大学MOOC Digital Signal Processing(Nanjing University of Posts and Telecommunications)1458192173 最新慕课完整章节测试答案

Circular Shift and Circular Convolution

1、判断题：

‌Consider two length-N sequences, both defined for  , perform N-point circular convolution on them, the resulting sequence still falls on

‍

‌

‍选项：
A: 正确
B: 错误
答案: 【 正确】

Linear Convolution Periodic Convolution Circular Convolution

1、单选题：
‎Consider the linear convolution of two 4-points sequences is {-6, 3, 12, 7, 6, -1, 5},  their 4-point circular convolution is ：‏
选项：
A:
B:
C:
D:
答案: 【 】

Unit Test for Unit 8

1、单选题：
‍The Discrete Fourier Transform is an equal-interval sampling of the z-transform on‏
选项：
A: unit circle
B: real axis
C: imaginary axis
D:
答案: 【 unit circle】

2、单选题：

‌The spectrum of a sequence is , then X[3] in the 6-point DFT of this sequence is equal to

‏选项：
A: 2/3
B: 1/3
C: 3/2
D: 3
答案: 【 2/3】

3、单选题：

‌Let the N-point DFT of the sequence x[n] be X[k], then the digital frequency  corresponding to the frequency number k is equal to

​选项：
A:
B:
C:
D:
答案: 【 】

4、单选题：
‏Let the 6-point DFT of the real sequence x[n] be X[k], X[0]=2，X[1]=1.5-0.866j, X[2]=0.5-0.866j, X[3]=0, then according to the symmetry, we can get X[4]=       , X[5]=       .‍
选项：
A: 0.5+0.866j,  1.5-0.866j
B: 0.5+0.866j,  1.5+0.866j
C: 1.5+0.866j,  0.5+0.866j
D: 0,  0.5+0.866j
答案: 【 0.5+0.866j,  1.5+0.866j】

5、单选题：

‏Consider two finite-length sequences and if you use circular convolution to calculate their linear convolution, then the circle convolution should take at least      points.

‎选项：
A: 60
B: 24
C: 38
D: 61
答案: 【 61】

6、判断题：
‏For a length-M sequence, N-point sampling within one cycle of the spectrum causes the time-domain sequence to extend with N as the cycle. The condition for undistorted sampling in the frequency domain is that M is greater than or equal to N.​
选项：
A: 正确
B: 错误
答案: 【 错误】

7、判断题：
‌If the real sequence x[n] is an even-symmetric sequence, then X[k] is an imaginary sequence and is even-symmetric.​
选项：
A: 正确
B: 错误
答案: 【 错误】

8、判断题：
‎When using DFT for spectrum analysis, if you want to improve the frequency resolution, you can fill the time sequence with zeros, thereby increasing the number of  DFT points and achieving the purpose of distinguishing similar frequency components.​
选项：
A: 正确
B: 错误
答案: 【 错误】

9、判断题：
‏The DFT pair can be formed by taking the principal-value sequence of the time domain and frequency domain of  DFS respectively.​
选项：
A: 正确
B: 错误
答案: 【 正确】

10、判断题：

‍Let x[n] be a real length-N sequence, and its N-point DFT is X[k], then 

‎选项：
A: 正确
B: 错误
答案: 【 正确】

Application and Algorithms of FFT

1、单选题：
‎The number of complex multiplication and complex addition for direct calculation of 8-point DFT are respectively (  ) and (  )‎
选项：
A: 32   28
B: 64   56
C: 28   32
D: 56   64
答案: 【 64   56】

Decimation in Frequency Radix-2 FFT (DIF) Algorithm

1、单选题：
‎In 4-point DIF FFT, how many butterfly graph will appear when a 4-point DFT is decomposed into 2-point DFT?​
选项：
A: 1
B: 2
C: 3
D: 5
答案: 【 2】

Decimation in Time Radix-2 FFT (DIT) Algorithm

1、单选题：
‍(  )-point radix-2 DIT FFT can be used on one input sequence with length of 9.‏
选项：
A: 2
B: 4
C: 8
D: 16
答案: 【 16】

IDFT Calculation with FFT

1、判断题：
‍Use FFT to get IDFT, the result is time domain sequence rather than frequency domain sequence.‏
选项：
A: 正确
B: 错误
答案: 【 正确】

Linear Convolution with FFT

1、单选题：
‎(   )-point radix-2 FFT can realize the fast convolution of 11-point and 18-point sequence.‎
选项：
A: 11
B: 18
C: 28
D: 32
答案: 【 32】

Unit Test for Unit 9

1、单选题：
‍The number of complex multiplication and complex addition in a butterfly operation is (   ) and (   ) respectively.​
选项：
A: 1   1
B: 1   2
C: 2   1
D: 2   2
答案: 【 1   2】

2、单选题：
​The number of butterfly operation in 8-point DIF FFT flow graph is‍
选项：
A: 8
B: 12
C: 16
D: 20
答案: 【 12】

3、单选题：
‎The length of two time-domain sequences are both 50, If you want to calculate the linear convolution of two sequences with the fast convolution with radix-2, how many points should be selected for the fast convolution?‍
选项：
A: 50
B: 64
C: 101
D: 128
答案: 【 128】

4、单选题：
‌Which equation below is right to use DFT to calculate IDFT?‎
选项：
A:
B:
C:
D:
答案: 【 】

5、单选题：
‌A 512-point DFT of a length-478 sequence is to be computed. The number of complex multiplications needed for the direct evaluation of all DFT samples and FFT calculation are (    ).‍
选项：
A:
B:
C:
D:
答案: 【 】

6、判断题：
‍The N-point DFT of time domain sequence x[n] is {X[0],X[1],……X[N-1]},then its N-point FFT has the same result.‍
选项：
A: 正确
B: 错误
答案: 【 正确】

Analog Prototype Lowpass Filter Design

1、判断题：
‏The amplitude-frequency characteristics of Butterworth analog low-pass filters decrease monotonically with increasing frequency.‎
选项：
A: 正确
B: 错误
答案: 【 正确】

Bilinear Transformation Method

1、单选题：

‌The bilinear transformation  maps the left-half s-plane onto _____ of the z-plane, and the imaginary axis of the s-plane onto _______ of the z-plane.

