SATELLITE COMMUNICATIONS TECHNOLOGY v

ContentsAbout the Author iIntroduction iiHow This Book Is Organised iii

Introduction to Satellite Communications

1 Uses of Communications Satellites 3An Alternative Solution 6Available Services 6

Fundamentals of Satellite Communications

2 Satellite Basics 9Maturity of the Technology 9

3 Satellite Configuration 11The Geostationary Communications Satellite 12The Low and Medium Earth Orbit Communications Satellite 13Typical Current Spacecraft Bus Characteristics 15

4 Launching Satellites 16Rocket Basics 16Multistage Rockets 17Liquid Stage 17Liquid Propellants 18Solid Boosters 18

5 Satellite Orbits 20Mathematical Background 20

Kepler's Laws 21Newton's Laws 22Co-ordinate Systems 22Classical Orbital Elements 23

Uses of Different Orbits 24The Geostationary Orbit 25

Advantages of the Geostationary Orbit 26Disadvantages of the Geostationary Orbit 27

Other Orbits 27Semi Synchronous Orbits 27Low Earth Orbits (LEO) 27Big LEO and Little LEO 28Medium Earth Orbits (MEO) 28Intermediate Circular Orbits (ICO) 28Highly Elliptical Orbits (HEO) 28

Comparison of Orbits for Communications 28

6 Geometrical Relationships for Geostationary Orbit 30Slant Range 30Azimuth and Elevation 31Elevation 31

vi SATELLITE COMMUNICATIONS TECHNOLOGY

Azimuth 32Polarisation Angle 33

7 The Satellite Link 34Transparent Repeaters 34

Terminology 34Payload Configuration 35

On Board Processing 35Payload Configuration 36

Intersatellite Links 37Store and Forward Messaging 37

Payload Configuration 38Transmission Frequencies 38The Satellite Connection 41Comparison of Terrestrial and Satellite Repeaters 41Factors Affecting Performance 42The Link Equation 43Antenna Gain 43EIRP 44PFD 45G/T 45Polarisation 45Space Loss 47Atmospheric Losses 47Attenuation By Atmospheric Gases 48Attenuation By Hydrometeors 49

8 Noise and Interference 54Noise 54

Thermal Noise 55Noise Temperature 55System Temperature 56Excess Input Noise Temperature 56Noise Factor 57Noise Figure 57Noise Sources In Series 58

Calculations With Noise 59Antenna Temperature 59Overall System Temperature 59

Natural Radio Emissions 60Extra-terrestrial Sources 61Lunar Noise 61Galactic Noise And The Cosmic Background 61Radio Stars 62Atmospheric Sources 63Noise From The Surface Of The Earth 63

Interference 63Intermodulation 64Co-Channel Interference 65Adjacent Channel Interference 65Cross Polar Interference 65

9 Link Performance Objectives 67

SATELLITE COMMUNICATIONS TECHNOLOGY vii

Availability 67Quality Objectives for Digital Telephony 67Quality Objectives for Data Transfer 67Availability Objectives for Telephony 68Propagation Time for Telephony 68

10 Link Budget 69The Earth to Space Link (Uplink) 70The Space to Earth Link (Downlink) 71Composite Performance 71

11 Modulation, Access and Coding 73Baseband Signals 73

Voice 74Television 74Data 74

Baseband Modulation 75Source Coding 75Pulse Code Modulation (PCM) 75Differential PCM (DPCM) 76Adaptive Differential PCM (ADPCM) 76Video Compression 76

RF Modulation 77Phase Shift Keying (PSK) 78Quadrature Amplitude Modulation (QAM) 80

Multiplexing 82Time Division Multiplexing (TDM) 82

Error Detection and Coding 82Forward Error Correction (FEC) 82Automatic Repeat Request (ARQ) 84

Spread Spectrum 85Multiple Access Techniques 85

Frequency Division Multiple Access (FDMA) 86Single Channel Per Carrier (SCPC) 87Time Division Multiple Access (TDMA) 87MF-TDMA 89ALOHA 89Code Division Multiple Access (CDMA) 90

DVB-S and DVB-S2 91DVB RCS 93Capacity Assignment 93Data Transmission Over Satellite 94

Terrestrial Protocols 94Housekeeping Messages On Terrestrial Protocols 95Spoofing 95Packet Compression 96

12 Communications Satellite Technology 98Payload Configuration 98

Regenerative Payloads 99High Throughput Satellites (HTS) 100Geostationary Satellite Payload Mechanical Configuration 100Non-Geostationary Satellite Payload Mechanical Configuration 101

Coverage Patterns 101

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Global Beams 102Spot Beams 102Contoured Beams 103Service, Coverage and Beam Areas 103

Reliability and Redundancy 104Redundancy 104

13 Earth Station Technology 106Antenna Subsystem 109

Reflector Antenna Geometry 111Antenna Performance 111Antenna Beams and Sidelobes 112Antenna Mounts 114Equatorial Mountings For DBS and DTH Reception 115Altazimuth Mounting For Small to Medium Sized Antennas 116

Feed Assembly 117Feed Horns 117Feed Supports 118

Tracking 118Monopulse Tracking 120Step Tracking 120Program Tracking 120Manual Tracking 120

Stabilisation 121Radomes 121

Air Supported Radome 121Rigid Shell Radome 122Space Frame Radome 122

Low Noise Block 122Frequency Converters 123Modulators, Demodulators and Modems 123High Power Amplifiers 124

The Travelling Wave Tube Amplifier 124The Klystron Amplifier 125The Solid State Power Amplifier 125

