Satellite Communications E-Book

Timothy Pratt

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 1707

Veröffentlichungsjahr: 2019

Beschreibung

Extensive revision of the best-selling text on satellite communications — includes new chapters on cubesats, NGSO satellite systems, and Internet access by satellite

There have been many changes in the thirty three years since the first edition of Satellite Communications was published. There has been a complete transition from analog to digital communication systems, withanalog techniques replaced by digital modulation and digital signal processing. While distribution of television programming remains the largest sector of commercial satellite communications, low earth orbit constellations of satellites for Internet access are set to challenge that dominance.

In the third edition, chapters one through three cover topics that are specific to satellites, including orbits, launchers, and spacecraft. Chapters four through seven cover the principles of digital communication systems, radio frequency communications, digital modulation and multiple access techniques, and propagation in the earth’s atmosphere, topics that are common to all radio communication systems. Chapters eight through twelve cover applications that include non-geostationary satellite systems, low throughput systems, direct broadcast satellite television, Internet access by satellite, and global navigation satellite systems. The chapter on Internet access by satellite is new to the third edition, and each of the chapters has been extensively revised to include the many changes in the field since the publication of the second edition in 2003. Two appendices have been added that cover digital transmission of analog signals, and antennas.

An invaluable resource for students and professionals alike, this book:

• Focuses on the fundamental theory of satellite communications
• Explains the underlying principles and essential mathematics required to understand the physics and engineering of satellite communications
• Discusses the expansion of satellite communication systems in areas such as direct-broadcast satellite TV, GPS, and internet access
• Introduces the rapidly advancing field of small satellites, referred to as SmallSats or CubeSats
• Provides relevant practice problems based on real-world satellite systems

Satellite Communications is required reading for undergraduate and postgraduate students in satellite communications courses and an authoritative reference for engineers working in communications, systems and networks, and satellite operations and management.

Leseprobe

Satellite Communications

Timothy Pratt

Emeritus Professor of Electrical and Computer Engineering, Virginia Tech, Virginia, USA

Jeremy Allnutt

Emeritus Professor of Electrical and Computer Engineering, George Mason University Virginia, USA

Third Edition

This edition first published 2020© 2020 John Wiley & Sons Ltd

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The right of Timothy Pratt and Jeremy Allnutt to be identified as the author(s) of this work has been asserted in accordance with law.

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Library of Congress Cataloging-in-Publication Data:

Names: Pratt, Timothy, author. | Allnutt, J. (Jeremy), author.Title: Satellite communications / Timothy Pratt, Jeremy Allnutt.Description: 3rd edition. | Hoboken, NJ : Wiley, 2020. | Includes bibliographical references and index. |Identifiers: LCCN 2019015618 (print) | LCCN 2019018672 (ebook) | ISBN 9781119482147 (Adobe PDF) | ISBN 9781119482055 (ePub) | ISBN 9781119482178 (hardback)Subjects: LCSH: Artificial satellites in telecommunication. | Artificial satellites in telecommunication–Problems, exercises, etc. | Telecommunication–Problems, exercises, etc.Classification: LCC TK5104 (ebook) | LCC TK5104 .P725 2020 (print) | DDC 621.382/5–dc23LC record available at https://lccn.loc.gov/2019015618

Cover Design: WileyCover Image: © 2018 Intelsat, S.A. and its affiliates. All rights reserved.

This book is dedicated to our wives,Maggie and Norma, in gratitude for their love and support for over 50 years.

