D.相位的影响:4X(j0) 线性相位(-(-00)=0)增加时延 Xo)lel14x gjo) IX(ole j[4X(o)fot 时移特性 X(j)>x() X(im)aJ0∠F1 >x(t-to) 实函数 时间反转 X(j0) F x(t X(-jO)<>x(-1) X(ole ∠H(iO Ix(o)le j<x Jjo) 奇对称 偶对称 d△Y(j) 时延 d△Y(jo 时延 d ProfJianyu Yang:Understanding of Signals Systems
D. 相位的影响: X j ( ) ( ) | ( ) | j X j X j e time ⎯⎯⎯→ reversal 1 ( ) ( ) F X j x t − − ⎯⎯→ − ( ) | ( ) | j X j X j e − 1 ( ) ( ) F X j x t − ⎯⎯→ ( ) | ( ) | j X j X j e time shifting ⎯⎯⎯⎯→ 1 0 0 ( ) ( ) j t F X j e x t t − − ⎯⎯→ − 1 ( ) ( ) F X j x t − ⎯⎯→ 0 [ ( ) ] | ( ) | j X j t X j e − 0 0 ( ( ) ) d linear phase t t d − − = d X j ( ) Delay : d − d X j ( ) Delay : d 线性相位 增加时延 时移特性 实函数 时间反转 偶对称 奇对称 时延 时延
k x(t)=1+- cos(2Tt +p)+cos(4It +2)+- cos(6It+P3) x(1)=∑xe jk2It e a e a e 4 -1a22 e a e g内}—>x的不同波形 <P303,图61> ProfJianyu Yang:Understanding of Signals Systems
<P303 , 图6.1> 1 2 3 1 2 ( ) 1 cos(2 ) cos(4 ) cos(6 ) 2 3 x t t t t = + + + + + + 1 2 3 ⎯⎯→ x(t)的不同波形 2 ( ) k jk t k x t x e + =− = 1 2 3 1 2 3 jφ jφ jφ 0 1 2 3 -jφ -jφ -jφ -1 -2 -3 1 1 1 a =1; a = e ; a = e ; a = e 4 2 3 1 1 1 a = e ; a = e ; a = e 4 2 3
Φ1=Φ,=Φ2=0 Φ1=4,Φ2=8,3=12 ∧AA ①,=6①,=-27,=093 ^NN、m ProfJianyu Yang:Understanding of Signals Systems
1 = 2 = 3 = 0 1 = 4,2 = 8,3 =12 1 = 4,2 = 8,3 =12 6, 2 .7, 0.93 1 2 3 = = − = 1.2, 4.1, 7.2 1 2 3 = = = −
P304 I P(On,jo2) ∠P(2JO2) ProfJianyu Yang:Understanding of Signals Systems
1 = 4,2 = 8,3 =12 | ( , )| 1 2 P j j ( , ) 1 2 P j j P304
P305 幅度:|P(jOn,jO2) 相位:0 幅度:1 相位:∠P(jon,jO2) of Jianyu Yang: Understanding k Systems
1 = 4,2 = 8,3 =12 P305 : 0 :| ( , )| 1 2 相位 幅度 P j j : ( , ) :1 1 2 相位 P j j 幅度