Lineariser 125Carrier Combining 126Block Upconverter (BUC) 126Cross Site Interfaces 126Redundancy Switching 127Improving the Link 128

Adaptive Coding and Modulation 128Dynamic Pre-Distortion (DPD) 128Adaptive Carrier Cancellation 128Automatic Uplink Power Control 129Meta Carrier 129VoIP Over Satellite 129

Communications Services

14 Introduction to Communications Services 13315 Network Topology 13416 Fixed and Mobile Networks 137

SATELLITE COMMUNICATIONS TECHNOLOGY ix

VSAT Services

17 Introduction to VSAT Services 141VSATs and High Throughput Satellites 142VSATs and Mobile Terminals 143VSATs and MEO Satellites 143

18 Interactive VSATs 144Overview of Technology 144Virtual Subnetworks and Shared Hub Networks 145Network Management 146TDM/MF-TDMA Interactive VSAT Networks 147

Hub Station 149Remote Terminals 151

Demand Assigned SCPC Interactive VSAT Networks 152CDMA Interactive VSAT Networks 153Hybrid Networks 153Remote Terminal Diversity 153

19 Meshed VSATs 156Overview of Technology 156DAMA SCPC Meshed VSAT Networks 159

Typical DAMA SCPC Meshed VSAT Signalling Channel Data Formats 160Terminals 161

TDM SCPC Meshed VSAT Networks 162Terminals 163

TDMA Meshed VSAT Networks 163MF TDMA Meshed Network Transmissions 165Terminals 165

TDM/MF-TDMA Interactive VSATs 165

20 Point To Point Links 166Overview of Technology 166Network Monitoring and Control 168Redundancy Switching 169Point To Point Links in Star and Meshed VSAT Networks 169Topologies Built From Multiple Point To Point Links 169

21 Data Broadcast 172Overview of Technology 172Hub Station 173Remote Terminals 174

22 Internet Access 175Internet Access Using Interactive VSATs 176Internet Access Using Data Broadcast 177

23 Internet Trunking 17924 Telephony 181

Telephony Using Interactive VSATs 181Telephony Using Meshed VSATs 182Telephony On Point To Point Links 182

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25 Cellular Backhaul 18426 Digital Cinema 186

Overview of Technology 186Live Events 187

Mobile Services

27 Introduction to Mobile Services 191Network Configuration 192

28 Inmarsat 194Satellites 194

Inmarsat-3 194Inmarsat-4 195Inmarsat-5 195

Ground Network 195Gateway Earth Station Locations 195Coverage 196Services Offered 198

Global Xpress Services 198BGAN Services 198BGAN M2M Services 199Voice Services 199Legacy Services 199

Global Xpress Services 200Network Configuration 200Signal Types and Characteristics 200User Terminals 201

BGAN Services 201Network Configuration 202Signal Types and Characteristics 203User Terminals 203

BGAN M2M Services 203User Terminals 203

Voice Services 204Network Configuration 204Signal Types and Characteristics 204User Terminals 204

Legacy SCPC Voice and Data Services 204Network Configuration 206Signal Types and Characteristics 206

29 Thuraya 208Satellites 208Ground Network 208Gateway Earth Station Locations 208Ground Control Network Facility Locations 209Coverage 209Services Offered 209Network Configuration 210Signal Types and Configuration 210User Terminals 211

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30 Iridium 212Satellites 212Ground Network 212Gateway Earth Station Locations 213Ground Control Network Facility Locations 213Coverage 213Services Offered 214Network Configuration 214Signal Types and Configuration 215User Terminals 216

31 Globalstar 217Satellites 217Ground Network 217Gateway Earth Station Locations 217Ground Control Network Facility Locations 219Coverage 220Services Offered 220Network Configuration 221Signal Types and Configuration 221User Terminals 222

32 Orbcomm 223Satellites 223Ground Network 223Gateway Earth Station Locations 224Ground Control Network Facility Locations 224Coverage 225Services Offered 225Network Configuration 225Signal Types and Configuration 226User Terminals 227

33 Handheld Voice and Data Services 22834 Fixed Voice and Data Services 23035 Portable Voice and Data Services 23236 Land Mobile Services 23537 Maritime Services 23838 Aeronautical Services 24239 Train Communications 24640 M2M 24841 Search and Rescue 250

Cospar-Sarsat 250Commercial Emergency Reporting Services 251User Terminals 251

EPIRBs 251ELB / ELTs 252PLBs 252SENDs 253

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Broadcast TV and Radio

42 Introduction to Broadcast TV and Radio 25743 Direct To Home Broadcasting 258

DBS and DTH 258TV and Radio Broadcasting 258Network Configuration 259Signal Types and Characteristics 260Uplink Earth Stations 260Consumer Satellite TV Receivers 262

44 Reception By Cable Heads 263CATV 263SMATV 263

45 Satellite News Gathering (SNG) 266Network Configuration 266Signal Types and Characteristics 267Flyaway Terminals 267SNG Vans 269

46 Contribution and Distribution 271Transmission To Broadcast Centres 271

Network Configuration 271Signal Types and Characteristics 272Terminals 272

Distribution of Digital Terrestrial TV 273Radio Distribution to Local Radio Stations 274

Positioning, Tracking and Timing

47 Introduction to Positioning, Tracking and Timing 27748 Positioning and Timing 27849 Augmentation 279

Augmentation Systems For Aviation 279StarFire 280OmniStar 280

50 Tracking 281Personal Tracking 281Asset Tracking 282Statutory Tracking 282

Annexes

Annex 1 Glossary 287Annex 2 Abbreviations 315

SATELLITE COMMUNICATIONS TECHNOLOGY xiii