11年华科信号系统考题.doc

TEST OF HUAZHONG UNIVERSITY OF SCIENCE TECHNOLOGY (A) Course: SIGNALS SYSTEMS (Closed Book) (2011/06/30) SPECIALTY_________CLASS_________NAME__________No.____________ No. of Questions （Total Score） 1 (20) 2 (30) 3 (15) 4 (15) 5 (20) Total (100) Score (20 points)Choose the proper choice to complete the statement. (2 points for each) Score (a) x(t) is given in Figure 1, it has only ( (3) ). (1) odd harmonics (2) even harmonics (3) dc and sine components (4) dc and cosine components (b) If system S has an input-output equation, then it’s a ( (2) ) system. (1) Linear, Time-invariant, Causal (2) Linear, Time-variant, Causal (3) Linear, Time-invariant, Noncausal (4) Nonlinear, Time-variant, Causal (c) Among the following expression, ( (1) ) doesn’t represent the step sequence. (1) (2) (3) (4) (d) The result of is ( (3) ). (1) (2) (3) (4) (e) Let B1 be the frequency band width of signal, B2 be the frequency band width of signal , then ( (1) ). (1) B1 = 6 B2 (2) B1 = B2 / 3 (3) B1 = 3 B2 (4) B1 = B2 / 2 (f) If all the poles of the system function of an LTI system lie on the left side of jω-axis, then the system ( (4) ). (1) must be both stable and causal (2) must be stable (3) must be causal (4) all the former choices are wrong (g) A continuous-time LTI system has a system function, then it’s a ( (2) ) filter. (1) low-pass (2) high-pass (3) band-pass (4) band-stop (h) The inverse z-transform ofis ( (3) ). (1) (2) (3) (4) (i) Among the following statement, ( (4) ) is wrong. (1) The nature response of an LTI system has nothing to do with input signal (2) For an LTI system, the nature response has the same mode with zero-input response (3) The forced response is generally not equal to the zero-state response, but part of it (4) We take use of the initial state values of time instant to determine the n