信息与通信工程专业英语ch.3PPT格式课件下载.ppt

1、Chapter 3 Signal System&#Signal Processing2009年8月28日6时56分电子信息与通信工程专业英语3.1 Signal and System3.2 Digital Signal Processing3.3 Speech Signal Processing2009年8月28日6时56分电子信息与通信工程专业英语TEXT 3.1 Signal and SystemSimply introduction of the mathematical representations of continuous-time and discrete-time signa

2、ls and systems,and the concepts of signal energy and power.2009年8月28日6时56分电子信息与通信工程专业英语1.Continuous-time and discrete-time signals2.Continuous-time and discrete-time systems3.Some properties of digital signal system4.Signal energy and power2009年8月28日6时56分电子信息与通信工程专业英语TerminologyTerminologyaeronautic

3、s n.航空学,航空术astronautics n.太空航空学seismology n.地震学meteorologic adj.气象的,气象学的profile n.剖面,侧面,外形,轮廓convention n.大会,协定,习俗,惯例terminology n.术语学electromechanical adj.机电动机械的,机电的,电机的automotive adj.汽车的,自动推进的vehicle n.交通工具,车辆high-fidelity 高保真tone n.音调,音质,语调2009年8月28日6时56分电子信息与通信工程专业英语1.Continuous-time and discret

4、e-time signals Signals are represented mathematically as functions of one or more independent variables:#eg.1:#a speech signal can be represented mathematically by acoustic pressure as a function of time 2009年8月28日6时56分电子信息与通信工程专业英语eg.2 a picture can be represented by brightness as a function of two

5、 spatial variables 2009年8月28日6时56分电子信息与通信工程专业英语To distinguish between continuous-time and discrete-time signals,we will use the symbol t to denote the continuous-time independent variable which is enclosed in parentheses（.）and n to denote the discrete-time independent variable in brackets.2009年8月28日

6、6时56分电子信息与通信工程专业英语 Illustrations of a continuous-time signal and a discrete-time signal are shown in Fig.3-4.（a）（b）Fig.3-4 Graphical representations of（a）continuous-time and（b）discrete-time signals 2009年8月28日6时56分电子信息与通信工程专业英语Physical systems in the broadest sense are an interconnection of component

7、s,devices,or subsystems.In context ranging from signal processing and communications to electromechanical motors,automotive vehicles,and chemical-processing plants,a system can be viewed as a process in which input signals are2.Continuous-time and discrete-time systems2009年8月28日6时56分电子信息与通信工程专业英语tra

8、nsformed by the system or cause the system to respond in some way,resulting in other signals as outputs.For example,a high-fidelity system takes a recorded audio signal and generates a reproduction of that signal.If the hi-fi system has tone controls,we can change the tonal quality of the reproduced

9、 signal 2009年8月28日6时56分电子信息与通信工程专业英语（a）continuous-time systemy（t）x（t）h（t）y（n）x（n）h（n）Fig.3-5 Two kinds of system（b）discrete-time systemIt is important to note that the discrete-time signals defined only for integer values of the independent variable.2009年8月28日6时56分电子信息与通信工程专业英语 A continuous-time sys

10、tem is a system in which continuous-time input signals are applied and result in continuous-time output signals.As in Figure 3-1-5（a）,where x（t）is the input,y（t）is the output,and h（t）is the system impulse response.2009年8月28日6时56分电子信息与通信工程专业英语Similarly,a discrete-time systemthat is,a system that tran

11、sforms discrete-time inputs into discrete-time outputsis depicted as in Figure 3-1-5（b）.Where x（n）is the input,y（n）is the output,and h（n）is the system unit sample response.2009年8月28日6时56分电子信息与通信工程专业英语We can bring continuous-time and discrete-time systems together through the concept of sampling,and

12、we can develop some insights into the use of discrete-time systems to process continuous-time signals that have been sampled.2009年8月28日6时56分电子信息与通信工程专业英语At present,many digital signal processing methods have been widely used in science and technology fields.So we take digital signal system for examp

13、le,some system properties are described in next section.2009年8月28日6时56分电子信息与通信工程专业英语3.Some properties of digital signal systemThe linearity of a systemTime invariance of a system is defined asLinearity and time invariance are independent properties.2009年8月28日6时56分电子信息与通信工程专业英语Communtative:#Associati

14、ve:#Distributive:#2009年8月28日6时56分电子信息与通信工程专业英语4.Signal energy and powerSignals with finite total energy,i.e.,signals for which Such a signal must have zero average power.signals is those with finite average power signals is the signals for which neither nor are finite.2009年8月28日6时56分电子信息与通信工程专业英语EXE

15、RCISES1.Please translate the following words and phrases into Chinese.2.Please translate the following words and phrases into English.2009年8月28日6时56分电子信息与通信工程专业英语TEXT 3.2 Digital Signal Processing1.Introduction2.Fourier Analysis3.FIR digital filter design4.Window Functions2009年8月28日6时56分电子信息与通信工程专业英

16、语Terminologyfidelity n.保真度,（收音机,录音设备等的）逼真度,保真度,重现精度sensory adj.感觉的,感官的seismic adj.地地震的vibrations n.振动,颤动,摇动,摆动storage n.贮藏（量）,贮藏库,存储superposition n.重叠,重合,叠合ubiquitous adj.到处存在的,（同时）普遍存在的utility n.效用,有用2009年8月28日6时56分电子信息与通信工程专业英语symmetry n.对称,匀称weight function 权值函数approximate v.近似,接近,接近,约计integral n.数学 积分,完整,部分sparse matrice 稀疏矩阵invariant adj.无变化的,不变的 Fourier series 傅立叶级数recursive adj.回归的,递归的even function 偶函数interval n.间隔 non-recursive 非回归的，非递归的finite-duration 有限长时间2009年8月28日6时56分电子信息与通信工程专业英语physical