CONTENTS

Cover

Preface

About the Authors

1 Introduction

1.1 Background

1.2 A Brief History of Satellite Communications

1.3 Satellite Communications in 2018

1.4 Overview of Satellite Communications

1.5 Summary

1.6 Organization of This Book

References

2 Orbital Mechanics and Launchers

2.1 Introduction

2.2 Achieving a Stable Orbit

2.3 Kepler's Three Laws of Planetary Motion

2.4 Describing the Orbit of a Satellite

2.5 Locating the Satellite in the Orbit

2.6 Locating the Satellite With Respect to the Earth

2.7 Orbital Elements

2.8 Look Angle Determination

2.9 Orbital Perturbations

2.10 Orbit Determination

2.11 Space Launch Vehicles and Rockets

2.12 Placing Satellites Into Geostationary Orbit

2.13 Orbital Effects in Communications Systems Performance

2.14 Manned Space Vehicles

2.15 Summary

Exercises

References

3 Satellites

3.1 Satellite Subsystems

3.2 Attitude and Orbit Control System (AOCS)

3.3 Telemetry, Tracking, Command, and Monitoring (TTC&M)

3.4 Power Systems

3.5 Communications Subsystems

3.6 Satellite Antennas

3.7 Equipment Reliability and Space Qualification

3.8 Summary

Exercises

References

4 Satellite Link Design

4.1 Introduction

4.2 Transmission Theory

4.3 System Noise Temperature and G/T Ratio

4.4 Design of Downlinks

4.5 Ku-Band GEO Satellite Systems

4.6 Uplink Design

4.7 Design for Specified CNR: Combining CNR and C/I Values in Satellite Links

4.8 System Design for Specific Performance

4.9 Summary

Exercises

References

5 Digital Transmission and Error Control

5.1 Digital Transmission

5.2 Implementing Zero ISI Transmission in the Time Domain

5.3 Probability of Error in Digital Transmission

5.4 Digital Transmission of Analog Signals

5.5 Time Division Multiplexing

5.6 Packets, Frames, and Protocols

5.7 Error Control

5.8 Summary

Exercises

References

6 Modulation and Multiple Access

6.1 Introduction

6.2 Digital Modulation

6.3 Multiple Access

6.4 Frequency Division Multiple Access (FDMA)

6.5 Time Division Multiple Access (TDMA)

6.6 Synchronization in TDMA Networks

6.7 Transmitter Power in TDMA Networks

6.8 Star and Mesh Networks

6.9 Onboard Processing

6.10 Demand Assignment Multiple Access (DAMA)

6.11 Random Access (RA)

6.12 Packet Radio Systems and Protocols

6.13 Code Division Multiple Access (CDMA)

6.14 Summary

Exercises

References

7 Propagation Effects and Their Impact on Satellite-Earth Links

7.1 Introduction

7.2 Propagation Phenomena

7.3 Quantifying Attenuation and Depolarization

7.4 Propagation Effects That Are Not Associated With Hydrometeors

7.5 Rain and Ice Effects

7.6 Prediction of Rain Attenuation

7.7 Prediction of XPD

7.8 Propagation Impairment Countermeasures

7.9 Summary

Exercises

References

8 Low Throughput Systems and Small Satellites

8.1 Introduction

8.2 Small Satellites

8.3 Operational Use of SmallSats

8.4 Low Throughput Mobile Communications Satellite Systems

8.5 VSAT Systems

8.6 Signal Formats

8.7 System Aspects

8.8 Time Over Coverage

8.9 Orbital Debris

8.10 Summary

Exercises

References

9 NGSO Satellite Systems

9.1 Introduction

9.2 Orbit Considerations

9.3 Coverage and Frequency Considerations

9.4 System Considerations

9.5 Operational and Proposed NGSO Constellation Designs

9.6 System Design Example

9.7 Summary

Exercises

References

10 Direct Broadcast Satellite Television and Radio

10.1 C-Band and Ku-Band Home Satellite TV

10.2 Digital DBS-TV

10.3 DVB-S and DVB-S2 Standards

10.4 DBS-TV System Design

10.5 DBS-TV Link Budget for DVB-S and DVB-S2 Receivers

10.6 Second Generation DBS-TV Satellite Systems Using DVB-S2 Signal Format

10.7 Master Control Station and Uplink

10.8 Installation of DBS-TV Antennas

10.9 Satellite Radio Broadcasting

10.10 Summary

Exercises

References

11 Satellite Internet

11.1 History of Satellite Internet Access

11.2 Geostationary Satellite Internet Access

11.3 NGSO Satellite Systems

11.4 Link Budgets for NGSO Systems

11.5 Packets and Protocols for NGSO Systems

11.6 Gateways, User Terminals, and Onboard Processing Satellites

11.7 Total Capacity of OneWeb and SpaceX Proposed NGSO Constellations

11.8 End of Life Disposal of NGSO Satellites

11.9 Comparison of Spot Beam Coverage of GSO and LEO Internet Access Satellites

11.10 User Terminal Antennas for Ku-Band, Ka-Band, and V-Band

11.11 Summary

Exercises

References

12 Satellite Navigation and the Global Positioning System

12.1 The Global Positioning System

12.2 Radio and Satellite Navigation

12.3 GPS Position Location Principles

12.4 GPS Codes and Frequencies

12.5 Satellite Signal Acquisition

12.6 GPS Signal Levels

12.7 GPS Navigation Message

12.8 GPS C/A Code Standard Positioning System Accuracy

12.9 Differential GPS

12.10 Denial of Service: Jamming and Spoofing

12.11 ADS-B and Air Traffic Control

12.12 GPS Modernization

12.13 Summary

Exercises

References

Glossary

Appendix A Decibels in Communications Engineering

Appendix B Antennas

B.1 Introduction

B.2 Gain and Beamwidth

B.3 Polarization

B.4 Low Gain, Medium Gain, and High Gain Antennas

B.5 Small Antennas

B.6 Reflector Antennas

B.7 Antenna Theory

B.8 Multiple Beam Antennas

B.9 Phased Arrays

B.10 Phase Shifters

References

Acknowledgment

Appendix C Complementary Error Function erfc(

x

) and Q Function Q(

z

)

C.1 Equivalence Formulas and Tables of Values

References

Appendix D Digital Transmission of Analog Signals

D.1 Sampling

D.2 Bandpass Sampling

D.3 Digital Transmission

D.4 Nonuniform Quantization: Compression and Expansion

D.5 Reducing the Bandwidth of Digital Signals

References

Index

End User License Agreement

List of Tables

Chapter 1

Table 1.1

Chapter 2

Table 2.1

Table 2.2

Table 2.3

Table 2.4

Table 2.5

Table 2.6

Table 2.7

Table 2.8

Table 2.9

Table 2.10

Chapter 4

Table 4.1

Table 4.2

Table 4.3

Table 4.4

Table 4.5a

Table 4.5b

Table 4.6a

Table 4.6b

Table 4.7

Table 4.8a

Table 4.8b

Table 4.8c

Table 4.8d

Table 4.9a

Table 4.9b

Table 4.9c

Table 4.9d

Table 4.9e

Chapter 5

Table 5.1

Table 5.2

Table 5.3

Table 5.4

Chapter 6

Table 6.2

Table 6.3

Table 6.4

Table 6.5

Table 6.6

Table 6.7

Table 6.8

Table 6.1

Chapter 7

Table 7.1

Table 7.2

Table 7.3

Chapter 8

Table 8.1

Table 8.2

Table 8.3

Table 8.4

Table 8.5

Table 8.6

Table 8.7

Table 8.8

Chapter 9

Table 9.1

Table 9.2

Table 9.3

Table 9.4

Table 9.5

Table 9.6

Table 9.7

Table 9.8

Table 9.9

Table 9.10a

Table 9.10b

Table 9.10c

Chapter 10

Table 10.1

Table 10.2

Table 10.3

Table 10.4

Table 10.5

Table 10.6

Table 10.7

Table 10.8

Chapter 11

Table 11.1

Table 11.2

Table 11.3

Table 11.4

Table 11.5

Table 11.6

Chapter 12

Table 12.1

Table 12.2

Table 12.3

Table 12.4

Table 12.5

Chapter appendix b

Table B.1

Chapter appendix d

Table D.1

List of Illustrations

Chapter 1

Figure 1.3 Illustration of different application of satellites. (a) One way satellite link...

Chapter 2

Figure 2.1 Forces acting on a satellite in a stable orbit around the earth. Gravitational ...

Figure 2.2 The initial coordinate system used to describe the relationship between the ear...