‎选项：
A: outside the unit circle, the unit circle
B: inside the unit circle, the unit circle
C: upper half plane, upper half unit circle
D: left half plane，lower half unit circle
答案: 【 inside the unit circle, the unit circle】

Impulse Invariance Method

1、判断题：
‍The impulse invariance method is only suitable for designing band-limited filters due to the frequency aliasing effect.  ‌
选项：
A: 正确
B: 错误
答案: 【 正确】

LP AF to LP DF and HP DF

1、判断题：

‏The bilinear transformation that directly maps the analog low-pass filter to a digital high-pass filter is  .

​选项：
A: 正确
B: 错误
答案: 【 正确】

Preliminary Considerations

1、判断题：
‍h[n] corresponding to each of the four ideal filters is non-causal and of infinite length.‍
选项：
A: 正确
B: 错误
答案: 【 正确】

Unit Test for Unit 10

1、单选题：
‍Use analog filters to design IIR digital filters. If the designed analog filters are causally stable, which of the following characteristics of the s-plane to z-plane transformation ensures that the digital filters are also causally stable.‏
选项：
A: A point on the imaginary axis in the s-plane is mapped onto a point on the unit circle in the z-plane
B: A point in the right-half s-plane is mapped onto a point outside the unit circle in the z-plane
C: A point in the left-half s-plane is mapped onto a point inside the unit circle in the z-plane
D: Any point in the s-plane is mapped onto a unique point in the z-plane, and vice versa
答案: 【 A point in the left-half s-plane is mapped onto a point inside the unit circle in the z-plane】

2、单选题：

‍Bilinear transformation  maps analog angular frequency ___ to digital angular frequency

​选项：
A:
B:
C:
D:
答案: 【 】

3、单选题：

‌To design a digital low-pass filter using the bilinear transformation method and analog low-pass filter, assuming that the cut-off frequency of the analog low-pass filter is and the bilinear transformation parameter is selected, the cut-off frequency of the resulting digital filter is (  ).

‍选项：
A:
B:
C:
D:
答案: 【 】

4、多选题：
‏Using analog filters to design IIR digital filters, which two basic requirements must the s-plane to z-plane transformation meet?‏
选项：
A: A point on the imaginary axis in the s-plane is mapped onto a point on the unit circle in the z-plane
B: A point in the left-half s-plane is mapped onto a point outside the unit circle in the z-plane
C: The imaginary axis in the s-plane be mapped onto a point inside the unit circle in the z-plane
D: A point in the left-half s-plane is mapped onto a point inside the unit circle in the z-plane
答案: 【 A point on the imaginary axis in the s-plane is mapped onto a point on the unit circle in the z-plane;
A point in the left-half s-plane is mapped onto a point inside the unit circle in the z-plane】

5、判断题：
‏Prewarping cannot eliminate the nonlinear distortion of all frequency points generated in the transformation when the IIR DF is designed with the bilinear transformation method.‏
选项：
A: 正确
B: 错误
答案: 【 正确】

6、判断题：
‌When the IIR DF is designed with the bilinear transformation method, if the designed analog filter has linear magnitude response characteristic, then the converted digital filter also has linear magnitude response characteristic.‎
选项：
A: 正确
B: 错误
答案: 【 错误】

7、判断题：
‍Both the impulse response invariant method and the bilinear transformation method can make the left-half s-plane be mapped into the unit circle of the z-plane.‍
选项：
A: 正确
B: 错误
答案: 【 正确】

8、判断题：
‍Bilinear transformation method establishes a linear relationship between analog angular frequency and digital angular frequency.‍
选项：
A: 正确
B: 错误
答案: 【 错误】

9、判断题：
‎The impulse response invariant method establishes a one-to-one mapping relationship between the s-plane and the z-plane.‏
选项：
A: 正确
B: 错误
答案: 【 错误】

Linear Phase FIR Digital Filters

1、多选题：
‍The possible number of zeros of a linear-phase FIR digital filter can be ‍
选项：
A: 1
B: 2
C: 4
D: 8
答案: 【 1;
2;
4;
8】

2、判断题：
‎Compared with IIR filters, FIR filters have the advantage that FIR filters are all linear-phase.​
选项：
A: 正确
B: 错误
答案: 【 错误】

3、判断题：
‏The impulse response of a linear-phase FIR digital filter follows the equation h[n]=h[N-n] or h[n]=-h[N-n] where N is the order of the filter.‌
选项：
A: 正确
B: 错误
答案: 【 正确】

Unit Test for Unit 11

1、单选题：
‏The bandstop filter can be implemented with a linear phase FIR digital filter of type‍
选项：
A: 1
B: 2
C: 3
D: 4
答案: 【 1】

2、单选题：
‍The first three samples of h[n] of a linear-phase FIR digital filter are 2, -1, 3. If it can be used to design a highpass filter, then the latter sa