technology in data decoding together with the latest software release available at the time of ship-ment.

Please, check our website http://www.wavecom.ch for software updates.

Always check the latest documentation on the installation CD or on our website.

We thank you for choosing a WAVECOM decoder and look forward to work with you in the future.

This chapter introduces WAVECOM ELEKTRONIK AG, the field of activity of the company, and how you may benefit from the expertise of WAVECOM ELEKTRONIK AG.

This document describes the 'EasySatSystem' software of WAVECOM ELEKTRONIK AG; this product is sometimes also called 'SAT-Coordination'.

Introduction

'EasySatSystem' controls the satellite-modes running on a system of up to 10 W61PC cards such to pre-vent that more than one W61PC card monitors the same satellite communications session, identified by a specific satellite-mode (INMARSAT-B, INMARSAT-M, and INMARSAT-mini-M), a service (data, fax, ISDN, etc.), and mobile earth station identification number (termed MES Id in the following). The monitoring system configuration is specified in a text file using a very simple syntax. For logging purposes, statistical data concerning the monitored sessions can be collected.

'EasySatSystem' has 3 kinds of user interfaces:

the operational status display of the coordinated cards, i.e., the ‘EasySatSystem’ graphical user in-terface (GUI);

the configuration interface, i.e., the text file EasySATSystem.ini, stored in some predefined direc-tory;

the MS-DOS command line with parameters.

Professional Version

This documentation is only available in the professional version of the WAVECOM decoder software.

Professional versions are only available to government bodies.

WAVECOM maintains a mailing list of our professional customers. For registration details, see Appendix at the end of this manual.

Training

Please, note that when required WAVECOM is able to provide training on the WAVECOM XML interface. Training can be ordered to take place at the customer location or at our offices in Switzerland.

Source Code

Source code is available for professional users. To obtain the Source Code please contact WAVECOM, at www.wavecom.ch.

Company Profile

2 Software WAVECOM EasySatSystem Software W61 v1.1 User Manual

WAVECOM ELEKTRONIK GmbH was founded in 1985 in Hohentengen, Germany, close to the Swiss border. In 1991 the company moved to Switzerland and established itself as WAVECOM ELEKTRONIK AG. Now lo-cated in Buelach it is within close vicinity of Zuerich airport.

The company has focused on decoding and analysis systems for wireless data transmissions. The wide product range spans from professional, high performance systems to devices for private and amateur ra-dio use.

The very high quality standards combined with high system performance are appreciated by all customers worldwide. A global network of authorized sales partners ensures that local assistance and basic level sup-port can be provided in most places. More than 95% of all units sold are exported. The majority of the customers are government agencies, defense organizations and the telecommunication industry.

About 40% of the turnover is invested in research and development. The employees at WAVECOM ELEK-TRONIK AG are mainly engineers with experience in DSP technology, computer and RF hardware devel-opment, software engineering and radio data transmission. Access to external know-how and human re-sources enlarges the capabilities for realizing projects. Manufacturing is outsourced to specialized compa-nies within Switzerland which can handle today's needs for processing surface mount components and fine-pitch structures.

WAVECOM ELEKTRONIK AG does not have any juridical or financial links or connections to other compa-nies or official bodies and is completely owned by its general manager, Mr. Christian Kesselring.

Revisions

Version Date Author Changes

0.1 16-01-2006 Hgr Initial draft

0.2 26-01-2006 Hgr Corrections after comments from RH

Install, Setup, Error handling, Source chapters added;

.Ini file description adapted to new format;

1.0 13-02-2006 Hgr Corrections after review MO, RH

1.001 29-03-2006 Hgr Addition of Command Line parameter /A:<n2>

1.002 25-10-2006 Hgr Reviewed version, Glossary added

1.003 03-11-2006 Hgr optional argument /L changed

1.1.000 10-03-2008 Hgr New directories for config and data, under :

documents and settings\All users\documents\ wavecom \easysat\config and …\data

References

[1] WAVECOM ELEKTRONIK AG, EasySatSystem Specification, V 0.2

Software

Installation

During the installation of the product ‘EasySatSystem’ by means of the provided setup program, the direc-tory into which the software shall be installed is specified. Hereafter, this directory is denoted as <easysatsystem_dir>. The following files can be found in <easysatsystem_dir>:

EasySatSystem.exe (the main and only executable)

XMLRCICPP.dll (a required DLL)

EasySATSystemUserManual.pdf (this document)

WAVECOM EasySatSystem Software W61 v1.1 User Manual Software 3

FileHandler.exe (a program solely needed during the installation of ‘EasySatSystem’)

WAVECOM_Decoder.chm, the Helpfile

Administrator privileges are required to modify the contents of the directory <easysatsystem_dir>

The Config file is stored in the directory (referred to as <easysatsystem_config_dir>):

C:\Documents and Settings\All Users\Documents\WAVECOM \EasySat System\Config.

This directory contains the files:

EasySatSystem.ini

Template-EasySatSystem.ini.

By default, after start of EasySATSystem.exe, the program looks in this <easysatsystem_config_dir> di-rectory for the required configuration file EasySATSystem.ini. However, a different directory can be speci-fied by setting the environment variable EASYSATSYSTEM_CONFIG_DIR accordingly.

The collected data will be stored in the directory (referred to as <easysatsystem_data_dir>):

C:\Documents and Settings\All Users\Documents\WAVECOM \EasySatSystem\Data.

By default, the <easysatsystem_data_dir> directory will be used to store statistical data files (if logging has been enabled; see below). Again, a different directory can be specified by setting the environment variable EASYSATSYSTEM_DATA_DIR accordingly.

User privileges are sufficient to modify (i.e., also delete) the subdirectories \Config and \Data as well as their respective contents.

In order to have ‘EasySatSystem’ working properly, the 'XML Remote Control Interface' port has to be opened on each personal computer (PC) hosting W61PC cards to be coordinated. This is done as follows:

1. Open 'Control Panel';

2. Open 'Windows Firewall';

3. If the 'On' button is set, then clear the 'Don't allow exceptions' checkbox;

4. Select the 'Exceptions' tab;

5. Click on 'Add Port…' and give a name and set the port number to the default value of 33234, or to the value you have specified in the tab ‘Networking Information’ of the W61PC WavecomServer-Control GUI;

6. For test purposes, it might also be necessary to open the port for the GUI of W61PC (default value of 33233).

Furthermore, on each PC hosting W61PC cards to be coordinated, the respective WavecomService must be running and allow remote connections. In order to allow remote connections to a WavecomService, check the box ‘Allow Remote Connections’ in the tab ‘Networking Information’ of the respective W61PC Wave-comServerControl GUI.

Setup

'EasySatSystem' can run on any PC under the Microsoft Windows XP or Vista operating system. If cards on more than one PC must be coordinated, then the PCs must be connected via a network.

'EasySatSystem' must be told somehow which PCs with which W61PC cards it must coordinate. This is done with the configuration file EasySATSystem.ini, which, by default, needs to be located in the directory <easysatsystem_config_dir>. An alternative location can be specified by means of the environment vari-able EASYSATSYSTEM_CONFIG_DIR.

In the EasySATSystem.ini file, one can also specify the sessions to exclusively be watched by listing the respective MES Ids; if no MES Id is specified, then all sessions will be watched.

It is also possible to specify the duration (in seconds) of the automatic level setting (ALS) performed at mode start-up. Only the first valid value specified will be used, if several are given in EasySATSystem.ini.

