The lowpass filter H(u) has a cutoff frequency wc=205T rad/ sec. Thus, c(t)is r(t) where all terms with frequency above we are removed by the lowpass filter. The terms which are kept have kwol 205T rad /sec k|< 10.25, so the output, ac(t),is r(t)= To obtain n, we sample c(t) every T=5 10-3 seconds with an impulse train The sampling frequency is 400T=2 x maximum frequency in c(t). Therefore

Exercise for home study O&W4.47 tea this problem examines the Fourier transform of a continuous-time LTI system with a real, causal impulse response, h(t) (a) To prove that H(w) is completely specified by eh(u) for a real and causal h(t) lore the even part of a function, he(t)

REMINDER: Quiz 1 will be held from 7: 30 to 9: 30 p. m. Tuesday, October 14 The quiz will cover material in Chapters 1-3 of o&w Lectures and Recitations through september 26, Problem Sets 1-3 and that part of Problem Set 4 involving problems from Chapter 3 Reading assignments

REMINDER: Computer Lab #1 is due on October 8 REMINDER: Quiz 1 will be held from 7: 30-9: 30 p. m. Tuesday, October 14 in Walker Memorial. The quiz will cover material in Chapters 1-3 of o W, Lectures and Recitations

Reading Assignments Lectures #5-6& PS#2: Chapter 3 of Oppenheim and Willsky(O& w) Lectures #3-4 &z PS#3: Chapters 3&4 of Oppenheim and Willsky(O&w) Exercise for home study (not to be turned in, although we will provide solutions)

Question: Are there sets of basic\ signals so that a) We can represent rich classes of signals as linear combinations of these building block signals b) The response of ltI Systems to these basic signals are both simp and insightful Fact: For LtI Systems(CT or dt) there are two natural choices for these building blocks Focus for now:

Problems to be handed in: In this lab, you will complete the Basic, Intermediate, and Advanced Exercises for the Echo Cancellation problem considered in Section 2.10 on pages 44-46 of Buck, Daniel, and Singer(BDS). For all of the exercises, please include

Can be continuous Trajectory of a space shuttle Mass density in a cross-section of a brain · Can be discrete dNa base sequence Digital image pixels Can be 1-D,2-D,·N-D For this course: Focus on a single(1-D) independent variable which we call“time

1.已知x(t)<(2),求x1(t)=x(3t-2)e-12的傅立叶变换X() 2.已知x(n)<2X1(z),x2(n)<2X2(z),求x(n)*x2(n)的Z变换X(z) 3.已知x(t)=u(t+1)-u(t-1),x(t)的频谱为X()求x()d2

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