数字信号处理（ Digital Signal Processing ）

数字信号处理（Digital Signal Processing） 信息学院张玉强

Instructor • Zhang YuQiang • E-mail:ya_zyq@yau.edu.cn • Office Phone: 0911-2331506

Textbook • S.K. Mitra, Digital Signal Processing– A Computer-Based Approach, Fourth Ed., McGraw-Hill, 2012 http://www.mhhe.com/engcs/electrical/mitra/

Reference • 高西全，丁玉美等，数字信号处理(第3版),西安电子科技大学，2008.8 • 丁玉美，高西全等，数字信号处理,西安电子科技大学，2005.1 • 丁玉美，高西全等，数字信号处理（第二版）,西安电子科技大学，2001.1 • 胡广书，数字信号处理（第二版），清华大学出版社 1996年 • 奥本汉姆，离散时间信号处理（第一版），西安交通大学出版社 2001年

Reference

Matlab Reference • William J. Palm III, Introduction to Matlab 6 for Engineers, McGraw-Hill, 2001 http://www.mhhe.com/engcs/general/palm/

Requirements • knowledge of linear algebra and calculus • Signals and systems • Basic Matlab programming skills

Content • Introduce • Discrete-Time Signals and systems • Discrete-Time signals and systems in the frequency domain • Finite-length discrete transforms • Fast Fourier Transform (FFT) • Digital filter structure • IIR Digital Filter Design • FIR Digital Filter Design

Grading Policy • Homework – 10% • Experiment– 20% • Midterm Exam - 20% • Final Exam - 50 %

绪论Preface

Preface • What is signal? • A signal is a function of independent variables such as time, distance, position, temperature, pressure and so on.

Preface • What is signal? • Signals play an important role in our daily life. Examples of signals that we encounter frequency: • Speech and music signals represent air pressure as a function of time at a point in space. • A black-and-white picture is a representation of light intensity as a function of two spatial coordinates. • …….

Preface • Why discuss the signal? • The signal carries information. • The objective of signal processing is to extract useful information carried by the signal. • The method of information extraction depends on the type of signal and the nature of information being carried by the signal.

Preface • How do we obtain the desired signal ? • Most signals we encounter are generated by natural means. • A signal can also be generated synthetically or by computer simulation.

Preface • Examples of typical signals A typical electrocardiography (ECG,心电图) trace

Preface One cycle of an ECG waveform

Preface • The electrical activity of the heart is represented by the ECG signal. In practice, there are various types of externally produced artifacts that appear in the ECG signal. Unless these interferences are removed, it is difficult for a physician to make a correct diagnosis.

Preface • Musical sound signal • Examples of typical signals • The electronic synthesizer is an example of the use of modern signal processing techniques.

Preface • Time Series

Preface • Time Series • In many cases, the signals of interest are naturally discrete function of the independent variables. Often such signals are of finite duration. There are many reasons for analyzing a particular time series.

Preface • Images

Preface • The basic problems in image processing are image signal representation and modeling, enhancement, restoration, reconstruction from projections, analysis, and coding.

Preface • How is the signal processing done? • Acquisition (获取） • Analysis（分析） • Transformation（变换） • Synthesis（综合） • Estimate （估值） • Recognition （识别）

Preface • How is the signal processing done? • The method of information extraction depends on the type of signal and the nature of information being carried by the signal. • Signal processing is concerned with the mathematical representation of the signal and the algorithmic operation carried out on it to extract the information present. • Signal processing may be carried out in time-domain or in a transformed domain.

Preface • How Digital Signal Processing? • Circuits • General Computer • Single Chip Computer • DSP Chip

Preface • Various types of signal processing operations are employed in practice. • The desired operations are implemented by a combination of some elementary operations. • How Digital Signal Processing?

Preface • Simple time-domain operations • The three most basic time-domain signal operations are scaling, delay, and addition. • Another elementary operation is the productof two signals. • Two other elementary operations areintegrationand differentiation.

Preface • Filtering • One of the most widely used complex signal processing operations is filtering, whose main objective is to alter the spectrum according to some given specifications.

Preface • Multiplexing(复用） and demultiplexing（解复用）

Preface

Preface • Signal generation • An equally important part of signal processing is synthetic signal generation.

Preface • Why Digital Signal Processing? • Easy adjustment • Less sensitive to tolerances of component values • Reproduced easily • It has been possible to integrate highly sophisticated and complex digital signal processing systems on a single chip. • Realization of certain characteristics not possible with analog implementation.

Preface • Why Digital Signal Processing? • Digital signal processing is also associated with some disadvantages: • Increased system complexity • Limited range of frequencies available for processing • Active devices • finite precision

Preface • Sound recording applications • Compressors and limiters • Expanders noise gates • Equalizers and filters • Noise reduction system • Delay and reverberation(回声） systems • Special effects • Typical Digital Signal Processing Applications

Preface • Musical sound synthesis • Wavetable synthesis • Spectral modeling synthesis • Nonlinear synthesis • Physical modeling synthesis • Typical Digital Signal Processing Applications

DSP Solution

Programmable switch

Mobile phone

The handset is not only used for voice communication

ADSL（Asymmetric Digital Subscriber Line)

audio Digital video LNA DSP BPF BPF ADC Local oscillator Software radio

Digital Camera

HDTV(High Definition TV)

PDP (Plasma Display)TV

数字信号处理（ Digital Signal Processing ）