If desired, ‘EasySatSystem’ collects statistical data concerning the monitored sessions. In such a case, when exiting ‘EasySatSystem’, a respective text file is stored in the directory <easysatsystem_data_dir> or in the directory specified by the environment variable EASYSATSYSTEM_DATA_DIR if it is set. The name of such a file is ‘Stat<dateAndTime>.txt’, where <dateAndTime> denotes the date and time (includ-ing seconds) of the log-file creation, which occurs at the end of a monitoring session with ‘EasySatSys-tem’. Be aware that such a file may become quite large. To enable statistical logging, a sampling interval (in seconds) greater than 0 has to be specified in EasySATSystem.ini. Only the first valid value specified will be used, if several are given in EasySATSystem.ini.

The name of the configuration file must be 'EasySATSystem.ini' (case-insensitive).


Below, the syntax of the configuration file is specified, for which the following rules apply:

Whitespace (blanks, tabs) can be expanded to any length;

EOL means end-of-line;

* means repetition 0 or more times;

Single superscript (e.g., xyz10) means repetition exactly the given number of times;

Range superscript (e.g., xyz1-9) means repetition with minimum and maximum bounds;

Bold words must appear exactly as shown;

| means alternative;

Terms in <…> are expanded;

The starting point for the syntax is <config>. <config> ::= <section>*

<section> ::= <cardSection> | <mesWatchSection>

| <alsPeriodSection> | <logPeriodSection>

<cardSection> ::= <cardSectLine>EOL

<addrLine>EOL<snLine>EOL<modeLine>EOL

<cardSectLine> ::= [card_<n>] <n> running number starting at 1

<addrLine> ::= address = <nameOrIPAddress>; <nameOrIPAddress> ::= char

1-30

<snLine> ::= serialno = <serialNo>; <serialNo> ::= numchar

10

<modeLine> ::= <mode>;

<mode> ::= sat-b | sat-m | sat-mini-m

<mesWatchSection> ::= <watchSectLine>EOL<watchLine>EOL

<watchSectLine> ::= [watch]

<watchLine> ::= mesid = <mesIdNo> ; <mesIdNo> ::= numchar

1-8

<alsPeriodSection> ::= <alsPeriodSectLine>EOL<periodLine>EOL

<alsPeriodSectLine> ::= [als]

<logPeriodSection> ::= <logPeriodSectLine>EOL<periodLine>EOL

<logPeriodSectLine> ::= [log]

<periodLine> ::= period = <seconds> ; <seconds> ::= numchar

Note:

The string <nameOrIPAddress> can be the PC name, or the dotted IP address of the PC. The local PC of 'EasySatSystem' can also be denoted by 127.0.0.1.

A maximum of 10 card-sections can be specified. Each card can run on its own PC, so there can be a maximum of 10 PCs. One PC can have a maximum of 8 cards.

The number of MES Id watch-sections is not limited.

Following are two examples of valid configuration files. Example 1 shows the configuration file for a sys-tem with 4 cards configured for INMARSAT-B, 1 for INMARSAT-M and 5 for INMARSAT-mini-M, residing on 2 different PCs (Niklaus2 and Test-w61pc). All MES Ids shall be considered, no ALS shall be performed, and no statistical data shall be collected. In Example 2, the system to be monitored consists of 3 different PCs and 4 cards: the local one (127.0.0.1) with one card and two remote hosts, 123.45.67.89 with one card and ComputerA with two cards. On all cards INMARSAT-B transmissions with specific MES Ids shall be monitored. Furthermore, ALS shall be performed for a period of 5 minutes (300 seconds), and statistical data shall be collected every 30 seconds.

WAVECOM EasySatSystem Software W61 v1.1 User Manual Software 5

Example 1: [card_1]

address = Niklaus2;

serialno= 0508002720;

mode = sat-b;

[card_2]

address = Niklaus2;

serialno= 0508001120;

mode = sat-b;

[card_3]

address = Test-w61pc;

serialno= 0508007220;

mode = sat-b;

[card_4]


serialno= 0508004620;

mode = sat-b;

[card_5]


serialno= 0508005620;

mode = sat-m;

[card_6]


serialno= 0508008320;

mode = sat-mini-m;

[card_7]


serialno= 0508002120;

mode = sat-mini-m;

[card_8]


serialno= 0508010020;

mode = sat-mini-m;

[card_9]


serialno= 0508003620;

mode = sat-mini-m;

[card_10]


serialno= 0508003920;

mode = sat-mini-m;

Example 2: [card_1]

address = 127.0.0.1;

serialno= 0508002720;

mode = sat-b;

[card_2]

address = ComputerA;

serialno= 0508001120;

mode = sat-b;

[card_3]

address = 123.45.67.89;

serialno= 0508007220;

mode = sat-b;

[card_4]

address = ComputerA;

serialno= 0508004620;

mode = sat-b;

[watch]

mesid = 12345;

[watch]

mesid = 54321;

[watch]

mesid = 67890;

[watch]

mesid = 98765;

[als]

period = 300;

[log]

period = 30;

The rules must be followed strictly; if there is an error in the EasySATSystem.ini file, the corresponding card will not be included in the coordination process.


Operation

'EasySatSystem' must be started by the user. The command to start ‘EasySatSystem’ has the following format:

<easysatsystem_dir>/EasySatSystem [/L:<n1>] [/A:<n2>]

The optional argument /L indicates that statistics data should be collected. The number <n1> must be in the range 4..120. This number specifies the sampling interval for the statistics data in seconds; (approxi-mately) every n1 seconds a snapshot of the busy status of each card is taken and written at program ter-mination to the statistics file Stat<dateAndTime>.txt in <easysatsystem_data_dir> or in the directory specified by the environment variable EASYSATSYSTEM_DATA_DIR if it is set. If this argument is not pre-sent, or n1 is not in the range 4..120, no statistics data will be collected. A sampling interval specified in the configuration file EasySATSystem.ini has precedence over the value passed as argument on the com-mand line. Absence of both parameters indicates that no statistical data has to be collected.

The optional argument /A specifies the duration (in seconds) of the ALS that will be performed on each card. An ALS period specified in the configuration file EasySATSystem.ini has precedence over the value passed as argument on the command line. Absence of both parameters indicates that no ALS has to be done.

After starting ‘EasySatSystem’, a new window appears on the display, showing one line of status informa-tion for each correctly configured W61PC card, as well as the specified ALS period, sampling interval, and MES Id watch-list. The maximum number of cards is fixed to maxN=10, since the window has space for exactly this number. If less than maxN cards are configured, the remaining lines contain empty fields.

For each configured card the following information is shown:

Column heading meaning

Number This is the global number of the card within the scope of the coordinated cards;

range: 1..maxN.

SAT Mode The SAT mode configured on this card.

Computer Name or IP Address Address of the computer of this card; can be the (dotted) IP address or the computer name; maximum length 30 characters.

Serial # Serial number of this card.

Op Status Operational status of the card, this can be:

'Not Connected': the PC of this card is not under control of ‘EasySatSystem’;

'Host Connected' (transient): the PC has answered to ‘EasySatSystem’ and an-nounced all its cards;

'Card Ready' (transient): the card has answered;

'Mode Running': the mode was set on the card;

'Busy Session': the card is monitoring a SAT session.

