信號(hào)與系統(tǒng)作業(yè)答案鄭君里版

1、《信號(hào)與系統(tǒng)》習(xí)題與答案第一章1.1畫出信號(hào)的波形。??)()(sin)(00ttattatf???1.2已知信號(hào)，畫出的波形。??)2()1()1()(?????tututtf)32(??tf1.3已知信號(hào)，試求它的直流分量。??)2()1()1()(?????tututtf答案：01.4已知信號(hào)，試求它的奇分量和偶分量。??)2()1()1()(?????tututtf答案：偶分量：??????)2()1()1(5.0)1()1()

2、1()2()1(5.0?????????????tututtutututut奇分量：??????)2()1()1(5.0)1()1()1()2()1(5.0?????????????tututtututtutut1.5信號(hào)是否是奇異信號(hào)。????20)(ttf00??tt答案：二階以上導(dǎo)數(shù)不連續(xù)，是奇異信號(hào)。1.6已知是有界信號(hào)，且當(dāng)時(shí)，試問是否是能量有限信號(hào)。)(tf??t0)(?tf)(tf答案：不一定。1.7對(duì)一連續(xù)三角信號(hào)進(jìn)行抽

3、樣，每周期抽樣8點(diǎn)，求抽樣所得離散三角序列的離散角頻率。答案：4???1.8以的抽樣間隔對(duì)下列兩個(gè)三角信號(hào)抽樣，寫出抽樣所得離散序列的表達(dá)式，畫出它們的波形。比s5.0?sT較和說明兩波形的差別，為什么？（1）（2）ttf4cos)(1??ttf415cos)(2??答案：兩個(gè)離散序列是相同的。1.9判斷下列信號(hào)是否是周期信號(hào)。如果是周期信號(hào)，試確定其周期。（1）答案：是周期函數(shù)，周期。tCtBtAtf9cos7cos4sin)(???

4、?2?T（2）答案：是周期信號(hào)，周期njdnf8e)(???16?N1.10求下列表達(dá)式的函數(shù)值（1）；答案：?????dttttf)()(0?)(0tf?（2）；答案：?????dttttf)()(0?)(0tf（3）；答案：當(dāng)時(shí)為1；當(dāng)時(shí)為0??????dtttutt)2()(00?00?t00?t（4）；答案：當(dāng)時(shí)為1；當(dāng)時(shí)為0??????dtttutt)2()(00?00?t00?t（5）；答案：???????dtttet)2(

5、)(?2e2?（6）；答案：??????dtttt)6()sin(??216??（7）；答案：?????????dttttetj)()2(0???0e21tj???1.11判斷下列系統(tǒng)是否線性、時(shí)不變和因果（3）；)1()(0??thth)2()(0??txtx答案：)1()(0??tyty（4）；)()(0thth?)()(0txtx??答案：不能確定（5）；)()(0thth??)()(0txtx??答案：)()(0tyty??（6

6、）；)(dd)(0thtth?)(dd)(0txttx?答案：??2)2()()(???ttty??2.4已知一線性時(shí)不變系統(tǒng)對(duì)激勵(lì)的零狀態(tài)響應(yīng)為，求系統(tǒng)的單位沖激響應(yīng))(te???????ttzsetr???d)2(e)()(。)(th答案：()22()(2)d(2)d(2)(2)tttttthteeeeeuteut???????????????????????????或者，變量替換，改寫，由此得??????????2)2(d)(e)

7、(ttzsetr???)2(e)()2(????tutht2.5求下列函數(shù)和的卷積)(1tf)(2tf)()(21tftf?（1），答案：)()(1tutf?)(e)(2tutfat??)(e1tuaat??（2），答案：)1()1()(1????tttf??ttf?cos)(2?)1(cos)1(cos???tt??（3），答案：)()(1ttf??)1()(2??ttf?)1(?t?（4），??)1()()1()(1????tutu

8、ttf)2()1()(2????tututf答案：????22113(1)(1)(2)(2)(3)222tututttutut?????????????????2.6已知和的波形，如題圖2.6所示，繪出的波形。)(1tf)(2tf)()(21tftf?答案：1211()()(2)(2)ftftftft?????第三章3.1求解差分方程（1），，0)2(2)1(3)(?????nrnrnrddd2)1(??dr1)2(??dr012312