Figure 2.3 The orbital plane coordinate system. In this coordinate system the orbital plan...

Figure 2.4 Polar coordinate system in the plane of the satellite's orbit. The axis

z

0

...

Figure 2.5 Illustration of Kepler's second law of planetary motion. A satellite is in orbi...

Figure Ex 2.2 The elliptical orbit of the satellite in Example 2.2. This is a Molniya orbit.

Figure 2.6 The orbit as it appears in the orbital plane. The point

O

is the center of th...

Figure 2.7 The circumscribed circle and the eccentric anomaly

E

. Point

O

is the center...

Figure 2.8 The geocentric equatorial system. This geocentric system differs from that show...

Figure 2.9 Locating the orbit in the geocentric equatorial system. The satellite penetrate...

Figure 2.10 The definition of elevation (

El

) and azimuth (

Az

). The elevation angle is m...

Figure 2.11 Zenith and Nadir pointing directions. The line joining the satellite and the ce...

Figure 2.12 The geometry of elevation angle calculation. The plane of the paper is the plan...

Figure 2.13 The geometry of the visibility calculation. The satellite is said to be visible...

Figure 2.14 Relationship between the orbital planes of the sun, moon, and earth. The plane ...

Figure 2.15 Launch sequence of a Proton rocket. After (Walsh and Groves 1997).

Figure 2.16 Launch vehicle market price versus performance, 1996 prices. After (Walsh and G...

Figure 2.17 Schematic of the decision-making process to select a rocket for a given satelli...

Figure 2.18 Illustration of transfer to geostationary orbit using an apogee kick motor (AKM...

Figure 2.19 Illustration of slow orbit raising technique to geostationary orbit using an io...

Figure 2.20 Illustration of an eclipse for a GEO satellite. The earth's shadow passes over ...

Figure 2.21 Dates and duration of eclipses for a GEO satellite. The longest period that the...

Figure 2.22 Illustration of a sun transit outage. During eclipse periods the sun will appea...

Chapter 3

Figure 3.2 Forces on a satellite in geosynchronous orbit. GEO satellites tend to drift aro...

Figure 3.3a Spinner satellites launched or operated by Intelsat between 1965 and 2013. Inte...

Figure 3.3b A typical spinner satellite from the 1980s. The entire satellite rotated at rou...

Figure 3.4 (a) Definition of pitch, roll, and yaw for a geostationary satellite. (b) Relat...

Figure 3.5 Attitude control system for a three-axis stabilized GEO satellite. The sun and ...

Figure 3.6 Geosynchronous satellite in an inclined orbit. Thrusters must be used to give t...

Figure 3.7 Simplified orbital control system. The sun and star sensors and the GPS receive...

Figure 3.8 Simplified diagram of the earth based control system for a GEO satellite. The m...

Figure 3.9a Example of a system of 24 transponders for a 6/4 GHz satellite operated with or...

Figure 3.9b Frequency plan for the transponders in Figure 3.9a. Note that there is a 20 MHz...

Figure 3.10 (a) Simplified diagram showing the communication system of a typical Intelsat s...

Figure 3.11 Simplified diagram of a bent pipe transponder for the 6/4 GHz band. The mixer a...

Figure 3.12 Double frequency conversion bent pipe transponder for the 14/11 GHz band. The u...

Figure 3.13 Onboard processing (OBP) transponder with multiple beam antennas. The processor...

Figure 3.14 Typical satellite antenna patterns and coverage zones. A global beam is 17° wid...

Figure 3.15 Contours of a circular spot beam serving Western Europe from a satellite locate...

Figure 3.17 Bathtub curve for probability of failure. The burn-in period is also referred t...

Figure 3.18 Redundancy connections. Each block

R

is a device with known reliability. (a) ...

Figure 3.19 Redundant TWTA configuration in a 6/4 GHz transponder. The TWTAs are connected ...

Chapter 4

Figure 4.1 Illustration of a maritime satellite system using a GEO satellite. Ships are eq...

Figure 4.3 Calculation of received power by an antenna with gain

G

r

from a source with...

Figure 4.4 Calculation of received power from a satellite with EIRP

P

t

G

t

watts in...

Figure 4.5a Simplified receiver with single frequency conversion.

Figure 4.5b Frequency plan for single conversion C-band receiver.

Figure 4.6a Double conversion superhet receiver using the same principle as the single conv...

Figure 4.6b Frequency plan for a double conversion Ku-band receiver. The entire 500 MHz ban...

Figure 4.7a Noise model of receiver.

T

in

is the noise temperature of the sky and antenn...

Figure 4.7b Noise model of receiver with a single noise source

T

s

, the system noise t...

Figure 4.7c Noise model of receiver with a single noise source

T

no

, the system noise ...

Figure 4.8 GEO satellite at 30° west longitude with global beam antenna serving the Atlant...

Figure 4.9 GEO satellite at 100°W longitude with elliptical regional beam antenna serving ...

Figure 4.10 Illustration of a direct broadcast satellite television system (

DBS-TV

). The ...

Figure 4.11 Bit error rates for different modulation and coding methods. The DVB-S QPSK wit...

Figure 4.14 Illustration of video distribution system supplying cable TV signals via a GEO ...

Figure 4.15 Illustration of a satellite telephone system using a low earth orbit satellite ...

Chapter 5

Figure 5.1 Illustration of the effect of low pass filtering on a NRZ pulse train. (a) Rand...

Figure 5.2 Transmission and reception of baseband zero ISI pulses. The data stream is the ...

Figure 5.3 Baseband raised cosine transfer function (frequency response) and impulse respo...

Figure 5.4 Waveforms and spectra in a baseband digital transmission system using SRRC filt...

Figure 5.5 Waveforms and spectra in a BPSK radio link with SRRC filtering and NRZ pulse eq...

Figure 5.6 QPSK transmission for a bit stream at 240 Mbps and symbol rate 120 Msps. Only t...

Figure 5.7 (a) Frequency spectrum of an unfiltered QPSK signal with carrier frequency

f

...