MESId If Op Status is ' Busy Session', this is the forward MES Id of the terminal being

in the monitoring session, otherwise this field is empty;

Service If Op Status is ' Busy Session', this is the service being monitored, otherwise

this field is empty

The term ‘transient’ means that this state may last only a very short time, and is therefore possibly not visible for the user.

If a configured card is not shown at all, then there must be an error in the respective card’s specification in the EasySATSystem.ini file.

There is only one button available, named 'Exit'. Pressing this button will terminate the program, as will pressing the 'Close' button in the window frame.

Note:

At start-up, 'EasySatSystem' does not automatically synchronise with the operational status of the cards, meaning that, if a card is already in a session, this is not shown. Only at the next status change of the card, the ‘Op Status’ field will display the correct status.

It can take some time until the program has properly terminated after pressing 'Exit' or 'Close'.

The system does not check if more than one instance of 'EasySatSystem' coordinates the same card(s). So make sure to start this program with the same cards configured only once.

It is recommended to manually control from time to time the signal level settings at the different cards under the control of ‘EasySatSystem’, also when ALS is enabled.

WAVECOM EasySatSystem Software W61 v1.1 User Manual Hardware Recommendations 7

Error Handling

'EasySatSystem' tries to connect configured, but not connected cards approximately every 30 seconds. All cards not connected are shown in the ‘Op Status’ field accordingly.

Source

To obtain a Source Code License please contact WAVECOM ELEKTRONIK AG, at http://www.wavecom.ch.

Hardware Recommendations

This document describes how the WAVECOM W61PC card with the optional W61SAT SW can be used to implement a simple INMARSAT L-Band Monitoring system. A brief overview of the INMARSAT System is given in the help file of the W61PC.

Overview

The W61SAT SW allows the monitoring of the L-Band downlink (in the 1550 MHz range, also called for-ward path) of the INMARSAT System. This link contains the information from the Land Earth Station to the Mobile Earth Stations, MES.

The Monitoring System consists of 3 main components:

Antenna, including a low noise amplifier, LNA;

Downconverter, L-Band to 70 MHz IF;

PC(s) with W61 card(s) and the optional W61SAT SW; the PC requirements: > 1 GHz, 512 MB RAM, 60 GB HD, CD;

These components are connected with coax cable. If more than 1 W61 is to be fed with the same signal, a splitter should be used to correctly match the impedance of the W61 70 MHz input (input IF70#4, 50 Ohm).

General Description of the components

Antenna

The antenna system must have a figure of merit G/T > 0 dB/K, this is easy possible with a parabolic dish of at least 2 m diameter and a low noise amplifier with a noise figure of 0.8 dB. The polarization of the L-

Downconver-ter

PCs with W61 cards and W61SAT SW

Antenna

indoor outdoor

coax signal ca-ble

L-Band

W61

W61

W61

W61

W61

W61

8 Hardware Recommendations WAVECOM EasySatSystem Software W61 v1.1 User Manual

Band signal is RHCP, so if a parabolic reflector is used, the feed must pick up the LHCP component (mirror effect).

There is no tracking of the satellite necessary, the antenna can be of a fixed type, which is installed and aligned to the satellite only once.

Downconverter

This is a commercial product, converting L-Band to 70 MHz IF with a bandwidth of +/- 20 MHz.

PC with W61PC(s)

These are commercially available computers, with a Pentium processor running under the Microsoft XP Operating System, with at least 1 PCI slot for the W61 card. CPU clock rate should be > 1 GHz, RAM >= 512 MB, and HD of 60 GB, the W61 SW takes about 40 MB, but the disk is used by the collected data from monitoring.

Proven Components

A system with the following components has been tested at WAVECOM ELEKTRONIK AG, and can be used.

Antenna

Loopyagi (low cost solution)

A L-Band loopyagi antenna, type 2045LY, from Directive Systems [http://www.directivesystems.com/] to-gether with a low-noise amplifier, MKU 152 A, from Kuhne electronic [http://www.kuhne-electronic.de/] allows monitoring the local spot beams with reasonable success. The L-Band signal is connected to the re-ceiver directly.

Dish antenna

WAVECOM ELEKTRONIK AG uses a 3.7 m epoxy-glass resin dish reflector, with an integrated Feed-LNA from Köditz Nachrichtentechnik [http://www.koeditz-nachrichtentechnik.de/]. The L-Band signal goes di-rectly to the converter.

WAVECOM also tested a dish of only 0.7 m diameter with a LNA/feed from SSB electronics (http://www.ssb.de/ but not available any longer) with very useful results.

The INMARSAT mini M system is based on spot beams for coverage. This allows to build terminals with a small antenna, but for monitoring, it is impossible to receive all spot beams at a given geographic location. In order to catch also the signals from a neighboring spot beam, the antenna must have more gain, which means a bigger dish than necessary for the local spot beam.

WAVECOM recommends a dish of at least 2.4 m diameter.

Downconverter

At WAVECOM a type MP-9201 Satellite Downconverter from Micro Phase Communications, Inc is used (http://www.microphaseinc.com).

PC

A Dell computer of the type Dimension 8200 is in use at WAVECOM ELEKTRONIK AG.

http://www.directivesystems.com/

http://www.kuhne-electronic.de/

http://www.koeditz-nachrichtentechnik.de/

http://www.ssb.de/

http://www.microphaseinc.com/

WAVECOM EasySatSystem Software W61 v1.1 User Manual Glossary of Terms 9

Glossary of Terms

ADC

Analog-to-Digital Conversion.

Process of converting analog signals to a digital representation. DAC represents the reverse translation.

AFC

Automatic Frequency Control.

A circuit which automatically controls the frequency of a signal.

AGC

Automatic Gain Control.

A circuit which automatically controls the gain of an amplifier so that the output signal level is virtually constant for varying input signal levels.

ALC

Automatic Level Control.

A circuit which automatically controls the gain of a receiver so that the output signal level is virtually con-stant.

ALS

Automatic Level Setting.

The process of ALC.

AM

Amplitude Modulation.

The baseband signal is caused to vary the amplitude or height of the carrier wave to create the desired in-formation content.

Amplifier

A device used to boost the strength of an electronic signal.

Antenna

A device for transmitting and receiving radio waves. Depending on their use and operating frequency, an-tennas can take the form of a single piece of wire, a dipole a grid such as a Yagi array, a horn, a helix, a sophisticated parabolic-shaped dish, or a phase array of active electronic elements of virtually any flat or convoluted surface.

AOS

Acquisition of Signal.

The time or location where a satellite is in line of sight.

Aperture

The cross sectional area of the antenna exposed to the satellite signal.

10 Glossary of Terms WAVECOM EasySatSystem Software W61 v1.1 User Manual

Apogee

The point in an satellite orbit where the satellite is the highest (farthest distance) from the surface of the earth. Usually measured from the center of the earth.

APRS

Automatic Position Reporting System.

A system developed by Bob Bruninga, WB4APR, for tracking and digital communications with mobile GPS equipped stations with two-way radio.

Asymmetric transmission

Where the information or data transmission speeds for the forward and return channels differ (e.g. high speed for the forward channel and low for return).

Asynchronous transmission

A method of data transmission which allows characters to be sent at irregular intervals by preceding each character with a start bit, and following it with a stop bit.

Attenuation

The loss in power of electromagnetic signals between transmission and reception points.

Availability

The ratio, expressed as a percentage, of the total time a functional unit or service is capable of being used or is available to be used during a given interval to the length of the interval; e.g., if the unit is not capa-ble of being used for 20 minutes in a week, the availability is 99.8 percent (10080 - 20 minutes/10080 minutes * 100).

