数字信号处理--基于计算机的方法（英文影印版·第3版）

　　mitra教授的《数字信号处理——基于计算机的方法》(第2版)(影印版)于2001年由清华大学出版社推出以来，得到了广大院校师生的一致好评，并对国内高校双语教学的展开起到了积极的推动作用。.
　　 在推出的第5版缩编影印版，由国内知名教授根据教学经验和教学要求提出缩编方案，使之既满足国内学生阅读国外经典教材的需求，又最大程度地维护原著的特色与风格。
　　 本书非常适合电类专业本科生用作教材，也可作为研究生的参考用书和工程技术人员的自学用书。..
　　 mitra教授是国际上著名的信号处理专家。他在加利福尼亚大学伯克利分校获得硕士和博士学位，先后在康奈尔大学、at&t贝尔实验室、加利福尼亚大学戴维斯分校、圣·巴巴拉分校任教和工作。他曾任圣·巴巴拉分校电气与计算机工程系主任，ieee电路与系统学会的主席，ieee、aaas和spie学会的fellow，多个国际著名杂志的编委，并获得过多项企业和学术界的奖励。他发表了学术论文600多篇，出版了12本著作，拥有5项专利。他还是美国工程院院士、芬兰科学院院士、挪威技术科学院院士、墨西哥工程院外籍院士等。...

preface
1 signals and signal processing.
1.1 characterization and classification of signals
1.2 typical signal processing operations
1.3 examples of typical signals
1.4 typical signal processing applications
1.5 why digital signal processing?
2 discrete-time signals and systems
2.1 discrete-time signals
2.2 typical sequences and sequence representation
2.3 the sampling process
2.4 discrete-time systems
2.5 time-domain characterization of lti discrete-time systems
2.6 simple interconnection schemes
2.7 finite-dimensional lti discrete-time systems
2.8 classification of lti discrete-time systems
2.9 correlation of signals
2.10 random signals
2.11 summary
2.12 problems

　　The field of digital signal processing (DSP) has seen explosive growth during the past four decades, as phenomenal advances both in research and application have been made. Fueling this growth have been the advances in digital, computer technology and software development. Almost every electrical and computer engineering department in this country and abroad now offers one or more courses in digital signal processing, with the first course usually being offered at the senior level. This book is intended for a two-semester course on digital signal processing for seniors or first-year graduate students. It is also written at a level suitable for self-study by the practicing engineer or scientist. .
　　Even though the second edition of this book was published barely three years ago, based on the feedback received from professors who adopted this book for their courses and many readers, it becameevident that a new edition was needed to incorporate the suggested changes to the contents. Three types of changes were made to the manuscript: inclusion of a number of new topics, elimination of some topics, and a major reorganization of the materials. We believe the materials in each chapter are now organized more logically. In addition more worked-out examples have been included to explain new and difficult concepts.
　　One major change occurring in the third edition is the splitting of the chapter on transform-domain representations of discrete-time signals and systems into three chapters: one chapter on the discrete-time Fourier transform (DTFT) representation, a second one on the discrete Fourier transform (DFT) representation, and the third one on the z-transform representation. The chapter on discrete-time Fourier transform representation also includes a brief review of the continuous-time Fourier transform (CTFT) representation of continuous-time signals and systems to point out the basic similarities and differences between the two transforms. The concept of the frequency response of a linear, time-invariant discrete-time system and its properties are discussed in this chapter. The chapter containing a discussion of the DFT includes a review of two other finite-length discrete transforms, namely, the discrete cosine transform DCT) and the Haar transform. These two latter transforms are often used in signal compression. The concept of the transfer function of a linear, time-invariant discrete-time system is reviewed in the chapter on the z-transform representation.
　　The second major change implemented in this edition is to cover the design of infinite impulse response (IIR) and finite impulse response (FIR) digital filters in two separate chapters. The third major change involves the splitting of the chapter on multirate digital signal processing into two chapters. The first chapter covers a discussion on fundamental concepts of multirate digital signal processing, while the second chapter includes a discussion on filter banks and discrete wavelet transform. Finally, relevant materials on discrete-time random signals are included as an appendix.
　　The new topics included in the third edition are continuous-time Fourier transform (Section 3.1), unwrapped phase function (Section 3.7), phase and group delays (Section 3.9), Fourier-domain filtering (Section 5.8), discrete cosine transform (Section 5.11), Haar transform (Section 5.12), energy compaction properties of the finite-length discrete transforms (Section 5.13), transfer function classification based on magnitude and phase characteristics (Sections 7.1 and 7.2), minimum-phase FIR filter design (Section 10.4), spectral factorization (Section 10.4), computationally efficient FIR filter design (Section 10.6), fast discrete Fourier transform computation using index mapping (Section 11.4), sliding discrete Fourier transform (Section 11.6), discrete Fourier transform computation over a narrow frequency band (Section 11.7), spline interpolation (Section 13.5), discrete-wavelet transform (Section 14.6), digital music synthesis (Section 15.7), and wavelet-based signal compression (Section 15.9).