Figure 5.8 SRRC waveforms with α = 0.2 and 0.35 generated with six period truncation.

T

...

Figure 5.9a SRRC waveform for continuous 10101010 bit pattern.

Figure 5.9b SRRC waveform for 101011101 bit pattern.

Figure 5.9c SRRC waveform for 10101110 bit pattern.

Figure 5.10 Digital transmitter structure for single data stream with adaptive FEC coding a...

Figure 5.11a Structure of a digital receiver that uses sampling of a second IF signal. The F...

Figure 5.11b Structure of a digital receiver using direct conversion of the RF signal to bas...

Figure 5.12 Illustration of errors in a binary decision circuit. Received pulses have ampli...

Figure 5.13 Theoretical bit error rate (BER) as a function of carrier to noise ratio (CNR) ...

Figure 5.14 Block diagram of conversion of an analog signal to a digital bit stream and rec...

Figure 5.15a Transmit end of a TDM link for

n

channels. Incoming data is buffered and cloc...

Figure 5.15b Receive end of the TDM link for the frames created in Figure 5.15a. The clock i...

Figure 5.16 Generic packet structure. The SYNC block is used to synchronize the bit clock i...

Figure 5.17 Example of error detection using a single parity bit with a seven bit ASCII wor...

Figure 5.18 Selective repeat ARQ. An error is detected at the receiver in block 3. A not ac...

Figure 5.19 Illustration of interleaving. Letters are used in this example to show how the ...

Figure 5.20 Illustration of interpolation to fill in missing data in an analog waveform. Er...

Figure 5.21 Concatenated FEC structure used in the DVB-S and DVB-S2 satellite television st...

Figure 5.22 BER performance with DVB-S and DVB-S2 standard direct broadcast TV transmission...

Chapter 6

Figure 6.1 Phasor diagrams for BPSK, QPSK, and 8-PSK. The transmitted signal has a constan...

Figure 6.2 Constellation diagrams for QPSK and 8-PSK. The dots represent the tips of the p...

Figure 6.3 Constellation diagrams for 16-QAM and 16-APSK. The Gray coding applied in each ...

Figure 6.4 Simplified diagram of a BPSK transmitter and receiver showing modulation and de...

Figure 6.5 Block diagram of a BPSK demodulator. The blocks shown correspond to a hardware ...

Figure 6.6 Block diagram of a QPSK modulator implemented in hardware form.

Figure 6.7 Block diagram of a QPSK demodulator implemented in hardware.

Figure 6.8 Comparison of spectra for unfiltered QPSK, QPSK with

α

 = 0.5 SRRC filtering, ...

Figure 6.9 FDMA and TDMA. The blocks represent signals, which can consist of a single chan...

Figure 6.10 Direct sequence code division multiple access. Individual signals are recognize...

Figure 6.11 Illustration of FDMA. Three transmitting stations send signals at different car...

Figure 6.12 Frequency plan for two C-band transponders using fixed assignment FDMA. The tri...

Figure 6.13 FDMA with 25 channels in a receiver IF with center frequency 70 MHz. The occupi...

Figure 6.14 Intermediate frequency section of an FDMA receiver for 25 data channels. The fi...

Figure 6.15 12.5 GHz FDMA transmitter for three T1 channels. The transmitter sends its sign...

Figure 6.16 Illustration of intermodulation with two C-band carriers in a non-linear transp...

Figure 6.17 Illustration of TWTA HPA transponder non-linear characteristic. The saturated o...

Figure 6.18 Illustration of optimization of overall CNR in a typical satellite transponder....

Figure 6.19 Illustration of third order intermodulation in a low power RF amplifier. The sa...

Figure 6.20 Concept of TDMA. Earth stations in a TDMA network transmit bursts at specific t...

Figure 6.21 A TDMA frame with

N

earth stations in the network. The reference burst is use...

Figure 6.22 Typical structure of a transmitted TDMA burst in a network of large earth stati...

Figure 6.23 A STAR network. Outbound traffic is sent from the gateway to VSAT stations via ...

Figure 6.24 A MESH network. All stations can connect to one another, or to the gateway.

Figure 6.25 Schematic diagram of a baseband processing transponder with a multiple beam ant...

Figure 6.26 FDMA and MF-TDMA loading of a 20 MHz transponder in a VSAT star network. There ...

Figure 6.27 Schematic diagram of a gateway station for FDMA VSAT signals using hardware in ...

Figure 6.28 Illustration of Aloha and slotted Aloha. Letters indicate the transmitting stat...

Figure 6.29 Packet structure used in the AX.25 amateur protocol. The unnumbered frame is us...

Figure 6.30 Simplified diagram of the C/A code generator used on GPS satellites. The output...

Figure 6.31 Single channel correlator for C/A code acquisition. The BPF has a bandwidth of ...

Figure 6.32 Operation of the correlator in a GPS C/A code receiver. The IF signal

V

1 has ...

Figure 6.33 The locally generated C/A code does not match the received GPS C/A code signal,...

Chapter 7

Figure 7.1 Schematic of the bit error rate (BER) statistic for a typical communications li...

Figure 7.2 Schematic of the loss statistics encountered by a signal on transmission throug...

Figure 7.4 Illustration of the various propagation loss mechanisms on a typical earth-spac...

Figure 7.4 Approximate range of annual time percentages that various atmospheric impairmen...

Figure 7.5 (

a

) Stratiform rain situation. In this case, a widespread system of stratifor...

Figure 7.6 (

a

) Stratiform rain attenuation calculation procedure. In the case of stratif...

Figure 7.7 Example of an RHI scan through a rain storm. Radar reflectivity contours in a r...

Figure 7.8 Orthogonally polarized waveguide horn antennas. The polarization of an electrom...

Figure 7.9 Fields excited by a dual-polarized antenna. The field radiated by the

V

horn ...

Figure 7.10 Illustration of signal depolarization in the transmission path. The transmitted...

Figure 7.11 Total zenith attenuation due to atmospheric gases calculated from 3 to 350 GHz....