AZ/EL Mount Antenna mount that requires two separate adjustments to move from one satellite to another.

Azimuth

Angle between true north and a particular satellite. Can be measured with a compass.

Backoff The process of reducing the input and output power levels of a traveling wave tube to obtain more linear operation.

Band Pass Filter

An active or passive circuit which allows signals within the desired frequency band to pass through but im-pedes signals outside this pass band from getting through.

Bandwidth

A measure of spectrum (frequency) use or capacity. For instance, a voice transmission by telephone re-quires a bandwidth of about 3000 cycles per second (3KHz). A TV channel occupies a bandwidth of 6 mil-lion cycles per second (6 MHz) in terrestrial systems. In satellite based systems a larger bandwidth of 17.5 to 72 MHz is used to spread or "dither" the television signal in order to prevent interference.

Baseband

The basic direct output signal in an intermediate frequency based obtained directly from a television cam-era, satellite television receiver, or video tape recorder. Baseband signals can be viewed only on studio


monitors. To display the baseband signal on a conventional television set a "modulator" is required to con-vert the baseband signal to one of the VHF or UHF television channels which the television set can be tuned to receive.

Baud

The rate of data transmission based on the number of signal elements or symbols transmitted per second. Today most digital signals are characterized in bits per second.

Beacon

Low-power carrier transmitted by a satellite which supplies the controlling engineers on the ground with a means of monitoring telemetry data, tracking the satellite, or conducting propagation experiments. This tracking beacon is usually a horn or omni antenna.

Beam width

The angle or conical shape of the beam the antenna projects. Large antennas have narrower beam widths and can pinpoint satellites in space or dense traffic areas on the earth more precisely. Tighter beam widths thus deliver higher levels of power and thus greater communications performance.

Bent Pipe Transponder

A "bent pipe" transponder is the term for a transponder that amplifies the received signal and retransmits it to earth without demodulation. It may be a linear transponder, like FO-29, INMARSAT A,B, C, M, that will handle multiple signals as long as they are near the same signal level at the satellite or a limiting transponder that is captured by the strongest signal. Limiting transponders have higher power efficiency than linear transponders.

Bird

Slang for a communications satellite located in geosynchronous orbit.

Bit A single digital unit of information.

Bit Error Rate

The fraction of a sequence of message bits that are in error. A bit error rate of 10e-6 means that there is an average of one error per million bits.

Bit Rate

The speed of a digital transmission, measured in bits per second.

Byte Sequence or group of eight bits. 1 byte = 8 bits; 1 Kbyte = 1,024 bytes; 1Mbyte = 1,024 Kbytes; 1Gbyte = 1,024 Mbytes.

Block Down Converter

A device used to convert signals in the frequency range above 1 GHz down to UHF or lower frequencies (1 GHz and lower).

BPSK

Binary Phase Shift Keying.

A digital modulation scheme used in transmission communications.


Broad beam

A single large circular beam that covers a large geographic area, sometimes also called Global beam.

Broadcast The sending of one transmission to multiple users in a defined group (compare to unicast).

Byte

A sequence of eight adjacent binary digits usually treated as a unit.

C/N

Carrier to Noise Ratio.

The ratio of the received carrier power and the noise power in a given bandwidth, expressed in dB. This figure is directly related to G/T and S/N; and in a video signal the higher the C/N, the better the received picture.

C/T

Carrier-to-noise-temperature ratio.

Call 1. Any demand to set up a connection.

2. A unit of traffic measurement.

Carrier

The basic radio, television, or telephony center of frequency transmit signal. The carrier in an analog sig-nal. is modulated by manipulating its amplitude (making it louder or softer) or its frequency (shifting it up or down) in relation to the incoming signal. Satellite carriers operating in the analog mode are usually fre-quency modulated.

Carrier Frequency

The main frequency on which a voice, data, or video signal is sent. Microwave and satellite communica-tions transmitters operate above 1 GHz (a GHz is one billion cycles per second).

C-Band

This is the band between 4 and 8 GHz.

CDMA

Code division multiple access. Refers to a multiple-access scheme where stations use spread-spectrum modulations and orthogonal codes to avoid interfering with one another.

Channel A frequency band in which a specific broadcast signal is transmitted. Channel frequencies are specified in the United States by the Federal Communications Commission. Analog Television signals require a 6 MHz frequency band to carry all the necessary picture detail.

Circuit mode

A circuit switched operational mode for transferring (transporting and switching) user information through a network. Contrast with packet switching mode.


Clarke Belt The name given in honor of Arthur C. Clarke to the orbit 22,237 miles directly above the equator where satellites can maintain a stationary position in relation to the earth. Also called geo-stationary orbit.

This orbit was first postulated by the science fiction writer Arthur C. Clarke in Wireless World magazine in 1945. Satellites placed in these orbits, although traveling around the earth at thousands of miles an hour, appear to be stationary when viewed from a point on the earth, since the earth is rotating upon its axis at the same angular rate that the satellite is traveling around the earth.

Cliff effect Sudden breakdown or loss of digital signal reception when it contains more errors than the error correc-tion system can cope with. Up to this point there is no degradation in reception quality; a significant ad-vantage over analog where there is a gradual deterioration.

Codec

1. Coder/decoder system for digital television transmission.

2. The algorithm (HW or SW) for compressing digital voice.

Co-Location

Ability of multiple satellites to share the same approximate geostationary orbital assignment frequently due to the fact that different frequency bands are used.

Compression

A technique to reduce the amount of data to be transmitted that reduces the amount of bandwidth needed to transmit data, video or audio, thus increasing the capacity of a satellite transponder.

Data

Representation of facts, concepts, or instructions in a formalized manner suitable for communication, in-terpretation, or processing by humans or by automatic means.

dB

Decibel.

An analog unit of measure of signal strength, volume, or signal loss due to resistance as expressed in lo-garithmic form.

dBi The dB power relative to an isotropic source.

DBS

Direct broadcast satellite (for television). Refers to service that uses satellites to broadcast multiple chan-nels of television programming directly to home mounted small-dish antennas.

dBW

The ratio of the power to one Watt expressed in decibels.

Delay

The time it takes for a signal to go from the sending station through the satellite to the receiving station. This transmission delay for a single hop satellite connection is very close on one-quarter of a second.


Demodulation

The process for retrieving an information signal that has been modulated onto a carrier.

Demodulator

A unit which extracts or "demodulates" the "wanted "signals from the received carrier.

DES

Data Encryption Standard.

A cryptographic algorithm for the protection of unclassified computer data, issued as Federal Information Processing Standard Publication 46-1.

Deviation

The modulation level of an FM signal determined by the amount of frequency shift from the frequency of the main carrier.

Digital Conversion of information into bits of data for transmission through wire, fiber optic cable, satellite, or over air techniques. Method allows simultaneous transmission of voice, data or video.

Digital data

Data represented by discrete values or conditions (i.e., "0" or "1"), as opposed to analog data.

Digital voice

Analog voice signals that have been converted into digital signals.

Digitize

To convert analog signals into digital ones.

Dish

A parabolic antenna which collects and focuses satellite signals. C-Band antennas range in size from five to eight feet in diameter, and K-Band antennas range from 18 inches to five feet.

Downlink

The satellite to earth half of a 2 way telecommunications satellite link. Often used to describe the receive dish end of the link.

