06-07（1）《信号》半期试卷 信号与系统本科试卷

共 4 页 第 1 页 学院 任课教师 班次 学号 选课号 姓名 密 封 线 内 答 题 无 效 电电 子子 科科 技技 大大 学学 二二 O O 六六 至至 二二 O O 七七 学年学年 第一学期 阶段测试 第一学期 阶段测试 SIGNALS AND SYSTEMS 课程考试试题 120 分钟 考试日期 2006 年 11 月 12 日 一二三四五六七八九十总分评卷教师 Attention each of the following questions may have more than one right answers justify your answers and write it in the blank 1 0 cos222 ttdt a 1 b 1 c 0 5 d 0 5 2 The period of is cos 2sin 2 x nnn a b is not periodic c d 2 N x n3 N4 N 3 The convolution integral may be cos t y tt e u t a b c d cos 4 t 1 cos 4 2 t 1 cos 4 2 t cos 4 t 4 The closed form expression for illustrated in Figure 1 is dx t dt a 23 u ttt b 33 u ttt c 213 u ttt d Figure 1 13 u ttt 5 Let be a periodic signal with fundamental frequency and Fourier series x t 0 coefficients The Fourier series coefficients of is k a 23 x t a b c d 2 k a 0 3 1 2 j k ke a 0 3 j k ke a 0 3 2 j k ke a 1 t 1 x t 023 共 4 页 第 2 页 学院 任课教师 班次 学号 选课号 姓名 密 封 线 内 答 题 无 效 6 Consider an LTI system whose input and unit impulse response are x n h n given by 1212 x nu nnu n 11 h nnn The output of this system is nhnxny a 1 0 1 0 1 2 1 0 1 2 y nn b 1 0 0 0 1 2 1 0 1 2 y nn c 1 0 0 0 1 1 0 1 2 3 y nn d 1 0 1 0 1 2 1 0 1 2 y nn 7 Let may be 1x tu tu t 2h tx t y tx th t a 11223344tu ttu ttu ttu t b 112233tu ttu ttu ttu t c 11223344tu ttu ttu ttu t d 112233tu ttu ttu ttu t 8 Consider an LTI system with unit impulse response if the input t h te u t the output is dt x tt dt y t a b c d t dt dt t e u tt t 9 Consider an LTI system with unit impulse response if 12h tu tu t the input is illustrated in Figure 2 the output is x t 0t y t a 0 5 b 1 c 1 5 d 0 1 10 1 2 2 t x t Figure2 共 4 页 第 3 页 学院 任课教师 班次 学号 选课号 姓名 密 封 线 内 答 题 无 效 10 Consider an LTI system whose response to the signal is the signal If the input 1 21122 x ttu ttu ttu t 1 cos y ttu t is illustrated in figure 3 the output is 2 xt 2 yt a 2 cossinyttu ttt b 2 sincosyttu ttu t c 2 cosytu tt d 2 sinyttu tt 11 Consider a continuous time LTI system which frequency response is illustrated in figure 4 When the input to this system is a periodic signal with fundamental x t period T 1 and Foureier series coefficients it is found The input k a y tx t signal must satisfy x t a b 0 0 0 0 k k a k 0 0 k ak c d 1 2 1 2 0 x t dt 1 2 0 0 x t dt 12 Consider a continuous time system with input and output related by x t y t this system may be 2 1y tx tx t a linear b time invariant c not causal d stable 11 Consider a continuous time system with input and output related by x t y t this system may be cos22 y ttx t a linear b time invariant c causal d not stable 0 1 H j Figure 4 0 1 t 1 2 2 x t 1 Figure 3 共 4 页 第 4 页 学院 任课教师 班次 学号 选课号 姓名 密 封 线 内 答 题 无 效 12 Determine which of the following signals wish finite total energy a b t x te u t cosx ttu t c d t x te u t cos2x tt u tu t 13 The output of the system to the input is not cos2sin5cos10 x tttt periodic 14 Consider a continuous time LTI system whose frequency response is sin 2 Hj When the input to this system is it is found Which of the following 0 jt x te 0y t statements is ture a b c d 0 2 0 0 3 0 4 15 We are given a certain LTI system with unit impulse response and 0 ht Which