电子科大2010年信号与系统期末考题及标准答案.doc

学院 姓名 学号 任课老师 选课号/座位号 密封线以内答题无效电子科技大学二零 一 零 至二零 一 一 学年第 一 学期期 末 考试 SIGNALS AND SYSTEMS 课程考试题 A大纲A 卷 （ 120 分钟） 考试形式： 一页纸开卷 考试日期 20 年 月 日课程成绩构成：平时 10 分， 期中 20 分， 实验 10 分， 期末 60 分一二三四五六七八九十合计复核人签名得分签名Attention: You must answer the following questions in English.1.（15 points） Suppose and are two band-limited signals, where,.Impulse-train sampling is performed on to obtain .Give out the expression of in terms of and ，where is the Fourier transform of . Specify the largest values of the sampling period T which ensures that is recoverable from .2.（20 points）Consider a stable system illustrated in Figure 1, if we know ， , and the input ，determine the output . Figure 13. ( 10 points ) Determine the function of time, , for the Z transform and its associated regions of convergence: 4.（15 points）Consider a system illustrated in Figure 2(a). The input signal has the Fourier tansform shown in Figure 2(b), and the output signal has the Fourier tansform shown in Figure 2(c). Determine a possible system S. Figure 2(a)SFigure 2(b)Figure 2(c)5.(20 points) Consider a LTI system with unit impulse response ,where is an unknown constant.When the input to the system is ,the output is .(a) Determine the system function of the system and sketch the pole-zero pattern, then indicate the ROC of .(b) Is this system causal and stable ?(c) Draw a block diagram representation of this system.6.(20 points) A stable LTI system is described by the difference equation .(a) Find the system function, sketch the pole-zero pattern of , then indicate the ROC of .(b) Determine the unit impulse response. Is this system causal?(c) Compute the output of this system, if the input signal is .电子科技大学2010-2011-1期 末 考试信号与系统（A大纲A卷） 参考解答1.(15 points) Solution: , , (second) 2. (20 points) Solution: 3. (10 points) Solution: 4. ( 15 points ) Solution: 5.(12 points) Solution:(a) (b) The system is causal and stable. S-1S-1-4-324(c)6.( 20 points ) Solution:1/4 1/2-2