Overview

Satellite communication systems are now a major part of most telecommunications networks as well as every-day lives through mobile personal communication systems and broadcast television. A fundamental understanding of such systems is therefore important for a wide range of system designers, engineers and users.

This book is focused on the fundamental principles underlying satellite communication systems, treating each with sufficient depth to provide a balanced overview of the constituent system elements.

This satellite communications book is used as a text for a number of professional education and university courses, as well as for a number of in-house courses. In particular, it is complimentary to attendees on the edVirtus Satellite Communications—Overview, Satellite Communications—Intermediate, and Satellite Communications—Advanced training courses delivered by the author Dr Mike Ryan.

Preface

Satellite communication systems are now a major part of most telecommunications networks as well as our every-day lives through mobile personal communication systems and broadcast television. A sound understanding of such systems is therefore important for a wide range of system designers, engineers and users.

This book is focused on the fundamental principles underlying satellite communication systems, treating each with sufficient depth to provide a balanced overview of the constituent system elements. While particular systems are discussed briefly by way of example, detailed descriptions of commercial systems are not included since they are constantly changing and are also described in considerable detail at the system level elsewhere in a number of excellent texts (see Appendix A for a selected bibliography). This book is intended to equip the reader with the sound background knowledge to be able to understand and evaluate such systems. While some familiarity with basic mathematics and communications theory is an advantage, the concepts have been explained at a level that is accessible to a wide range of readers.

There are nine chapters. Chapter 1 provides an introduction to satellite communications, a little history, a description of the space environment, and an outline of basic satellite operation. Chapter 2 addresses the various forms of satellite orbit used for satellite communications and Chapter 3 considers the frequencies used for Earth-space communications as well as a brief discussion of interference issues. Chapter 4 examines propagation with regard to the losses incurred in the uplink and downlink. Chapter 5 discusses the antennas utilised for communications as well as for control of satellite functions. Modulation and multiplexing are the focus of Chapter 6, which describes how baseband signals are translated in frequency to occupy the satellite channel and how signals are combined at the Earth terminal to share the portion of the channel that has been allocated to that station. Since the satellite channel has a very large attenuation and contains channel impairments such as noise, channel coding is the subject of Chapter 7. Chapter 8 then addresses the multiple-access techniques by which geographically separate Earth stations can share the bandwidth available from a satellite transponder. In Chapter 9 we put all these aspects together and consider the link-budget calculations required to make use of a satellite-communications system.

Table of contents

CONTENTS
1	INTRODUCTION	1
1.1	Introduction	1
1.2	Advantages / Disadvantages	2
1.3	History of Satellites	4
1.4	The Space Environment	9
1.5	Basic Satellite Operation	14
1.6	Satellite Subsystems	15
1.7	Revision Questions	24
2	ORBITS	27
2.1	Introduction	27
2.2	Physical Laws	29
2.3	Choice Of Orbital Parameters	31
2.4	Circular Orbits	32
2.5	Orbital Perturbations	34
2.6	Orbit Height	37
2.7	Satellite Ground Traces	44
2.8	Satellite Launch	46
2.9	Orbital Manoeuvring	50
2.1	Footprint	51
2.11	Look Angles	53
2.12	Solar Eclipses	57
2.13	Revision Questions	59
3	FREQUENCIES	61
3.1	Introduction	61
3.2	Satellite Frequency Bands	65
3.3	Interference	69
3.4	Revision Questions	74
4	PROPAGATION	75
4.1	Introduction	75
4.2	The Electromagnetic Wave	76
4.3	Space-Wave Communications	77
4.4	Transmission Path Losses	81
4.5	Propagation for Mobile-Satellite Channels	91
4.6	Revision Questions	92
5	ANTENNAS	95
5.1	Introduction	95
5.2	An Isotropic Radiator	95
5.3	Antenna Properties	96
5.4	Antennas for Satellite Communications	99
5.5	Pointing Error and Tracking Systems	110
5.6	Revision Questions	112
6	MODULATION & MULTIPLEXING	113
6.1	Introduction	113
6.2	Analogue Modulation	114
6.3	Digital Signals	125
6.4	Digital Modulation	132
6.5	Multiplexing	140
6.6	A Comparison Of FDM and TDM	148
6.7	Revision Questions	149
7	CHANNEL CODING	151
7.1	The Reason For Channel Coding	151
7.2	Channel Coding in Satellite Communications	154
7.3	Basic Elements of Coding	155
7.4	Block Codes	158
7.5	Convolutional Codes	170
7.6	Interleaving	176
7.7	Concatenated Codes	177
7.8	Turbo Codes	177
7.9	Automatic-Repeat-Request (ARQ) Schemes	177
7.1	Coding Gain	178
7.11	Comparison of Codes	178
7.12	Channel Coding in Satellite Communications	180
7.13	Revision Questions	181
8	MULTIPLE ACCESS	183
8.1	Frequency-Division Multiple Access	185
8.2	Time-Division Multiple Access	193
8.3	Code-Division Multiple Access	201
8.4	Frequency Hopping	204
8.5	Time Hopping	206
8.6	Hybrid Techniques	208
8.7	Revision Questions	209
9	LINK BUDGET ANALYSIS	211
9.1	Introduction	211
9.2	Models for the Major Elements of the Satellite Communications System	211
9.3	Link Budget Parameters	214
9.4	Satellite System Link Equations	220
9.5	Link Budget Example	222
9.6	Link Budget Analysis Template	226
9.7	Revision Questions	227
	INDEX	229

Sample Chapter

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