Figure 7.12 Schematic of stratified and turbulent conditions in the

boundary layer

of the...

Figure 7.13 Scintillations observed under a variety of weather conditions on a 30 GHz downl...

Figure 7.14 Typical rainfall rate cumulative probability distributions or

exceedance

curv...

Figure 7.16 Rainfall rate exceedance contours for the Americas. This was the first set of t...

Figure 7.17 Rain intensity (mm/h) exceeded for 0.01% of the average year. This map provides...

Figure 7.18 Cumulative statistics of rainfall rate and path attenuation illustrating equipr...

Figure 7.19 Geometry of a satellite path through rain. The height of the melting layer, sho...

Figure 7.20 Example of different path length geometries. In both cases, a similar rainstorm...

Figure 7.22 Schematic of the shape of an individual raindrop from formation to maturity.

Figure 7.23 A simplified explanation of rain depolarization based on a drop with an ellipti...

Figure 7.24 Illustration of canting angle. The resultant of the prevailing wind force and t...

Figure 7.25 Schematic of tilt angle. In (

a

) above,

S

, is the subsatellite point of a GE...

Figure 7.26 Schematic of the additional radiated sky temperature due to absorption in rain....

Figure 7.27 Instantaneous 30 : 20 GHz attenuation scaling ratio with 20 GHz attenuation as ...

Figure 7.28 Illustration of diversity gain and diversity improvement (diversity advantage)....

Chapter 8

Figure 8.1 Classification of small satellites (smallsats). Examples of some small satellit...

Figure 8.2 Division of the electromagnetic spectrum. In the above figure, abstracted from ...

Figure 8.3 The three ITU regions.

Figure 8.6 Observation arc of the satellite seen from position

G

as it moves from

E

2

...

Figure 8.7 Calculation of the observation arc distance from

E

2

to

E

1

.

Figure 8.8 Schematic of a Hall effect thruster. The lightweight fuel, either in solid or l...

Figure 8.9 Schematic of a two front fed parabolic antennas in receive mode. The left hand ...

Figure 8.10 Schematic of a smallsat with a 1 m diameter parabolic antenna attached. Note th...

Figure 8.11 Illustration of an inflatable antenna. Not depicted are the supporting feed str...

Figure 8.12 Illustration of another inflatable antenna concept. It looks like a rubber ding...

Figure 8.13 Schematic of the penetration depth of different downlink observation frequencie...

Figure 8.14 (a) Star network. All links go through the gateway earth station. Individual VS...

Figure 8.15 Schematic of a VSAT wireless local loop (WLL) concept. The local loop can provi...

Figure 8.16 Schematic of the OSI/ISO and TCP/IP protocol stacks. The OSI model was develope...

Figure 8.17 Illustration of a communications link with a 10 ms one-way delay and a 60 ms wi...

Figure 8.18 Illustration of a communications link with a 260 ms one-way delay and a 60 ms w...

Figure 8.19 Protocol architecture of a Star VSAT network. VSAT networks are normally mainta...

Figure 8.21 Schematic of 64 kbps equivalent voice channel accessing a satellite using FDMA....

Figure 8.22 Schematic of the TDM downlink outbound channel from the control station, via th...

Figure 8.23 Illustration of a VSAT network frequency assignment in which the inbound and ou...

Figure 8.24 Example of a multifrequency TDMA (MF-TDMA) scheme. In this particular case, fiv...

Figure 8.25 Illustration of how a VSAT can cause interference to other satellite systems. I...

Figure 8.26 Illustration of the different layers of protocols used in VSAT networks (after ...

Figure 8.27 Generic sequence for the start of a burst from a VSAT inbound signal. When the ...

Figure 8.28 Schematic of the encoding and decoding process when an

inner

and

outer

code...

Figure 8.29 BER vs. E

b

/N

o

performance of coherent QPSK for various types of codes. A 1....

Figure 8.30 Illustration of the interference geometry between a VSAT and a satellite of ano...

Figure 8.31 Schematic of the typical location of VSAT component parts. The VSAT outdoor uni...

Figure 8.32 Schematic of the typical configuration of a VSAT earth station. The low noise c...

Chapter 9

Figure 9.1 (a) Coverage of an equatorial orbit LEO satellite. The LEO satellite is in an e...

Figure 9.2 (a) Store-and-forward concept. In this LEO application, the satellite stores in...

Figure 9.3 Schematic of an elliptical orbit illustrating eccentricity. The satellite orbit...

Figure 9.4 Schematic of a Molniya orbit. In this example, the trajectory is configured to ...

Figure 9.5 Schematic of an operational Molniya system. Satellite 1 in Molniya orbit 1 is p...

Figure 9.6 View from above the Molniya orbit apogee showing the ground track (Watson priva...

Figure 9.7 Representation of the magnetic field lines that flow between the north and sout...

Figure 9.8 The general variation of the sunspot number over solar cycle 22. The smoothed s...

Figure 9.9 Pictorial representation of the two Van Allen radiation belts. The above schema...

Figure 9.10 Examples of two sun synchronous orbits. In the illustration above, the earth is...

Figure 9.11 Illustration of the alignment changes of the orbital plane of a satellite due t...

Figure 9.12 Geometry for calculating coverage area. The satellite, earth station, and the c...

Figure 9.13 Illustration of the decrease in the path through rain as the elevation angle to...

Figure 9.14 Illustration of coverage area under a satellite. In this example, an NGSO satel...

Figure 9.15 Illustration of a three-cell re-use pattern. The instantaneous coverage of the ...

Figure 9.16 (a) User spot beams developed by an Iridium satellite. The satellite covers abo...

Figure 9.17 Illustration of scan angle control mechanisms for phased array antennas. (a) Pa...

Figure 9.18 (a) Point-to-point line-of-sight terrestrial communications link. The transmit ...

Figure 9.19 Schematic of the total scan angles for LEO, MEO, and GEO satellites. The furthe...

Figure 9.20 Illustration of path loss and scan angle loss evaluation for a phased array. Th...

