05下半年《信号》半期试卷 信号与系统本科试卷

共 5 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 五五 至至 二二 O O 六六 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 2005 年 11 月 5 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 answes justify your answers and write it in the blank 1 The period of is cos 3sin 4x ttt a b is not periodic c d 2T x t3T 4T 2 2 0 122ttdt a 1 b 1 c 0 d 2 3 The closed form expression for illustrated in Figure 1 is t xd a 112233u ttu ttu ttu t b 2233tu ttu ttu t c 112244tu ttu ttu ttu t d Figure 1 112233tu ttu ttu ttu t 4 Let be a periodic signal with fundamental frequency and Fourier series x t 0 coefficients The Fourier series coefficients of is k a 3xt a b c d cannot be ascertained 3 k a 3 k a k a 5 The convolution integral may be 2 2 t y teu t a 2 b 1 c d 2t eu t 2t e 1 1 t 1 x t 02 3 共 5 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 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 7 Consider an LTI system whose input and unit impulse response are x n h n given by 2122x nnnn 11h nnn The output of this system is nhnxny a 2 1 2 3 0 2 1 0 1 2 3 4y nn b 2 1 2 3 0 2 2 1 0 1 2 3y nn c 2 1 2 0 2 2 1 0 1 2y nn d 2 1 2 3 0 2 2 1 0 1 2 3y nn 8 Consider an LTI system with unit impulse response if the dt h tt dt input is illustrated in Figure 2 the output is x t 3 2t y t a 0 5 b 1 c 1 5 d 0 1 10 1 2 2 t x t Figure 2 共 5 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 9 Consider a continuous time LTI system which frequency response is illustrated in figure 3 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 Fourier k a y tx t series coefficients must satisfy k a a b 0 2 k ak 0 2 k ak c d 0 2 0 2 k k a k 0 3 0 3 k k a k 10 Consider an LTI system whose response to the signal is the signal The tx1 ty1 response of the system to the input is tx2 11 Consider a continuous time system with input and output related by x t y t this system may be 2 0 0 0 dx t x t y tdt x t a nonlinear b time invariant c not causal d stable 0 1 H j 5 3 5 3 Figure 3 1 tx 01 t 1 10 1 2 t 1 y t2 x t 011 t 1 10 1 2 t 2 yt 2 1 a 10 1 2 t 2 yt 1 d 10 1 2 t 2 yt 1 c 10 1 2 t 2 yt 3 b 共 5 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 Let be a real periodic signal and The Fourier series of may be x t xtx t x t a b 00 1 2cos k k x taakt 0 1 2sin k k x tjakt c d 0 1 2cos k k x takt 0 1 2sin k k x takt 13 The output of the system to the input is periodic cos2sin10 x ttt 14 Consider a continuous time LTI system whose frequency response is if sin 8 Hj the periodic input signal satisfy the output x t 0y t a with fundamental period T 8 0 xtx t b with fundamental period T 32 0 xtx t c with fundamental period T 16 0 xtx t d with fundamental period T 16 0 xtx t 15 We are given a certain LTI system with unit impulse response and 0 ht Which of the following st