|
|
马上注册，结交更多好友，享用更多功能，让你轻松玩转社区。
您需要 登录 才可以下载或查看，没有账号？注册
x
<Preface>
Satellite communication is one of the most impressive spin-offs from space
programs, and has made a major contribution to the pattern of international
communications. The engineering aspect of satellite communications
combines such diverse topics as antennas, radio wave propagation, signal
processing, data communication, modulation, detection, coding, filtering,
orbital mechanics, and electronics. Each is a major field of study and each
has its own extensive literature. Satellite Communication Engineering emphasizes
the relevant material from these areas that is important to the book’s
subject matter and derives equations that the reader can follow and understand.
The aim of this book is to present in a simple and concise manner the
fundamental principles common to the majority of information communications
systems. Mastering the basic principles permits moving on to concrete
realizations without great difficulty. Throughout, concepts are developed
mostly on an intuitive, physical basis, with further insight provided by
Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.
means of a combination of applications and performance curves. Problem sets
are provided for those seeking additional training. Starred sections containing
basic mathematical development may be skipped with no loss of continuity by
those seeking only a qualitative understanding. The book is intended for
electrical, electronics, and communication engineering students, as well as
practicing engineers wishing to familiarize themselves with the broad field of
information transmission, particularly satellite communications.
The first of the book’s eight chapters covers the basic principles of
satellite communications, including message security (cryptology).
Chapter 2 discusses the technical fundamentals for satellite communications
services, which do not change as rapidly as technology and provides the
reader with the tools necessary for calculation of basic orbit characteristics
such as period, dwell time, and coverage area; antenna system specifications
such as type, size, beam width, and aperture-frequency product; and power
system design. The system building blocks comprising satellite transponder
and system design procedure are also described. While acknowledging that
systems engineering is a discipline on its own, it is my belief that the reader
will gain a broad understanding of system engineering design procedure,
accumulated from my experience in large, complex turnkey projects.
Earth station, which forms the vital part of the overall satellite system, is
the central theme of Chapter 3. The basic intent of data transmission is to
provide quality transfer of information from the source to the receiver with
minimum error due to noise in the transmission channel. To ensure quality
information requires smart signal processing technique (modulation) and
efficient use of system bandwidth (coding, discussed extensively in Chapter
6). The most popular forms of modulation employed in digital communications,
such as BPSK, QPSK, OQPSK, and 8-PSK, are discussed together with
their performance criteria (BER). An overview of information theory is given
to enhance the reader’s understanding of how maximum data can be transmitted
reliably over the communication medium. Chapter 3 concludes by
describing a method for calculating system noise temperature and the items
that facilitate primary terrestrial links to and from the Earth stations.
Chapter 4 discusses the process of designing and calculating the carrierto-
noise ratio as a measure of the system performance standard. The quality of
signals received by the satellite transponder and that retransmitted and
received by the receiving earth station is important if successful information
transfer via the satellite is to be achieved. Within constraints of transmitter
power and information channel bandwidth, a communication system must be
designed to meet certain minimum performance standards. The most important
performance standard is ratio of the energy bit per noise density in the
Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.
information channel, which carries the signals in a format in which they are
delivered to the end users.
To broadcast video, data, and=or audio signals over a wide area to many
users, a single transmission to the satellite is repeated and received by multiple
receivers. While this might be a common application of satellites, there are
others which may attempt to exploit the unique capacity of a satellite medium
to create an instant network and connectivity between any points within its
view. To exploit this geometric advantage, it is necessary to create a system of
multiple accesses in which many transmitters can use the same satellite
transponder simultaneously. Chapter 5 discusses the sharing techniques
called multiple access. Sharing can be in many formats, such as sharing the
transponder bandwidth in separate frequency slots (FDMA), sharing the
transponder availability in time slots (TDMA), or allowing coded signals to
overlap in time and frequency (CDMA). The relative performance of these
sharing techniques is discussed.
Chapter 6 explores the use of error-correcting codes in a noisy communication
environment, and how transmission error can be detected and
correction effected using the forward error correction (FEC) methods,
namely, the linear block and convolutional coding techniques. Examples are
sparingly used as illustrative tools to explain the FEC techniques.
The regulation that covers satellite networks occurs on three levels:
international, regional, and national. Chapter 7 discusses the interaction
among these three regulatory levels.
Customer’s demands for personalized services and mobility, as well as
provision of standardized system solutions, have caused the proliferation of
telecommunications systems. Chapter 8 examines basic mobile-satellitesystem
services and their interaction with land-based backbone networks—in
particular the integrated service digital network (ISDN). Since the services
covered by ISDN should also, in principle, be provided by digital satellite
network, it is necessary to discuss in some detail the basic architecture of
ISDN as well as its principal functional groups in terms of reference
configurations, applications, and protocols. Chapter 8 concludes by briefly
looking at cellular mobile system, including cell assignment and internetworking
principles, as well as technological obstacles to providing efficient Internet
access over satellite links.
The inspiration for writing Satellite Communication Engineering comes
partly from my students who have wanted me to share the wealth of my
experience acquired over the years and to ease their burden in understanding
the fundamental principles of satellite communications. A very special thanks
go to my darling wife, Dr. Marjorie Helen Kolawole, who actively reminds me
Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.
about my promise to my students, and more importantly to transfer knowledge
to a wider audience. I am eternally grateful for their vision and support.
I also thank Professor Patrick Leung of Victoria University, Melbourne,
Australia, for his review of the manuscript and his constructive criticisms, and
acknowledge the anonymous reviewers for their helpful comments.
Finally, I want to thank my family for sparing me the time, which I
would have otherwise spent with them, and their unconditional love that keeps
me going. |
|
/2 
eetop公众号
创芯大讲堂
创芯人才网
发表于 2008-10-30 01:21:59
