山东大学2017-2018学年2学期数字信号处理（双语）课程试卷(A)答案与评分细则 Since is periodic with period N,and W=W 元内=（1+e+e4） (（1+e-2)+e2()）k/3 3k/3,k=3 = 0, otherwise (b)Using N=2 andn]as in the Fig : 树= 时 R-0 = * n=0 0+0e“ =1+2(-1) 3,k=0 -1,k=1 Observe,from the Fig,that n]is also periodic with period 3N=6: 3N-1 内= nw缺 5 = “ n-0 =(1+e*+e-w)1+2(-1)) =(1+e*+e-)/3例 器 9,k=0 -3,k=3 0,k=1,2,4,5 第3负共3项2017-2018 2 数字信号处理（双语） （A）答案与评分细则 3 3