信與系統(tǒng)講義課件

1、信號(hào)與系統(tǒng)講義10,0,0)(ttt1)(d)(tt0) 1 (2201212t)(tp212信號(hào)與系統(tǒng)講義2dttdt)()(dtt)()(t0112112)(1tft21121)(1tf )1()3()1(信號(hào)與系統(tǒng)講義3)(tt0) 1 ()()()()();()0()()(000tttftttftfttf)0()()(fdtttft)(0tt 0) 1 (0t)(0tt t0) 1 (0t)()()(00tfdttttf信號(hào)與系統(tǒng)講義4)()(tt)(1)(taat)(1)(00attatat定義： 稱單位二次沖激函數(shù)或沖激偶。dttdt)()(t)(t)1(0信號(hào)與系統(tǒng)講義5)0()

2、()(fdtttf)()()(00tfdttttf)()0()()0()()(tftfttf)()()()()()(00000tttftttftttf)()(tt信號(hào)與系統(tǒng)講義6)0()()()(fdtttfA)()()()(00tfdttttfB)()()()(00tfdttttfC)0()()()(00fdtttttfDC)()()()()()(000tfdtttfdttttfC信號(hào)與系統(tǒng)講義7)()()(ttA0)()(dttCttdD)()()(B)()()(00ttttB)()()(00ttttB信號(hào)與系統(tǒng)講義8)42()(2tetft)42()42()(22tetetftt解解:)

3、2(5 . 0)2(5 . 042tetet241) 12()2cos(dtttI解解:5 . 0)2cos(5 . 0)5 . 0(5 . 0)2cos(5 . 0241ttdtttI信號(hào)與系統(tǒng)講義9)(1tf101t)(2tf101t)()(21tftf101t2)()(21tftf101t信號(hào)與系統(tǒng)講義10t)(1tf0121112t)(2tf02112t)()(21tftf02112信號(hào)與系統(tǒng)講義11)(tf101t)(tf 01t) 1 () 1 ()()1(tf101t問題問題 1: 能否畫出二階導(dǎo)數(shù)和二重積分的波形能否畫出二階導(dǎo)數(shù)和二重積分的波形?問題問題 2: 能否寫出它們的表

4、達(dá)式能否寫出它們的表達(dá)式?信號(hào)與系統(tǒng)講義12)(tf101t) 1( tf101t) 1( tf101t2f (t-t0)將 f (t) 延遲時(shí)間 t0 ；即將 f (t) 的波形向右移動(dòng) t0 。f (t+t0)將 f (t) 超前時(shí)間 t0 ；即將 f (t) 的波形向左移動(dòng) t0 。)(tf101t)( tf 01t信號(hào)與系統(tǒng)講義13)(tf101t) 1( tf101t2 f (-t-1)= f -(t+1)將 f (-t)的波形向左移動(dòng)1。)( tf 01t) 1(tf01t2反折平移平移反折信號(hào)與系統(tǒng)講義14)(tf101t f (-t+1)= f -(t-1)將 f (-t)的波

5、形向右移動(dòng)1。)( tf 01t反折平移平移反折) 1(tf01t) 1( tf101t信號(hào)與系統(tǒng)講義15壓縮)(tf101t2)2( tf101t25 . 0擴(kuò)展)(tf101t2)(21tf104t2信號(hào)與系統(tǒng)講義16壓縮壓縮反折)22(tf01-t5 . 0平移平移反折平移)22( tf101t5 . 0)(tf101t2)2( tf101t5 . 0)2(tf 01t5 . 0)2( tf101t2信號(hào)與系統(tǒng)講義17反折)(tf101t2反折)2( tf101t2)2(tf 01t5 . 0壓縮)22( tf101t5 . 0平移平移壓縮平移)( tf 101t2)2(tf101t2信

6、號(hào)與系統(tǒng)講義18信號(hào)與系統(tǒng)講義19當(dāng) 0, 即 為d, 而 k 為 。t)(tp0221t)(tf0k)(kf) 0 ( f第個(gè)脈沖函數(shù)：)()0(tpf第K個(gè)脈沖函數(shù)：)()(ktpkfkktpkftf)()()(dtfktpkftfk)()()()(lim)(0先定義窄脈沖信號(hào)：)()(lim0ttp面積為1面積信號(hào)與系統(tǒng)講義20t0)(tf1TTt0)(tfD5 . 0t0)(tfA5 . 05 . 0TT直流分量直流分量交流分量交流分量信號(hào)與系統(tǒng)講義21偶分量的定義為偶分量的定義為 ：)()(tftfee奇分量的定義為奇分量的定義為 ：)()(00tftf任何信號(hào)總可寫成：任何信號(hào)總可

7、寫成：)()()()(21)(tftftftftf)()(21)()(21tftftftf)()(0tftfe)()(21)(),()(21)(0tftftftftftfe即：即：信號(hào)與系統(tǒng)講義22t01)(tf)()(21)(),()(21)(0tftftftftftfet01)( tf t01)(tfet0)(0tft01)(tft021)(tfet0)(0tf21信號(hào)與系統(tǒng)講義23t01)(tft01)( tf t021)(tfet021)(0tft01)( tf )()(21)(tftftfe)()(21)(0tftftf信號(hào)與系統(tǒng)講義24)42(42tt(1)(2)02) 1(4dttt(3)22)5 . 0()cos(8)22()3(dttttt)2(8)2()5 . 0()2(4)2()5 . 0)(4(22tttt0因?yàn)?t+1)位于積分范圍之外。) 1(2)22()3(),1(5 . 0)22(ttttt825 . 0sin82 )cos(825 . 0tt原式信號(hào)與系統(tǒng)講義25)3(4)2()2(2)(2)(ttttttft02)(tf34t01) 1()(ttf)2(t02)(tf 32)4()(),1()(),(tfttftf信號(hào)與系統(tǒng)講義26)22()(1tftf)