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小 发表于 07-2-28 17:23 只看该作者
Satellite Communication Engineering
Satellite Communication Engineering |  | 收藏 | | | 作者 | Michael O. Kolawole; | | ＩＳＢＮ | 082470777X | | 出版日期/版本 | 15 June, 2002 | | 格式 | ＰＤＦ Adobe Acrobat |
主题内容 | | Satellite communication is one of the most impressive spin-offs from spaceprograms, 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 emphasizesthe 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 bymeans of a combination of applications and performance curves. Problem sets are provided for those seeking additional training. Starred sections containing basic mathematical evelopment 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 Chapter6). 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 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 manyusers, 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 itsview. 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 interactionamong 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.
[ 本帖最后由 shenxw602 于 07-2-28 17:25 编辑 ] |
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