DSP

1. Digital Speech Processing.

2. Digital Signal Processing.

Duplex Transmission

Capability for simultaneous data transmission between a sending station and a receiving station.

DVB

Digital Video Broadcasting.

The European-backed project to harmonize adoption of digital video.


E1

Wide-area digital transmission facility used predominantly in Europe that carries data at a rate of 2.048 Mbit/s.

E3

Wide-area digital transmission facility used predominantly in Europe that carries data at a rate of 34.368 Mbit/s.

Earth Station

The term used to describe the combination or antenna, low-noise amplifier (LNA), down-converter, and receiver electronics. used to receive a signal transmitted by a satellite. Earth Station antennas vary in size from the.2 foot to 12 foot (65 centimeters to 3.7 meters) diameter size used for TV reception to as large as 100 feet (30 meters) in diameter sometimes used for international communications. The typical anten-na used for INTELSAT communication is today 13 to 18 meters or 40 to 60 feet.

Echo Canceller

An electronic circuit which attenuates or eliminates the echo effect on satellite telephony links. Echo can-cellers are largely replacing obsolete echo suppressors.

Edge of Coverage

Limit of a satellite's defined service area. In many cases, the EOC is defined as being 3 dB down from the signal level at beam center. However, reception may still be possible beyond the -3dB point.

EIRP

Effective Isotropic Radiated Power.

This term describes the strength of the signal leaving the satellite antenna or the transmitting earth sta-tion antenna, and is used in determining the C/N and S/N. The transmit power value in units of dBW is expressed by the product of the transponder output power and the gain of the satellite transmit antenna.

Elevation

Angle between the earth's surface and a particular satellite at a given reception point (0° for horizontal and 90° for vertical).

Encrypt To convert plain text into an unintelligible form by means of a cryptosystem.

EOL

End of Life of a satellite.

Equatorial Orbit An orbit with a plane parallel to the earth's equator.

F/D

Ratio of antenna focal length to antenna diameter. A higher ratio means a shallower dish.

FDMA

Frequency Division Multiple Access.

Refers to the use of multiple carriers within the same transponder where each uplink has been assigned frequency slot and bandwidth. This is usually employed in conjunction with Frequency Modulation.


FEC

Forward Error Correction.

A technique for improving the robustness of data transmission. Excess bits are included in the outgoing data stream so that error-correction algorithms can be applied upon reception. For the satellite standard the Viterbi code combined with the Reed Solomon code is used. Commercial use of transponders makes 3/4 and 5/6, which means that three out of four or five out of six bits contain useable information.

Feed

This term has at least two key meanings within the field of satellite communications. It is used to describe the transmission of video programming from a distribution center. It is also used to describe the feed sys-tem of an antenna. The feed system may consist of a sub reflector plus a feed horn or a feed horn only

Feed horn

The part of the satellite system that collects and focuses satellite signals reflected by the dish.

FM

Frequency Modulation.

Focal Length

Distance from the center feed to the center of the dish.

Focal Point The area toward which the primary reflector (dish) reflects received signal energy. This is where the feed system is typically located.

Footprint A map of the signal strength showing the EIRP contours of equal signal strengths as they cover the earth's surface. Different satellite transponders on the same satellite will often have different footprints of the signal strength. The accuracy of EIRP footprints or contour data can improve with the operational age of the satellite. The actual EIRP levels of the satellite, however, tends to decrease slowly as the spacecraft ages.

Forward path

The transmission path issued from the service provider and reaching the end user.

FPGA

Field-Programmable Gate Array.

This is an array of logic elements that are interconnected via an array of busses

Frequency

The number of times that an alternating current goes through its complete cycle in one second of time. One cycle per second is also referred to as one hertz; 1000 cycles per second, one kilohertz; 1,000,000 cycles per second, one megahertz: and 1,000,000,000 cycles per second, one gigahertz.

Frequency Coordination

A process to eliminate frequency interference between different satellite systems or between terrestrial microwave systems and satellites. In the U.S. this activity relies upon a computerized service utilizing an extensive database to analyze potential microwave interference problems that arise between organizations using the same microwave band. As the same C-band frequency spectrum is used by telephone networks


and CATV companies when they are contemplating the installation of an earth station, they will often ob-tain a frequency coordination study to determine if any problems will exist.

FTP

File Transfer Protocol.

The Internet protocol (and program) used to transfer files between hosts.

Full-duplex operation

A mode of operation in which simultaneous communication in both directions may occur between two ter-minals. In contrast to half duplex or simplex operation in which communications occur in only one direc-tion at a time.

G/T

A figure of merit of an antenna and low noise amplifier combination expressed in dB. "G" is the net gain of the system and "T" is the noise temperature of the system. The higher the number, the better the system.

Gain

A measure of amplification expressed in dB.

GAN

Global Area Network (INMARSAT M-4).

Gateway

In a communication network, one of the network nodes equipped for interfacing with a network using dif-ferent protocols. Note: A gateway may contain devices such as protocol translators, impedance matching devices, rate converters, fault isolation, or signal translators as necessary to provide system interopera-bility.

Geostationary

Refers to a geosynchronous satellite angle with zero inclination, so the satellite appears to hover over one spot on the earth's equator.

Geosynchronous Orbit (GSO) Satellite in geosynchronous orbit travel around the Earth in an area approximately 22,300 miles from the surface at the same rate that the Earth turns, therefore completing one revolution every 24 hours.

GHz

One billion cycles per second. Signals operating above 3 Gigahertz are known as microwaves, above 30 GHz they are known as millimeter waves. As one moves above the millimeter waves, signals begin to take on the characteristics of light-waves.

Global Beam

An antenna down-link pattern, which effectively covers one-third of the globe. Global beams are aimed at the center of the Atlantic, Pacific and Indian Oceans by the respective Intelsat satellites, enabling all na-tions on each side of the ocean to receive the signal. Because they transmit to such a wide area, global beam transponders have significantly lower EIRP outputs at the surface of the Earth as compared to a spotbeam. Therefore, earth stations receiving global beam signals need antennas much larger in size (typ-ically 10 meters and above (i.e., 30 feet and up).


GMDSS

Global Maritime Distress and Safety System.

GPS

Global Positioning System.

Half-duplex operation

That mode of operation in which communication between two terminals occurs in either direction but in only one direction at a time. Contrast with duplex or simplex operation. Note: Half-duplex operation may occur on half-duplex circuits or on duplex circuits, but it may not occur on simplex circuits.

HGS

Hughes Global Services, Inc.

High Power Amplifier (HPA)

Equipment used to amplify signals.

Hub

The master station through which all communications to, from and between micro terminals must flow. In the future satellites with on-board processing will allow hubs to be eliminated as MESH networks are able to connect all points in a network together.

Hybrid satellite

A satellite which carries two or more different communications payloads (i.e., C-band and Ku-band).

Hz

Hertz.

The name given to the basic measure of radio frequency characteristics. An electromagnetic wave com-pletes a full oscillation from its positive to its negative pole and back again in what is known as a cycle. A single Hertz is thus equal to one cycle per second.

IBS

INTELSAT Business Services.

Inclination

The angle between the orbital plane of a satellite and the equatorial plane of the earth.

INMARSAT

The International Maritime Satellite Organization operates a network of satellites for international trans-missions for all types of international mobile services including maritime, aeronautical, and land mobile.

