信號與系統(tǒng)-華南理工大學(xué)期末考試試卷2009A

1、 Signals and Systems 試卷 A一、 填空題（4分/每題，共20分）1. A system has inputand output . If the system has properties, then the input and output pairs has the relationship: input is, so output is 。2. Consider sampling ，determine the maximum of sampling interval T so that there will be no aliasing, (s).3. Write

2、or Sketch the spectrum of Rectangular pulse xn: There is the inverse relationship between the time and frequency extent of a signal, and the Time-Bandwidth Product of xn is 4. Based on Nyquist Sampling Theorem, when we sample a Continuous-Time signal, the sampling frequency is no less than 2 times b

3、andwidth of the Continuous-Time signal. But in practical engineering, the sampling frequency is no less than 35 times bandwidth of the Continuous-Time signal. Why?Answer: 5. Write 3 types of the representation of a signal x(t), and explain their physical meanings:(1) (2) (3) 二、 選擇題（4分/每題，共20分）1. Det

4、ermine the output of the systems described by following differential equation: ，Determine zero-initial response and zero-state response ：（ ）（A）,，Example 3.18.(a) Rectangular pulse in the time domain. (b) DTFT in the frequency domain.（B）,（C）,（D）,2. Evaluate the following discrete-time convolution sum

5、s: = ( )(A) (B) (C) (D) 3. ，determine=( )。(A) (B) (C) (D) 4. The transfer function of a LTI system is, the system belongs to( ) type . （A）high-pass (B) low-pass (C) band-pass (D) band-stop5. The impulse response of a LTI system is ,the step response for the system is ( ).(A) (B), here (C) (D) , here

6、 三、 計算題（共60分）1. （10 scores）A signal is shown below: 1）Determine the Fourier Transform for the signals ;2) sketch 2. （10 scores）An interconnection of LTI systemsis depicted in following figure. if 1）Determine the impulse response of the overall system, and sketch ;2）Is this system a) stable? b) causa

7、l?;3. （12 scores）A LTI discrete-time system is show as following,1）Find difference-equation descriptions for the system;2）Determine the impulse response ;3）If, determine the output ;4. （13 scores） Consider the system depicted in (a) below. The FT of the input signal is depicted in (b).Let and .Sketch and for the following cases: and .5. （15 scores） A discrete-time system for processing continuous-time signals is shown below. 1)Find t