Figure 9.21 Illustration of the scan angle of an individual beam within an instantaneous co...

Figure 9.22 A sketch of an Iridium satellite. One of the three phased array antennas is sho...

Figure 9.23 Relative transmission loss and minimum grazing angle vs. satellite altitude for...

Figure 9.24 Relative transmission loss and minimum grazing angle vs. satellite altitude for...

Figure 9.25 One-way propagation delay for the three orbits shown: LEO, MEO, and GEO. The on...

Figure 9.26 Schematic of the ISL seam in the Iridium constellation. The Iridium satellites ...

Figure 9.27 Polar view of the Iridium next constellation. (Source: From Figure C, Iridium 2...

Figure 9.28 Schematic of a 64 kbps equivalent voice channel accessing a satellite using FDM...

Figure 9.29 Approximate economic break points in the implementation choices for serving new...

Figure 9.30 Percentage of the world's population living in the given latitude ranges. The d...

Figure 9.31 Schematic of end-to-end connection of satellites that have no onboard processin...

Figure 9.32 Concept of a stationary cell. Unlike the coverage of the NGSO satellite shown i...

Figure 9.33 Coverage results from system design example in Section 9.6. The coverage of one...

Chapter 10

Figure 10.1 Virginia Tech earth station. The two Cassegrain antennas in the left of the pho...

Figure 10.2 Growth in subscribers to US DBS-TV services. Growth flattened out by 2015 as in...

Figure 10.3 Illustration of a Ku-band DBS-TV system. The uplink earth station typically has...

Figure 10.4 Simplified diagram of the signal processing in a DTH-TV link. Video (V), audio ...

Figure 10.5 A large GEO direct broadcast television satellite under test prior to launch. T...

Figure 10.6 Examples of DBS-TV receiving antennas at the author's home (TP) in Blacksburg, ...

Figure 10.9 Simplified diagram of a single channel satellite receiver for Ku-band DBS-TV sy...

Figure 10.10 Non-linear characteristic of typical TWTA and linearization with a compensating...

Figure 10.11 Typical bit error rate for DVB-S and DVB-S2 links with 1.8 dB implementation ma...

Figure 10.12 Packet and frame structure of DVB-S2 transmissions. (a) The basic packet is an ...

Figure 10.13 Frame structure and header for short frame DVB-S2 transmissions using MPEG-2 co...

Figure 10.14 Performance for DVB-S2 QPSK and 8-PSK modulation-coding combinations with 1.0 d...

Figure 10.15 Antennas at the studios of the WDBJ television station in Roanoke, Virginia. Th...

Figure 10.16 Satellite truck used by the WDBJ television station in Roanoke, Virginia, for o...

Figure 10.17 Typical conus beam of a DBS-TV satellite serving the United States in Ku-band. ...

Figure 10.18 Example of spot beams generated by a Ku-band DBS-TV satellite serving the conti...

Figure 10.19 Simplified block diagram of a DTH TV transmitting station. The upper blocks in ...

Chapter 11

Figure 11.1 Illustration of a GSO internet access system. The user terminals are equipped w...

Figure 11.2 (a) Illustration of ViaSat 1. For a color version of this figure please see col...

Figure 11.3 Spectral efficiency of DVB-S2 links for several combinations of modulation and ...

Figure 11.4 Adaptive coding and modulation applied to counter rain attenuation in the downl...

Figure 11.5 Adaptive coding and modulation applied to counter rain attenuation in the uplin...

Figure 11.6 Examples of scintillation and rain attenuation on a 30 GHz slant path from the ...

Figure 11.7 Illustration of a NGSO satellite internet access system. The gateway station ha...

Figure 11.8 Illustration of NGSO link cone of visibility. The minimum permitted elevation a...

Figure 11.9 Illustration of a gateway station with three NGSO satellites visible to three e...

Figure 11.10 Illustration of elevation over azimuth and X-Y antenna mounts. In Figure 11.10a...

Figure 11.11 Frame structure and header for short frame DVB-S2 transmissions using MPEG-2 co...

Figure 11.12 Illustration of a community antenna system for internet access that can provide...

Figure 11.13 (a) Example of transponders for a gateway to user link in a GSO internet access...

Figure 11.14 (a) Onboard processing transponders for NGSO internet access system gateway to ...

Figure 11.15 Comparison of GSO and LEO spot beam dimensions over southwest Virginia. (a) Via...

Chapter 12

Figure 12.2 Position location by trilateration. The aircraft must receive signals from thre...

Figure 12.3 Position location by the measurement of the distance from three known points. T...

Figure 12.4 Generation of C/A and P-code signals in early Block II GPS satellites. The C/A ...

Figure 12.5 C/A code generator. Identical code generators are used on GPS satellites and in...

Figure 12.6 Simplified diagram of a single frequency C/A code GPS receiver. Signal frequenc...

Figure 12.7 Single channel correlator for C/A code acquisition. The BPF has a bandwidth of ...

Figure 12.8 Illustration of the correlation process when the locally generated C/A code V2 ...

Figure 12.9 Illustration of the correlation process when the locally generated C/A code V2 ...

Figure 12.10 Simplified phase locked loop. LPF, low pass filter.

Figure 12.11 Non-coherent delay lock loop and navigation message recovery. The IF input sign...

Figure 12.12 Delay lock loop correlator outputs corresponding to the punctual, early, and la...

Figure 12.13 Costas loop used to demodulate the 50 Hz BPSK navigation message. LPF, low pass...

Figure 12.14 Overview of the ADS-B system for air traffic control. The system is based on GP...

Chapter appendix a

Figure A.1 Illustration of a voltage divider circuit.

V

S

is a voltage source

, R

S

...

Chapter appendix b

Figure B.1 Radiation pattern for an antenna with a gain of 33 dB. (a) Pattern plotted on C...

Figure B.2 Small antennas and their radiation patterns. (a) A vertical half wave dipole in...

Figure B.3 (a) A Yagi antenna with seven elements. (b) A three turn helix antenna. (c) A r...