Established in 1979 to serve the maritime industry by developing satellite communications for ship man-agement and distress and safety applications, INMARSAT currently operates a global satellite system which is used by independent service providers to offer an unparalleled range of voice and multimedia communications for customers on the move or in remote locations.

INMARSAT-A: INMARSAT original phone, fax and data system

INMARSAT-B: Digital successor to INMARSAT-A

INMARSAT-B HSD: 64 Kbit/s high speed data option

INMARSAT-C: Store-and-forward data through briefcase terminals


INMARSAT-D, D+: Global messaging and data broadcasts to pager-sized terminals

INMARSAT-E: Global alerting services via INMARSAT

INMARSAT-mini-M: INMARSAT smallest satellite phones for voice, fax and data

INMARSAT Aero-I: INMARSAT latest aeronautical satcoms service

Interference

Energy which tends to interfere with the reception of the desired signals, such as fading from airline flights, RF interference from adjacent channels, or ghosting from reflecting objects such as mountains and buildings.

Intermodulation

No amplifier is perfectly linear, so multiple signals will be combined with each signal unintentionally mod-ulating others in the pass band to some extent. The amount of distortion increases with the signal power levels. The third order intercept is most important for linear transponders and the power level of the third-order distortion products increases at three times the rate at which the original signal levels increase.

Internetworking

The process of interconnecting a number of individual networks to provide a path from a terminal or a host on one network to a terminal or a host on another network. The networks involved may be of the same type, or they may be of different types. However, each network is distinct, with its own addresses, internal protocols, access methods, and administration.

IRIDIUM

A LEO based satellite voice, messaging and paging system.

ISDN

Integrated Services Digital Network.

A CCITT standard for integrated transmission of voice, video and data. Bandwidths include: Basic Rate In-terface - BR (144 Kbps - 2 B & 1 D channel) and Primary Rate - PRI (1.544 and 2.048 Mbps).

Isotropic Antenna

A hypothetical omni-directional point-source antenna that serves as an engineering reference for the mea-surement of antenna gain.

ITU

International Telecommunication Union.

Jammer

An active electronic counter-measures (ECM) device designed to deny intelligence to unfriendly detectors or to disrupt communications.

JPEG

ISO Joint Picture Expert Group standard for the compression of still pictures.

Ka-Band

The frequency range from 18 to 31 GHz.

kbps

Kilobit per second.


Refers to transmission speed of 1,000 bits per second.

Kelvin (K) The temperature measurement scale used in the scientific community. Zero K represents absolute zero, and corresponds to minus 459 degrees Fahrenheit or minus 273 Celsius. Thermal noise characteristics of LNA are measured in Kelvin.

kHz

Kilohertz.

Refers to a unit of frequency equal to 1,000 Hertz.

Ku-Band

The frequency range from 10.9 to 17 GHz. This band has been split into two segments by the Federal Communications Commission. The first is the 11.7-12.2 GHz band known as FSS (Fixed Satellite Service), and there are 22 FSS Ku-Band satellites in orbit over North America today. They range in power from 20 to 60 watts per transponder, requiring a three to five foot antenna for clear reception. The 12.2-12.7 GHz segment is known as BSS (Broadcasting Satellite Service). Satellites in this band range in power from 100-200 watts per transponder, allowing the use of receiver antennas as small as 18 inches.

LAN

Local Area Network.

A data communications system that (a) lies within a limited spatial area, (b) has a specific user group, (c) has a specific topology, and (d) is not a public switched telecommunications network, but may be con-nected to one.

L-Band

The frequency range from 0.5 to 1.5 GHz. Also used to refer to the 950 to 1450MHz used for mobile com-munications.

Leased Line

A dedicated circuit typically supplied by the telephone company.

LEO

Low Earth Orbit.

Satellites placed in orbit less than 22,300 miles above the earth.

Line amplifier

Amplifier used in the middle of a network to re-amplify a signal.

Link Margin

The amount of signal in dB by which the satellite system exceeds the minimum levels required for opera-tion. This is usually determined by adding transmitter power and antenna gain, minus the path and transmission line losses.

LNA

Low Noise Amplifier.

A preamplifier usually mounted on a receiving dish antenna designed amplify weak signals and contribute the least amount of thermal noise to the received signal.


LNB

Low Noise Block converter.

A small device mounted at the focal point of a satellite dish which converts and amplifies high-frequency satellite signals into lower frequencies. The successor to the LNA.

LOS

1. Loss of Signal. The time or point when a satellite passes from being in line of sight of a ground station.

2. Line of Sight. If no obstruction (mountain, building,…) exists between the transmitter and receiver antenna.

Margin

The amount of signal in dB by which the satellite system exceeds the minimum levels required for opera-tion.

Megahertz (MHz) Refers to a frequency equal to one million Hertz, or cycles per second.

MEO

Medium Earth Orbit.

Microwave

Line-of-sight, point-to-point transmission of signals at high frequency. Many CATV systems receive some television signals from a distant antenna location with the antenna and the system connected by micro-wave relay. Microwaves are also used for data, voice, and indeed all types of information transmission. The growth of fiber optic networks have tended to curtail the growth and use of microwave relays.

Microwave Interference

Interference which occurs when an earth station aimed at a distant satellite picks up a second, often stronger signal, from a local telephone terrestrial microwave relay transmitter. Microwave interference can also be produced by nearby radar transmitters as well as the sun itself. Relocating the antenna by only several feet will often completely eliminate the microwave interference.

Modem

Acronym for MOdulator-DEModulator. A device that modulates and demodulates signals. Note: Modems are primarily used for converting digital signals into quasi-analog signals for transmission over analog communication channels and for reconverting the quasi-analog signals into digital signals.

Modulation

The process of manipulating the frequency or amplitude of a carrier in relation to an incoming video, voice or data signal.

Modulator

A device which modulates a carrier.

MPEG

The Moving Pictures Experts Group, the television industry's informal standards group.


MPEG-2

The agreed standard covering the compression of data (coding and encoding) for digital television.

MSS

Mobile Satellite Service.

Multicast Multicast is a subset of broadcast that extends the broadcast concept of one to many by allowing "the sending of one transmission to many users in a defined group, but not necessarily to all users in that group."

Multiplexing

Techniques that allow a number of simultaneous transmissions over a single circuit.

Noise

Any unwanted and unmodulated energy that is always present to some extent within any signal.

Noise Figure

A term which is a figure of merit of a device, such as an LNA or receiver, expressed in dB, which compares the device with a perfect device.

On-line

Electronic availability on demand from a computer-based system without mounting removable media such as magnetic tape or disks.

Outage

A telecommunication service condition wherein a user is deprived of service due to a malfunction of the communication system.

Packet In data communication, a grouping of a sequence of binary digits, including data and control signals, that is transmitted and switched as a composite whole. The data, control signals, and possibly error control in-formation, are arranged in a specific format. The packet can be of either fixed or variable length.

Packet Data

A process where stored data is transmitted in discrete units, called packets, allowing for more efficient use of channel capacity and reliability of transfer.

Packet mode

A packet switched operational mode for transferring (transporting and switching) user information through a network without establishing a connection. The packets do not necessarily arrive at their destination in the order they were sent, unlike the circuit mode of transmission. See packet switching.

Packet Switching

Data transmission method that divides messages into standard-sized packets for greater efficiency of routing and transport through a network.


