第五章作业答&aeli

第五章作业答&aeli

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Unformatted text preview: 【 5-13 】解: n n n x   1 sin ] [  的频谱为:              1 1 1 ) ( j e X , 设零值插入后的信号为 ] [ 1 n x ,则       3 3 ] 3 [ ] [ ] [ ) 3 ( 1 k n k n n x n x n x = , 应有, ) ( ) ( 3 1   j j e X e X  ( 1 ) 5 3 1    时, ) ( 1  j e X 的结果如题 5.13 图( a )所示, 频谱在 3 2   k  处,有宽度为 3 2 1  ,幅度为 1 的矩形脉冲。 ] [ 1 n x 经低通滤波后,将保留 ) ( 1  j e X 在   k 2  处的矩形脉冲,滤除其它地方的脉冲, 即 ) ( ) ( ) ( 1    j j j e H e X e W  。 最后对 ] [ n w 进行抽取, ] 5 [ ] [ n w n y  , ] [ n y 的频谱如题 5.12 图( b )所示, 可得 , n n n y   5 3 5 sin ] [ 1  。 ( 2 ) 5 3 1      时,与( 1 )的情况类似, ) ( 1  j e X 的频谱在位于 3 2   k  ,处有宽度为 3 2 1  ,幅度为 1 的矩形脉冲, 这时脉冲宽度的范围为 3 2 ~ 5 2   。 ] [ 1 n x 经低通滤波后,将保留 ) ( 1  j e X 在   k 2  处的矩形脉冲,滤除其它地方的脉冲, 但脉冲宽度被限制在 5    的范围内。 最后对 ] [ n w 进行抽取, ] [ n y 的频谱 ) (  j e Y 将被限制在    的范围内, 即对所有的...
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This note was uploaded on 08/22/2011 for the course EE 201 taught by Professor Yhm during the Spring '05 term at Zhejiang University.

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第五章作业答&aeli

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