第05章 离散时&eacut

&ccedil&not - Chapter 5 transform analysis of linear time-invariant system 5.1 the frequency response of LTI system 5.2 system function 5.3

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5.1 the frequency response of LTI system 5.2 system function 5.3 frequency response for rational system function 5.4 relationship between magnitude and phase 5.4 relationship between magnitude and phase 5.4 relationship between magnitude and phase 5.5 all-pass system 5.6 minimum-phase system 5.7 linear system with generalized linear phase Chapter 5 transform analysis of linear time-invariant system
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5.1 the frequency response (频率响应) of LTI system | ( )| | ( ( )| () jjj Ye Xe He ωωω ω ωω =⋅ =+ ((( We can express the frequency response in polar form: For LTI system, the Fourier transform of the system input and output are related by jj j Xe He = The definition of the frequency response is: −∞ = ω ω = n n j j e n h e H ] [ ) ( | | j j H e e = )
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| ) ( | . 1 ω j e H magnitude response (幅度响应或增益) ) ( ) ( | ) ( | . 2 2 j j j e H e H e H = magnitude square function (幅度平方函数) dB unit e H j : |, ) ( | log 20 . 3 10 log magnitude or gain in dB (对数幅度, dB 计的增益) | ) ( | log 20 10 j e H Attenuation in dB (以 dB 计的衰减) Define: (幅频特性)
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对数幅度 线性幅度 线性到对数 的转换曲线 -8dB 0.4 线性幅度 1 0.1 0.01 0.001
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4. ( ) j He ω ) phase response (相位响应,相移): ambiguous π < )] ( [ . 5 j e H ARG principal value phase (主值相位) d e H d e H grd j j )] ( arg[ )] ( [ . 7 = Group delay (群延迟:对相位特 性线性程度的一种度量) )] ( arg[ . 6 j e H continuous phase (连续相位): continuous function of ω Define: (相频特性)
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Figure 5.7 arg[ ( )] ( ) 2 j He r ω π = −⋅ a r g [ () ] [ ] jj ARGHe ωω 的关系
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Figure 5.1 EXAMPLE 0.25 0.5 0.85 π ππ c ω the effects of attenuation and group delay
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Figure 5.2 π ω 5 . 0 , 25 . 0 , 85 . 0 = 25 . 0 , 5 . 0 = 0.25 0.5 0.85 ππ 群延迟 50 群延迟 200 总结 5.1 对数幅度, 群延迟, 物理意义
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5.2 system function (系统函数) −∞ = = n n z n h z H ] [ ) (
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This note was uploaded on 02/29/2012 for the course EE 325 taught by Professor Lilili during the Fall '11 term at BYU.

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&ccedil&not - Chapter 5 transform analysis of linear time-invariant system 5.1 the frequency response of LTI system 5.2 system function 5.3

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