　　A key feature of this book is the extensive use of MATLAB~ -basedI examples that illustrate the program's powerful capability to solve signal processing problems. The book uses a three-stage pedagogical structure designed to take full advantage of MATLAB and to avoid the pitfalls of a "cookbook" approach to problem solving. First, each chapter begins by developing the essential theory and algorithms. Second, the material is illustrated with examples solved by hand calculation. And third, solutions are derived using MATLAB. From the beginning, MATLAB codes are provided with enough details to permit the students to repeat the examples on their computers. In addition to conventional theoretical problems requiring analytical solutions, each chapter also includes a large number of problems requiring solution via MATLAB. This book requires a minimal knowledge of MATLAB. We believe students learn the intricacies of problem solving with MATLAB faster by using tested, complete programs and then writing simple programs to solve specific problems that are included at the ends of Chapters 2 to 15.
　　Because computer verification enhances the understanding of the underlying theories, as in the first two editions, a large library of worked-out MATLAB programs are included in the third edition. The original MATLAB programs of the second edition have been updated to run on the newer versions of MATLAB and the Signal Processing Toolbox. In addition, new MATLAB programs and code fragments have been added in this edition. All MATLAB programs are included in the CD accompanying this text. The reader can run these programs to verify the results included in the book. All MATLAB programs and code fragments in the text have been tested under version 7 (Release 14) of MATLAB and version 6.2 of the Signal Processing Toolbox. Some of the programs listed in this book are not necessarily the fastest with regard to their execution speeds, nor are they the shortest. They have been written for maximum clarity without detailed explanations.
　　A second attractive feature of this book is the inclusion of extensive simple, but practical, examples that expose the reader to real-life signal processing problems, which has been made possible by the use of computers in solving practical design problems. This book also covers many topics of current interest not normally found in an upper-division text. Additional topics are also introduced to the reader through problems at the end of Chapters 2 through 14. Finally, the book concludes with a chapter that focuses on several important, practical applications of digital signal processing. These applications are easy to follow and do not require knowledge of other advanced-level courses.
　　The CD accompanying the book also contains several other useful materials, such as files of real signals, review materials, additional examples, a set of frequently asked questions (FAQs), and a short tutorial on MATLAB. Where possible, pointers in the text with CD symbols have been used to direct the reader to relevant materials in the CD. From the feedback we hope to receive from the readers of the thirdedition, we hope to improve the contents on the CD for future editions.
　　The prerequisite for this book is a junior-level course in linear continuous-time and discrete-time systems, which is usually required in most universities. A minimal review of linear systems and transforms is provided in the text, and basic materials from linear system theory are included, with important materials summarized in tables. This approach permits the inclusion of more advanced materials without significantly increasing the length of the book.
　　The book is divided into 15 chapters and an appendix. Chapter 1 presents an introduction to the field of signal processing and provides an overview of signals and signal processing methods.
　　Chapter 2 discusses the time-domain representations of discrete-time signals and discrete-time systems as sequences of numbers and describes classes of such signals and systems commonly encountered. Several basic discrete-time signals that play important roles in the time-domain characterization of arbitrary discrete-time signals and discrete-time systems are then introduced. Next, a number of basic operations to generate other sequences from one or more sequences are described. A combination of these operations is also used in developing a discrete-time system. The problem of representing a continuous-time signal by a discrete-time sequence is examined for a simple case. ..
　　Chapter 3 is devoted to the discrete-time Fourier transform (DTFT) representations of discrete-time sequences. It starts with a short review of the continuous-time Fourier transform (CTFT) representations of continuous-time signals and systems. The DTFT and its inverse are introduced, along with a discussion of the convergence of the DTFT. Properties of the DTFT are next reviewed, and the unwrapping of the phase function to remove certain discontinues in the DTFT is discussed. The concept of the frequency response of a linear, time-invariant (LTI) discrete-time system is then introduced, followed by a careful examination of the difference between phase and group delays associated with the frequency response.
　　Chapter 4 is concerned primarily with the discrete-time processing of continuous-time signals. The conditions for discrete-time representation of a band-limited continuous-time signal under ideal sampling and its exact recovery from the sampled version are first derived. Several interface circuits are used for the discrete-time processing of continuous-time signals. Two of these circuits are the anti-aliasing filter and the reconstruction filter, which are analog lowpass filters. As a result, a brief review of the basic theory behind some commonly used analog filter design methods is included, and their use is illustrated with MATLAB. Other interface circuits discussed in this chapter are the sample-and-hold circuit, the analog-to-digital converter, and the digital-to-analog converter.
　　The major part of Chapter 5 is concerned with the discrete Fourier transform (DFT), which plays an important role in some digital signal processing applications as it can be used to implement linear convolution efficiently using fast algorithm for its computation. The DFT and its inverse are introduced, along with a discussion of their properties. This chapter also includes a review of the discrete cosine transform (DCT) and the Haar transform. All three transforms discussed in this chapter are examples of orthogonal transforms of a finite-length sequence.
　　Chapter 6 is devoted to a discussion of z-transform. The transform and its inverse are introduced, along with a discussion of their properties. The convergence condition of the z-transform is examined in details. It also includes a discussion of the concept of the transfer function of a LTI discrete-time system and its relation to the frequency response of the system.
