电子科大课堂版chap1汇编

1、Signals & SystemsSecond Edition 电子工程学院 孔斌 邮箱： 地址：科C307右1电子电路类电路分析基础模拟电路基础数字逻辑设计及应用电子技术实验基础集成电路应用实验现代电子技术综合实验电子信息工程综合实践电磁场与微波类电磁场与波微波技术基础计算机类软件技术基础微机原理与应用信号与信息类信息论导论信号与系统数字信号处理通信技术与系统制图与控制类现代工程设计制图自动控制原理专业基础虚拟仪器基础实验单片机原理及接口MATLAB工具软件EDA技术DSP技术高级语言随机信号分析PCA技术物理电子类量子力学与物理电子学固体电子学半导体物理2课程说明教学计划学时: 80 学分

2、: 5教学内容课堂理论教学(68学时)实验(8学时)课堂习题课(4学时)考核方式平时10%+半期20%+上机实验10%+期末60%3课程说明参考书目: Exploration in Signals and Systems Using MATLAB John R.Buck , Michael M. Daniel 刘树棠 译，西安交通大学出版社 信号与系统分析 吕幼新 张明友 电子工业出版社 信号与系统复习考研例题详解 吕幼新 张明友 电子工业出版社4课程说明1. 课件下载（密码：2012）校园网网络课堂电子工程学院孔斌课件发布3. 作业要求 用中、英文书写; 每章完成后交作业;校园网精品课程信号

3、与系统2. 网络教学资源5Chapter 1 Signals and Systems6Chapter 1 Signals and Systems 1.1 Continuous-Time and Discrete-Time Signals1.2 Transformations of the independent variable 1.3 Exponential and Sinusoidal Signals 1.4 The Unit Impulse and Unit Step Functions 1.5 Continuous-time and discrete-time systems 1.6

4、Basic System Properties7Chapter 1 Signals and Systems(1) A simple RC circuitInput: Vs Output: Vc(2) An automobilevfInput: f Output: v8(3) A Speech SignalChapter 1 Signals and Systems9(4) A PictureChapter 1 Signals and Systems10(5) Vertical Wind ProfileChapter 1 Signals and Systems11信号的描述频率特性信号可表示成一个

5、或多个自变量的函数;电压电流信号与系统分析的两个共同的基本点：2. 系统：对给定的信号作出响应，并产生新的信号Chapter 1 Signals and Systems1. 信号（一个或多个自变量）时间特性12 1.1 Continuous-Time and Discrete-Time Signals连续时间信号和离散时间信号 1.1.1 Examples and Mathematical RepresentationContinuous-Time Signals The independent variable is continuous0 t0 tChapter 1 Signals and

6、 Systems13Chapter 1 Signals and Systems2. Discrete-Time Signals The independent variable is discreten is integer numberContinuous-time signalsDiscrete-time signals14Chapter 1 Signals and SystemsTime-averaged power（平均功率） Energy signal0 t0 t Power signal0 tInstantaneous power（瞬时功率）Total energy 1.1.2 S

7、ignal Energy and Power15Chapter 1 Signals and Systems1.2 Transformations of the independent variable1.2.1 Examples of transformations of the independent variable1. Time shift( 时移)Example 10 otherwisePlease indicate 16Chapter 1 Signals and Systems 与 波形相同相当于 左移（超前） to2. Time reversal( 时域反折)x(-t) is a

8、reflection of x(t) about t=0相当于 右移（延迟） to时移对信号的影响173. Time- scaling( 尺度变换)Chapter 1 Signals and Systemsa1 信号压缩a倍0a1 信号扩展 1/ a 倍 Continuous- time signals Discrete- Time signals x an n, an Nxn18Chapter 1 Signals and Systems0 1 2 t1SolutionExample 1.1 Determine the signal-2/3 0 2/3 t1191.2.2 Periodic s

9、ignalsChapter 1 Signals and SystemsSynthesize the signals periodicT1T2当T1/T2为有理数时， 为周期的其中 n1,n2 互质其周期20Chapter 1 Signals and Systems 1.2.3 Even and Odd SignalsEven partOdd part0 1 2 t121Chapter 1 Signals and Systems 1.3 Exponential and Sinusoidal Signals指数信号和正弦信号 1.3.1 Continuous-Time Complex Expone

10、ntial and Sinusoidal Signals1. Real Exponential Signalsa is real22Chapter 1 Signals and SystemsPeriodic Complex Exponential and Sinusoidal Signals Period Euler s relation Average Power Harmonic relation3. General Complex Exponential Signals 23Chapter 1 Signals and Systems24Chapter 1 Signals and Syst

11、ems 1.3.2 Discrete-Time Complex Exponential and Sinusoidal Signals1. Real Exponential Signals real25Chapter 1 Signals and Systems2. Complex Exponential Signals and Sinusoidal Signals Average Power Euler s relation Periodicity Properties Harmonic relation Frequency Properties 3. General Complex Expon