Figure B.4 (a) Symmetrical parabolic reflector antenna. The feed and LNB block part of the...

Figure B.5 Early design of DBS-TV receiving antenna with a circular aperture and a single ...

Figure B.6 (a) Symmetrical Cassegrain antenna. The main reflector shape is a paraboloid an...

Figure B.7 A linear radiating aperture. The field at point P is the summation of contribut...

Figure B.8 Illustration of an offset Cassegrain antenna for a large GEO satellite with a n...

Figure B.9 Four element phased array. Each element radiates a spherical wavefront that sum...

Chapter appendix d

Figure D.1 (a) Sampling of signal

v

(

t

) by a square wave

s

(

t

). (b) Waveform of sign...

Figure D.2 Spectra of signals in Figure D.1. The narrow line in the spectrum represents a ...

Figure D.3 Spectra of the sine wave signal

v

(

t

)and the sampled signal v

s

(

t

). The s...

Figure D.4 Recovery of signal

v

(

t

) from the sampled signal with a low pass filter. The...

Figure D.5 A generic voice signal, represented by a triangle indicating

f

min

and

f

m

...

Figure D.6 Aliasing caused by a low pass filter with slow roll off, or by a sampling frequ...

Figure D.7 Simplified diagram of a digital transmission system for analog signals. The low...

Figure D.8 Illustration of the quantization process for a 3 bit ADC, and typical quantizat...

Figure D.9 Gain characteristic of a compressor and an expander in a typical companded link...

Figure D.10 Illustration of the reduction in quantization noise for small signals when non-...

Guide

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Preface

The first edition of Satellite Communications was published in 1986, with the second edition following in 2003. There have been many changes in the 33 years since the first edition appeared, with a complete transition from analog to digital communication systems. The launch of satellites, once the province of government agencies, is now a thriving commercial business. By the time this third edition reaches the market, a number of private citizens will have entered the lower reaches of space as tourists. Analog transmission techniques have been replaced by digital modulation and digital signal processing. Spinner satellites have virtually disappeared, replaced by a much wider range of satellites from cubesats with mass less than 1 kg to large GEO satellites with mass exceeding 6000 kg. While distribution of television programming remains the largest sector of commercial satellite communications, earning approximately half of the worldwide revenue from satellite communication systems, low earth orbit constellations of satellites for internet access are set to challenge that dominance.

Satellite communication systems have made a very significant contribution to world economics and society. An international telephone call that cost US$1 per minute in 1960 could be dialed for less than US$0.02 per minute in 2000. Taking account of inflation, the cost of communications has been reduced by a factor of more than 1000, a claim that very few other services can make. Access to the internet will become available to 3 billion people in countries that lack a terrestrial communication system as new constellations of LEO satellites are launched. Global satellite navigation systems help motorists to find their way to their destination and make travel by ships and aircraft safer. Two way television links via satellite enable news from anywhere in the world to be available 24 hours a day. Fiber optic systems have contributed significantly to these achievements, but satellite systems provide service wherever there is a need to broadcast to many locations. These contributions to quality of life have been made possible by the efforts of thousands of telecommunications engineers who design, produce, and maintain the systems that allow us to communicate with almost anyone, anywhere. Rarely do these engineers receive credit from the general public for these achievements.

In writing the third edition of Satellite Communications we have followed the intent of the first two editions; to provide a text that can be used in undergraduate and beginning graduate courses to introduce students to the subject, and also by engineers in industry and government to gain a sound understanding of how a satellite communication system works. The subject of satellite communications is extensive and we make no claims to have provided comprehensive coverage of the subject. An internet search for satellite communications yielded more than 250 000 entries in 2018, and there are textbooks available that expand on the topics of each of our individual chapters. In the third edition, chapters 1–3 cover topics that are specific to satellites, including orbits, launchers, and spacecraft. Chapters 4–7 cover the principles of digital communication systems, radio frequency communications, digital modulation and multiple access techniques, and propagation in the earth's atmosphere, topics that are common to all radio communication systems. The chapter in the second edition on VSATs has been significantly expanded with the addition of low throughput satellite systems, otherwise known as SmallSats or cubeSats. These satellites range from experimental payloads assembled by undergraduate students to SmallSats that accompany advanced missions, such as the two that accompanied the Insight lander, which landed on Mars in late 2018. Also significantly expanded is the chapter dealing with rockets and launchers. Chapters 8–12 cover applications that include non-geostationary satellite systems, low throughput systems, direct broadcast satellite television, internet access by satellite, and global navigation satellite systems. The chapter on internet access by satellite is new to the third edition, and each of the chapters has been extensively revised to include the many changes in the field since 2003. Two new appendices have been added that cover digital transmission of analog signals, and antennas. These are topics that, in our experience, many students do not understand well yet are vital to most communication systems.

One of the most far reaching changes in communication systems technology has been the introduction of digital signal processing. High density integrated circuits are available that implement almost all of the functions required in transmitters and receivers in one or two devices. This is also true of spacecraft components such as three-axis control, which can now consist of a miniaturized digital controller rather than a group of two or three heavy momentum wheels. Liquid bi-propellant thrusters have been supplemented, and in some cases completely replaced by electric thrusters using xenon-ion propulsion systems.

Our text makes extensive use of block diagrams to explain how successive operations are performed on signals to obtain a specific result, for example, modulation of a digital signal onto an RF carrier or selection of a specific signal from a wide band multiplex of many signals. The blocks correspond to identifiable parts of a traditional analog system working in the frequency domain that could previously have been found in a transmitter or receiver, but are now part of a digital processor working in the time domain. Block diagrams are essential in understanding how communication systems are built up from successive operations on signals, but we recognize that in many cases the blocks are now implemented as digital operations.