　　This book concentrates almost exclusively on the linear fime-invariant discrete-time systems, and Chapter 7 discusses their transform-domain representations. Specific properties of such transform-domain representations are investigated, and several simple applications are considered.
　　A structural representation using interconnected basic building blocks is the first step in the hardware or software implementation of an LTl digital filter. The structural representation provides the relations between some pertinent internal variables with the input and the output, which, in turn, provides the keys to the implementation. There are various forms of the structural representation of a digital filter, and two such representations are reviewed in Chapter 8, followed by a discussion of some popular schemes for the realization of real causal IIR and FIR digital filters. In addition, it describes a method for the realization of IIR digital filter structures that can be used for the generation of a pair of orthogonal sinusoidal sequences.
　　Chapter 9 considers the IIR digital filter design problem. First, it discusses the issues associated with the filter design problem. Then, it describes the most popular approach to IIR filter design, based on the conversion of a prototype analog transfer function to a digital transfer function. The spectral transformation of one type of IIR transfer function into another type is discussed. The use of MATLAB in IIR digital filter design is illustrated.
　　Chapter 10 is concerned with the FIR digital filter design problem. A very simple approach to FIR filter design is described, followed by a discussion of a popular algorithm for the computer-aided design of equiripple linear-phase FIR digital filters. The use of MATLAB in FIR digital filter design is illustrated.

　　美国加利福尼亚大学圣·巴巴拉分校Sanjit K. Mitra教授的这本《数字信号处理——基于计算机的方法》，自出版以来，在国内外受到广泛好评。2001年，清华大学出版社引进并影印出版了其第二版，国内有一批大学将其作为“数字信号处理”课程的教材，对推动这门课程的发展，特别是双语教学，起到了积极的作用。.
　　关于Mitra教授本人及第二版的特点，清华大学胡广书教授在第二版的“影印版序”里，已经作了比较充分的介绍，我完全同意他的看法，这里不再赘述。
　　2006年初，Mitra教授推出了本书的第三版。
　　新的版本继承和发扬了前两版讲透基本概念、理论和方法，面向工程和应用的特色，并有新的发展。增加了一些新的内容，删除了一些过时的内容，调整和重新安排了一些章节的内容，订正了一些错误。
　　以下简要介绍第三版和第二版的主要区别。
　　新版将离散时间信号和系统的变换域分析拆成了三章：离散时间傅里叶变换（DTFT）、离散傅里叶变换（DFT）、以及z变换。在DFT一章里，介绍了目前在信号压缩应用里广泛使用的离散余弦变换（DCT）和哈尔（Haar）变换。
　　作为数字信号处理最重要内容之一的无限冲激响应（IIR）和有限冲激响应（FIR）滤波器的设计，在新版里分别单独成章。
　　目前正在发展和应用的多采样率处理问题分成了两章：多采样率处理的基本概念，滤波器组及离散小波变换。
　　有关离散时间随机信号的处理，放到了附录里。
　　新版更加突出了MATLAB的应用。为了便于学生的学习和掌握，作者设计了一种三段式：首先，每章的开头是基本理论和算法；然后，用手工的方法来解例题；最后，用MATLAB来解这些例题。所有例题的MATLAB代码都在书里列出，也收入所附光盘。这样做，非常有利于学生的复习和自学。..
　　多达352个例题（包括163个MATLAB程序）及783个习题（包括158个MATLAB练习），是本书非常突出的特点。
　　对于我们正在强调的自主型和研究型学习来说，这是一本好教材。按照我们的理解，双语教学最重要的目的，是学习和借鉴世界著名大学先进的教学理念和方法，着力培养学生的学习能力和创新意识；对于工科的学生，还要培养学生的工程素养，即应用所学的理论和方法，解决所面临的实际工程问题。当然，还要培养学生使用英语的能力。从这种意义上说，这也是一本好的教材。
　　呈现在读者面前的，是第三版的一个缩编影印本。
　　之所以要缩编，基于两个原因。
　　首先是国外出版社在中国出版影印书的政策使然。
　　第二个原因是，原书适用于本科生和研究生，容量和篇幅都比较大。第三版比第二版又增加了一百多页。对于我国数量众多的本科生来说，无疑是沉重的负担。
　　因此，原书出版社（McGraw-Hill）和清华大学出版社协商，影印出版一本适用于我国本科生学习的缩编版。
　　这次缩编遵循了两个原则，一是只摘去研究生阶段的教学内容，最大限度地保留原书的结构和特色，既是对原书及作者的尊重，也是我们采用原版教材进行双语教学的重要出发点之一；二是符合我国教育部有关教学指导委员会所制定的“数字信号处理”课程的教学基本要求。
　　电子科技大学在本科生和研究生的“数字信号处理”课程里，使用本书的第二版作为双语教学的教材已经多年，数千名本科生和研究生使用过本书。有些学生告诉我，这是他们毕业时不愿意处理掉的书之一。
　　我相信，这本第三版的缩编影印版，将在我们的本科教学里，发挥很好的作用。