12、ential Signals 26Chapter 1 Signals and SystemsFigure 1.270=2 k 时, 信号频率低0=(2 k+1) 时, 信号频率高270不同,信号不同. 0相差2 k,信号相同. 0越大,频率越高.0 =2 k 时,频率低; 0 =(2 k+1)时,频率高.对任意的0,信号均为周期的. 为有理数时, 信号为周期的.Chapter 1 Signals and Systems28Chapter 1 Signals and Systems 1.4 The Unit Impulse and Unit Step Functions单位冲激（脉冲）与单位阶跃

13、函数 1.4.1 The Discrete-Time Unit Impulse and Unit Step SequencesUnit Impulse n=00 n 0Unit Stepn 00 n 00 t 00 t10 t12. Unit Impulse Function1C+-t=031Chapter 1 Signals and Systems0 t 0If32Chapter 1 Signals and Systems 1.4.3 The Properties of Unit Impulse Functions1. Sampling and Sifting propertiesIf f(

14、t) is continuous at the point of t=0Sampling property Sifting propertyScaling propertyIf a is real, a 033Chapter 1 Signals and SystemsExample2 34Chapter 1 Signals and Systems 1.4.4 信号的计算1. 信号的加、减、乘2. 信号的基本表示- 0 t0 1 t 1-1 0 1 t13. 信号的微分、积分运算35Chapter 1 Signals and SystemsExample 1.7 x(t) is depicted

15、 in Figure 1.40(a),determinethe derivative of x(t). 2 1 0 1 2 3 4 t-1x(t)36Chapter 1 Signals and Systems 1.5 Continuous-time and discrete-time systemsSystem Be constituted by some unitsContact with some rule The systems functionSystem analysis （系统分析）System synthesizes （系统综合）Research system37Chapter

16、1 Signals and Systems 1.5.1 Simple Examples of SystemsExample 1.9Linear constant-coefficient differential equation Example 1.838Chapter 1 Signals and SystemsContinuous-Time System Discrete-Time System N-order Linear Constant-coefficientDifferential Equation N-order Linear Constant-coefficientDiffere

17、nce Equation 39Chapter 1 Signals and Systems 1.5.2 Interconnection of SystemsSeries interconnection(级联)Parallel interconnection(并联)Feedback interconnection(反馈)System 1System 2inputoutputSystem 1System 2inputoutputSystem 1System 2inputoutput40Chapter 1 Signals and Systems 1.6 Basic System Properties

18、1.6.1 Systems with and without Memory有记忆、无记忆系统无记忆系统: 在任意时刻(t)的输出仅仅与同时刻(t)的输入有关。 memoryless（无记忆）identity system ,memoryless summer delay integrateSystems with memory41Chapter 1 Signals and Systems 1.6.2 Invertibility and Inverse Systems可逆系统与可逆性可逆系统: 不同的输入导致不同的输出（一一对应）。 SystemInverse System noninverti

19、ble systems不可逆系统42Chapter 1 Signals and Systems 1.6.3 Causality （因果性）因果系统: 在任意时刻(t)的输出只取决于同时刻(t)或以前(t) 的输入。 (与该时刻以后的输入无关） Systems without memory Causal systems因果系统不可预测系统物理上可实现43Chapter 1 Signals and Systems非因果系统: 适用于非时间自变量信号的处理.Not Causal 1.6.4 Stability （稳定性）Stable System not stable stable44Chapter

20、 1 Signals and Systems 1.6.5 Time Invariance （时不变性）时不变系统: 系统参数不随时间改变(恒参系统),系统的输出波形仅仅取决于输入波形,而与输入作用的时刻无关.If Time invariant时不变 Example 1.14Example 1.15Example 1.1645Chapter 1 Signals and SystemsContinuous-Time System Discrete-Time System N-order Linear Constant-coefficientDifferential Equation N-order

21、 Linear Constant-coefficientDifference Equation 46Chapter 1 Signals and Systems 1.6.6 Linearity （线性）1. Initial State （初始状态）2. Linearity Additivity Scaling 3. Linear System47Chapter 1 Signals and SystemsExample 1.17Example 1.18Example 1.19Example 1.2048Chapter 1 Signals and Systems线性系统线性系统的三个特性 微分特性

22、积分特性频率保持性：信号通过线性系统不会产生新的频率分量49Example 1 an LTI system0 2 t10 1 2 t1L0 2 4 t1-10 2 4 t1LChapter 1 Signals and Systems50 1.1 Continuous-Time and Discrete-Time Signals1.2 Transformations of the independent variable 1.3 Exponential and Sinusoidal Signals 1.4 The Unit Impulse and Unit Step Functions 1.5 Continuous-time and discrete-time systems 1.6 Basic System Properties51Chapter 1 Signals and Systems作业：1.14 1.15 1.16 1.171.21 (d) (e) (f) 1.22 (d) (g) 1.23 1.24 (a) (b) 1.26 (a) (b) 1.27 1.3152Classification of signals （信号的分类）1.Continuous Time（CT）and discrete time（DT） signals 连续时间