The internet, and powerful search engines, have made it possible to find information about almost any subject in a few minutes. The reference section of the chapters of the third edition contain fewer references to papers and text books than previous editions and more references to internet sites. Although the specific sites may disappear with time, a search for the relevant topic will usually provide many alternative references. The internet has forced another change in the third edition. Our experience in teaching university courses has shown that the solutions to any problems issued to students for homework and exams appear very quickly at internet sites, and this is often the first place that students go to find answers, regardless of any rules that prohibit such action. As a result, we will not provide a solutions manual for the third edition. We have included exercises at the end of each chapter that instructors can use as the basis for homework problems, but our advice is to change the parameters of the questions each time one of the exercises is used. This forces students to work through the problem even if a similar internet solution is found, rather than just copying the solution. Changing the first sentence of the question also makes it harder for students to find an internet solution.

The authors would like to thank their colleagues and students who, over the years, have made many valuable suggestions to improve this text. Their advice has been heeded and the third edition is the better for it. In particular, we want to acknowledge the contributions of Dr. Charles Bostian, Alumni Distinguished Professor Emeritus of Electrical and Computer Engineering, co-author of the first and second editions, who first suggested that we should write a book on satellite communications. Dr. Bostian's writing can be found in parts of several chapters of the third edition that cover the basic theory of satellite communications. Dr. Bostian founded the Satellite Communications Group at Virginia Tech and led research that has contributed significantly to the success of many satellite communications systems.

About the Authors

Timothy Pratt is an Emeritus Professor of the Bradley Department of Electrical and Computer Engineering at Virginia Tech, having retired in 2013. He received his B.Sc. and Ph.D. degrees in electrical engineering from the University of Birmingham, UK, and taught courses on satellite communications in the UK and the United States for 40 years. Dr. Pratt is a lifetime senior member of the IEEE. He lives on a farm outside Blacksburg with his wife and several dogs and cats, and many white tail deer.

Jeremy Allnutt is an Emeritus Professor of the Electrical and Computer Engineering Department of George Mason University, having retired in 2014. His primary interest is radiowave propagation effects on satellite links, which he pursued at research establishments in England and Canada, before working at INTELSAT in the US from 1979 to 1994. Prior to joining George Mason University in 2000, he was a professor at the University of York, UK, and at Virginia Tech. Dr. Allnutt obtained his B.Sc. and Ph.D. in Electrical Engineering from Salford University, UK, and is a Fellow of IET and a Fellow of the IEEE. He lives in Blacksburg with his wife, two dogs, two cats, and several birds, rabbits, and deer that consider his backyard to be their home as well.

1Introduction

Two developments in the nineteenth and twentieth century changed the way people lived: the automobile and telecommunications. Prior to the widespread availability of personal automobiles, individuals had to travel on foot, by bicycle, or on horseback. Trains provided faster travel between cities, but most people's lives were centered on their home town and immediate surroundings. A journey of 100 miles was a major expedition for most people, and the easy mobility that we all take for granted in the twenty-first century was unknown. Before the telegraph and telephone came into widespread use, all communication was face to face, or in writing. If you wanted to talk to someone, you had to travel to meet with that person, and travel was slow and arduous. If you wanted to send information, it had to be written down and the papers hand-carried to their destination.

Telecommunication systems have now made it possible to communicate with virtually anyone at any time. Early telegraph and telephone systems used copper wire to carry signals over the earth's surface and across oceans, and high frequency (HF) radio made possible intercontinental telephone links.

The development and installation of optical fibers and optical transmission techniques has greatly increased the capacity of terrestrial and oceanic links. Artificial earth satellites have been used in communications systems for more than 50 years and have become an essential part of the world's telecommunications infrastructure. Satellites allow people to receive hundreds of television channels in their homes, either by receiving direct broadcast satellite television signals, or via cable TV from a satellite distribution center. Virtually all cable TV systems collect their signals from satellites that distribute television programming nationwide. Access to the internet via satellite from areas that are not served by cable is also available, providing many people in rural areas with much faster service than can be achieved over telephone lines.

1.1 Background

The origins of satellite communications can be traced to an article written by Arthur C. Clarke in the British radio magazine Wireless World in 1945 (Clarke 1945). At the time, Clarke was serving in the British Royal Air Force, working on precision approach radar systems that could guide World War II aircraft to a safe landing when the airport was fogged in. He was interested in long distance radio communication and was among the first to propose a practical way to communicate using satellites. He later became famous as the author of 2001: A Space Odyssey, and other science fiction books (Clarke 1968). In 1945, HF radio was the only available method for radio communication over transcontinental distances, and it was not at all reliable. Sun spots and ionospheric disturbances could disrupt HF radio links for days at a time. Telegraph cables had been laid across the oceans as early as the mid-1800s, but cables capable of carrying voice signals across the Atlantic did not begin service until 1953. Clarke suggested that a radio relay satellite in an equatorial orbit with a period of one sidereal day would remain stationary with respect to the earth's surface and make possible long distance radio links. (A sidereal day is the time it takes for the earth to make one complete revolution on its axis. It is 3 minutes 55.91 seconds shorter than a clock day of 24 hours, accounting for the progress of the earth around the sun in 365 days, which adds one additional revolution.)

Clarke's Wireless World paper is available on the internet and makes fascinating reading (Clarke 1945). Solar arrays had not been developed in 1945, so Clarke proposed a solar collector driving a steam engine to generate electrical power; a manned space station was needed to run the complicated systems. In most other respects, Clarke accurately predicted the development of geostationary earth orbit (GEO) satellites for direct broadcast television and data communications using transmitter powers much lower than the kilowatt levels of terrestrial broadcasting, and small parabolic mirrors (dishes) for receiving terminals.

At the time Clarke wrote his paper there were no satellites in orbit nor rockets powerful enough to launch them. But his ideas for what we now know as a geostationary satellite system were not science fiction, as the launch of the Russian satellite Sputnik in 1957 and subsequent GEO satellites was to prove. In 1965 the first geostationary communications satellite, Early Bird, began to provide telephone service across the Atlantic Ocean, fulfilling Clarke's vision of 20 years earlier. Intelsat launched a series of satellites between 1967 and 1969 that provided coverage of the Atlantic, Pacific, and Indian ocean regions, making worldwide coverage by GEO satellite possible, just in time for the Apollo 11 mission that first sent humans to the moon.