【正文】 064 2/)4( tt1t4 6??? ???????其它 0422 2/)22()2(tttf??? ???其它 020 2/ tt1t20f ( t? 2 ) f(t?t0)， 表示信號(hào) f(t)右移 t0單位； f(t?t0)， 表示信號(hào) f(t)左移 t0單位。 若 a1， 則 f(at)是 f(t)的壓縮。 – Ramp Signal 斜變信號(hào) – Unit Step Signal單位階躍信號(hào) – Signum Function符號(hào)函數(shù) – Unit Impulse Signals單位沖激 Unit Ramp Signal 單位斜變信號(hào) 0 1 t 0 t0 t0+1 t R(t) R(tt0) t =0 R(t) = t t 0 R(t) = 0 t t0 R(tt0) = 0 t = t0 R(tt0) = t t0 Unit Step Signal 單位階躍信號(hào) ????????02100010)(tttttttt?1 ???????00100)(21 tttt?t 0 t0 1 epsilon 用階躍表示門信號(hào) )2()2()( ????? ???? tttp )2()2()( 000????? ??????? ttttttp2?2?? t t 0t（ 1）突然接入的直流電壓 （ 2）突然接通又馬上斷開電源 K 負(fù)載 Signum Function 正負(fù)符號(hào)函數(shù) Definitions sgn(t) 1 0 t Interpret by Step Signal 1 ?????)0(1)0(1)s gn(ttt1)(2)s gn( ?? tt ?Conclusions 1. We are awash in a sea of signals. 2. Signal categories identity of independent variable, dimensionality, CT or DT, real or plex, periodic or aperiodic, causality, bounded, even amp。 ? 隨機(jī)信號(hào)：在任何時(shí)刻的取值都是隨機(jī)的、不確定，信號(hào)發(fā)生前不能準(zhǔn)確預(yù)測(cè)信號(hào)的取值。 如果給定任一時(shí)間，信號(hào)的值是隨機(jī)的，換句話說，信號(hào)的未來值不能用準(zhǔn)確的時(shí)間函數(shù)式來描述，無法準(zhǔn)確地預(yù)測(cè)，在相同的條件下也不能準(zhǔn)確地重現(xiàn)，則稱該信號(hào)為 不確定信號(hào)或隨機(jī)信號(hào) 。 21 /TT 為無理數(shù)時(shí)，則是非周期函數(shù)。 一段語音信號(hào) (―對(duì)了” ) 。信息的傳輸體現(xiàn)在信號(hào)變化之中，信號(hào)是任何運(yùn)動(dòng)或狀態(tài)變化的反映。Classification of signals ?Operations on signals ?Description amp。Signals amp。 Systems信 號(hào) 與 系 統(tǒng) CHAPTER 1 INTRODUCTION Contents ?Description amp。Classification of systems Why Study the course —— Signals and Systems ? Purpose This subject is about using mathematical techniques to help analyze and synthesis systems which process signals. The purpose of this course is to prove a mon background for subsequent courses in control, munications, electronic circuits, filter design, and digital signal processing. What? What is a signal? What is a system? The signals , which are functions of one or more independent variables, contain information about the behavior or nature of some physical phenomena, whereas the systems respond to particular signals by producing other signals or some desired 15 The interaction between a system and its associated signals is illustrated in the following schematic diagram: System Input signal Output signal Transmit or process f(t) y(t) ? A signal is formally defined as a function of one or more independent variables that contains information about some physical phenomena. ? A system is formally defined as an entity that manipulates one or more signals to acplish a specific function. How? ?Curriculum Characteristic and Study Method ?References ?Study Arrangement Curriculum Characteristic and Study Method ： 物理概念、數(shù)學(xué)概念和工程概念并重 著重掌握信號(hào)與系統(tǒng)分析的 基本思想 和 方法 注意 問題的提出 、 分析問題 和 解決問題 的方法 :理論與實(shí)際相結(jié)合，講、練、做相結(jié)合 ? 作業(yè) ? 計(jì)算機(jī)實(shí)踐： MATLAB是信號(hào)分析與處理的強(qiáng)大工具 REFERENCES (1). Oppenheim, 劉樹棠譯， 《 信號(hào)與系統(tǒng) 》 ,西安交通大學(xué)出版社， 2022 (2)Hwei , 駱麗，胡健，李哲英譯， 《 信號(hào)與系統(tǒng) 》 ，科學(xué)出版社， 2022 (3)鄭君里等 ,《 信號(hào)與系統(tǒng) 》 ，第 2版 , 高等教育出版社， 2022 (4)胡光銳等， 《 信號(hào)與系統(tǒng)解題指南 》 ，科學(xué)出版社， 2022 (5)閔大鎰，張慶孚編， 《 信號(hào)與系統(tǒng)自學(xué)輔導(dǎo)與應(yīng)試指南 》電子科技大學(xué)出版社， 1999 Study Arrangement ? 預(yù)習(xí) +聽課 +復(fù)習(xí) ? 書面作業(yè) (按時(shí) ) ? 平時(shí) 30%+期末考試 70%