Parabolic Antenna

A type of antenna which takes its name from the shape of the dish described mathematically as a parabo-la. The function of the parabolic shape is to focus the weak microwave signal hitting the surface of the dish into a single focal point in front of the dish. It is at this point that the feed horn is usually located.

Pass band

The frequency range over which the amplifier or transponder reproduces signals.

PCM

Pulse Code Modulation.

A time division modulation technique in which analog signals are sampled and quantized at periodic inter-vals into digital signals. The values observed are typically represented by a coded arrangement of 8 bits of which one may be for parity.

PCS

Personal Communications System.

PLL

Phase-Locked Loop.

A type of electronic circuit used to demodulate satellite signals.

Polar Mount Antenna mechanism permitting steering in both elevation and azimuth through rotation about a single axis. While an astronomer's polar mount has its axis parallel to that of the earth, satellite earth stations utilize a modified polar mount geometry that incorporates a declination offset.

Polar Orbit An orbit with its plane aligned in parallel with the polar axis of the earth.

Polarization

A technique used by the satellite designer to increase the capacity of the satellite transmission channels by reusing the satellite transponder frequencies. In linear cross polarization schemes, half of the trans-ponders beam their signals to earth in a vertically polarized mode; the other half horizontally polarize their down links. Although the two sets of frequencies overlap, they are 90 degree out of phase, and will not in-terfere with each other. To successfully receive and decode these signals on earth, the earth station must be outfitted with a properly polarized feed horn to select the vertically or horizontally polarized signals as desired.

In some installations, the feed horn has the capability of receiving the vertical and horizontal transponder signals simultaneously, and routing them into separate LNAs for delivery to two or more satellite television receivers. Unlike most domestic satellites, the Intelsat series use a technique known as left-hand and right-hand circular polarization.

Polarization offset angle

The angle from vertical that the LNB needs to be set at for maximum reception efficiency. The actual angle depends on the geographical location of the reception site.

Polarization Rotator

A device that can be manually or automatically adjusted to select one of two orthogonal polarizations.


Protocol Any set of standard procedures that permit devices to intercommunicate.

PSK

Phase Shift Keying.

A modulation technique that involves phase shifting the carrier to reflect a digital stream.

PSTN

Public Switched Telephone Network.

Any common carrier network that provides circuit switching among public users. Note: The term is usually applied to the public switched telephone network, but it could be applied more generally to other switched networks, e.g., packet switched public data networks.

PTT

Post Telephone and Telegraph Administration.

Refers to operating agencies directly or indirectly controlled by governments in charge of telecommunica-tions services in most countries of the world.

Pulse Code Modulation

A time division modulation technique in which analog signals are sampled and quantized at periodic inter-vals into digital signals. The values observed are typically represented by a coded arrangement of 8 bits of which one may be for parity.

QPSK

Quadrature Phase Shift Keying.

System of modulating a satellite signal.

Rain Outage

Loss of signal at Ku- or Ka-Band frequencies due to absorption and increased sky-noise temperature caused by heavy rainfall.

Receiver (Rx) An electronic device which enables a particular satellite signal to be separated from all others being re-ceived by an earth station, and converts the signal format into a format for video, voice or data.

Receiver Sensitivity

Expressed in dBm this tells how much power the detector must receive to achieve a specific baseband per-formance, such as a specified bit error rate or signal to noise ratio.

RFI Radio Frequency Interference.

A term used to denote apparent disturbance or distortion to satellite signals.

Router

Network layer device that determines the optimal path along which network traffic should be forwarded. Routers forward packets from one network to another based on network layer information.


S/N

Signal to Noise Ratio.

The ratio of the signal power and noise power. The better the signal to noise ratio, the better the quality of the signal.

Satellite

A sophisticated electronic communications relay station orbiting 22,237 miles above the equator moving in a fixed orbit at the same speed and direction of the earth (about 7,000 mph east to west).

Scalar Feed

A type of horn antenna feed which uses a series of concentric rings to capture signals that have been re-flected toward the focal point of a parabolic antenna.

SCPC

Single Channel Per Carrier.

An economical way to get multiple signals on one transponder.

Side lobe

Off-axis response of an antenna.

Simplex operation

That mode of operation in which communication between two points occurs in only one direction at a time. Contrast with half duplex or duplex operation.

Slot That longitudinal position in the geosynchronous orbit into which a communications satellite is "parked". Above the United States, communications satellites are typically positioned in slots which are based at two to three degree intervals.

Solar Outage

Solar outages occur when an antenna is looking at a satellite, and the sun passes behind or near the sa-tellite and within the field of view of the antenna. This field of view is usually wider than the beam width. Solar outages can be exactly predicted as to the timing for each site.

Spectrum

The range of electromagnetic radio frequencies used in transmission of voice, data and television.

Spillover

Satellite signal that falls on locations outside the beam pattern's defined edge of coverage.

Spin Stabilization

A form of satellite stabilization and attitude control which is achieved through spinning the exterior of the spacecraft about its axis at a fixed rate.

Splitter

A passive device (one with no active electronic components) which distributes a signal carried on a cable in two or more paths and sends it to a number of receivers simultaneously.


Spot Beam

A focused antenna pattern sent to a limited geographical area. Spot beams are used by satellites to deliv-er certain transponder signals to geographically well defined areas.

Spread Spectrum

The transmission of a signal using a much wider bandwidth and power than would normally be required. Spread spectrum also involves the use of narrower signals that are frequency hopped through various parts of the transponder. Both techniques produce low levels of interference Between the users. They also provide security in that the signals appear as though they were random noise to unauthorized earth sta-tions. Both military and civil satellite applications have developed for spread spectrum transmissions.

SSPA

Solid state power amplifier.

Stationkeeping

Minor orbital adjustments that are conducted to maintain the satellite's orbital assignment within the allo-cated "box" within the geostationary arc.

Sub carrier

A second signal "piggybacked" onto a main signal to carry additional information. In satellite television transmission, the video picture is transmitted over the main carrier. The corresponding audio is sent via an FM sub carrier. Some satellite transponders carry as many as four special audio or data sub carriers whose signals may or may not be related to the main programming.

TDM

Time Division Multiplexing.

Multiple users can receive their data on the same frequency. TDM avoids the intermodulation problem en-tirely as each user's signal is presented serially and the downlink transmitter can be more power efficient than FDM.

TDMA

Time Division Multiple Access.

Refers to a form of multiple access where a single carrier is the shared by many users. A method of ac-cessing a satellite using time separation; sending simultaneous data streams interleaved using a clock to separate the various data packets.

Terrestrial In communications parlance, this refers to Earth, land or ground-based telecommunications systems.

Transceiver

A combination of transmitter and receiver.

Transmitter

An electronic device consisting of oscillator, modulator and other circuits which produce a radio or televi-sion electromagnetic wave signal for radiation into the atmosphere by an antenna.

Transponder

A device located on board the satellite which receives signals up linked by a programmer and transmits them back to earth on a different frequency.


A combination of receiver, frequency converter, and transmitter package, physically part of a communica-tions satellite. TV Transponders have a typical output of 5 to 10 watts, operate over a frequency band with a 36 to 72 megahertz bandwidth in the L, C, Ku, and sometimes Ka Bands or in effect typically in the mi-crowave spectrum, except for mobile satellite communications. TV Communications satellites typically have between 12 and 24 onboard transponders although the INTELSAT VI at the extreme end has 50.

TT&C

Telemetry, Tracking and Control.

Means of accessing the control systems in a spacecraft in order to position and configure the spacecraft; or the facility which monitors and controls the health of a satellite.

TVRO

Television Receive Only.

Terminals that use antenna reflectors and associated electronic equipment to receive and process televi-sion and audio communications via satellite. Typically small home systems.

Tweeking

The process of adjusting an electronic receiver circuit to optimize its performance.

TWT (Traveling-wave tube) A microwave tube of special design using a broadband circuit in which a beam of electrons interacts conti-nuously with a guided electromagnetic field to amplify microwave frequencies.

TWTA (Traveling-wave-tube amplifier) A combination of a power supply, a modulator (for pulsed systems), and a traveling-wave tube, often packaged in a common enclosure.

UHF

Ultra High Frequency.

The band in the 500 to 900 MHz range, including TV channels 14 through 83.

Unicast A unicast application transmits a copy of every packet to every receiver.

Uplink

The transmitter and antenna system used to transmit signals from a ground station to a satellite. Also the frequency the satellite expects to receive transmissions.

The earth station used to transmit signals to a satellite.

USB

Universal Serial Bus.

Local communication network used to connect PC I/O devices to the host PC. The host communicates with the I/O devices by polling each device in a 1 ms (full speed) or 1/8 ms (high speed) cycle. The communi-cation link uses differential signaling over twisted pair wire at 1.5 MBPS (low speed) 12 MBPS (full speed) or 480 MBPS (high speed).

V.35

ITU-T standard describing a synchronous, physical layer protocol used for communications between a network access device and a packet network. V.35 is most commonly used in the United States and in Eu-rope, and is recommended for speeds up to 48 Kbit/s.


VC

Virtual Circuit.

A communication arrangement in which data from a source user may be passed to a destination user over various real circuit configurations during a single period of communication.

VHF

Very High Frequency.

The band in the 30 to 300 MHz range, including TV channels 2 through 13

VPN

Virtual Private Network.

A capability that allows users to create their own private information network.

VSAT

Very Small Aperture Terminal.

A means of narrowcast transmission of video, voice and data by SCPA means to a satellite, typically used in business applications.

VSWR

Voltage Standing Wave Ratio.

A measurement of mismatch in a cable, waveguide, or antenna system.

WAN

Wide Area Network.

Waveguide

A metallic microwave conductor, typically rectangular in shape, used to carry microwave signals into and out of microwave antennas.

X.25

A set of packet switching standards published by the CCITT.

WAVECOM EasySatSystem Software W61 v1.1 User Manual Index 29

Index

A

ADC 9 AFC 9 AGC 9 ALC 9 ALS 9 AM 9 Amplifier 9 Antenna 7, 8, 9 AOS 9 Aperture 9 Apogee 10 APRS 10 Asymmetric transmission 10 Asynchronous transmission 10 Attenuation 10 Availability 10 AZ/EL Mount 10 Azimuth 10

B

Backoff 10 Band Pass Filter 10 Bandwidth 10 Baseband 10 Baud 11 Beacon 11 Beam width 11 Bent Pipe Transponder 11 Bird 11 Bit 11 Bit Error Rate 11 Bit Rate 11 Block Down Converter 11 BPSK 11 Broad beam 12 Broadcast 12 Byte 12

C

C/N 12 C/T 12 Call 12 Carrier 12 Carrier Frequency 12 C-Band 12 CDMA 12 Channel 12 Circuit mode 12 Clarke Belt 13 Cliff effect 13

Codec 13 Co-Location 13 Company Profile 1 Compression 13

D

Data 13 dB 13 dBi 13 DBS 13 dBW 13 Delay 13 Demodulation 14 Demodulator 14 DES 14 Deviation 14 Digital 14 Digital data 14 Digital voice 14 Digitize 14 Dish 14 Dish antenna 8 Downconverter 8 Downlink 14 DSP 14 Duplex Transmission 14 DVB 14

E

E1 15 E3 15 Earth Station 15 Echo Canceller 15 Edge of Coverage 15 EIRP 15 Elevation 15 Encrypt 15 EOL 15 Equatorial Orbit 15 Error Handling 7

F

F/D 15 FDMA 15 FEC 16 Feed 16 Feed horn 16 FM 16 Focal Length 16 Focal Point 16 Footprint 16 Forward path 16 FPGA 16 Frequency 16 Frequency Coordination 16 FTP 17 Full-duplex operation 17

30 Index WAVECOM EasySatSystem Software W61 v1.1 User Manual

G

G/T 17 Gain 17 GAN 17 Gateway 17 General Description of the components 7 Geostationary 17 Geosynchronous Orbit (GSO) 17 GHz 17 Global Beam 17 Glossary of Terms 9 GMDSS 18 GPS 18

H

Half-duplex operation 18 Hardware Recommendations 7 HGS 18 High Power Amplifier (HPA) 18 Hub 18 Hybrid satellite 18 Hz 18

I

IBS 18 Inclination 18 INMARSAT 18 Installation 2 Interference 19 Intermodulation 19 Internetworking 19 Introduction 1 IRIDIUM 19 ISDN 19 Isotropic Antenna 19 ITU 19

J

Jammer 19 JPEG 19

K

Ka-Band 19 kbps 19 Kelvin (K) 20 kHz 20 Ku-Band 20

L

LAN 20 L-Band 20 Leased Line 20 LEO 20 Line amplifier 20 Link Margin 20 LNA 20 LNB 21

Loopyagi (low cost solution) 8 LOS 21

M

Margin 21 Megahertz (MHz) 21 MEO 21 Microwave 21 Microwave Interference 21 Modem 21 Modulation 21 Modulator 21 MPEG 21 MPEG-2 22 MSS 22 Multicast 22 Multiplexing 22

N

Noise 22 Noise Figure 22

O

On-line 22 Operation 6 Outage 22 Overview 7

P

Packet 22 Packet Data 22 Packet mode 22 Packet Switching 22 Parabolic Antenna 23 Pass band 23 PC 8 PC with W61PC(s) 8 PCM 23 PCS 23 PLL 23 Polar Mount 23 Polar Orbit 23 Polarization 23 Polarization offset angle 23 Polarization Rotator 23 Professional Version 1 Protocol 24 Proven Components 8 PSK 24 PSTN 24 PTT 24 Pulse Code Modulation 24

Q

QPSK 24

WAVECOM EasySatSystem Software W61 v1.1 User Manual Index 31

R

Rain Outage 24 Receiver (Rx) 24 Receiver Sensitivity 24 References 2 Revisions 2 RFI 24 Router 24

S

S/N 25 Satellite 25 Scalar Feed 25 SCPC 25 Setup 3 Side lobe 25 Simplex operation 25 Slot 25 Software 2 Solar Outage 25 Source 7 Source Code 1 Spectrum 25 Spillover 25 Spin Stabilization 25 Splitter 25 Spot Beam 26 Spread Spectrum 26 SSPA 26 Stationkeeping 26 Sub carrier 26

T

TDM 26 TDMA 26 Terrestrial 26 Training 1 Transceiver 26 Transmitter 26 Transponder 26 TT&C 27 TVRO 27 Tweeking 27 TWT (Traveling-wave tube) 27 TWTA (Traveling-wave-tube amplifier) 27

U

UHF 27 Unicast 27 Uplink 27 USB 27

V

V.35 27 VC 28 VHF 28 VPN 28 VSAT 28

VSWR 28

W

WAN 28 Waveguide 28 Welcome 1

X

X.25 28

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