UNIVERSITY OF MINES AND TECHNOLOGY, TARKWA

FIRST SEMESTER EXAMINATIONS, April 2024

COURSE NO: CE/EL 463
COURSE NAME: Digital Signal and Image Processing
INSTRUCTIONS
CLASS: CE/EL TIME: 3 Hours

Name: __________________________________________ Index Number: _______________

INSTRUCTION: Answer All Questions on this Paper in the Answer Booklet.

c. Digital
1. The function y[n] = sin4πn is d. Continuous
periodic. 6. The phenomenon called ……….
a. True occurs if the sampling frequency is
b. False less than the Nyquist rate.
a. Aliasing
2. What is the nature of the following
b. Shrinking
function: y[n] = y[n-1] + x[n]? c. Shannon
a. Integrator d. Delay
b. Differentiator 7. A linear system is said to obey the
c. Subtractor rules of
d. Accumulator a. Scaling
3. The system defined by the function b. Additivity
y[n] = x[n-1] – x[n-4] is memoryless c. both scaling and additivity
a. True d. homogeneity
b. False 8. Convolve x[n] = {1,3,3,1} and h[n]
= {1,2,1} thus y[n] = h[n]*x[n]
4. The type of systems characterized by a. y[n] = h[n]*x[n] =
input and the output quantized at {1,5,10,10,5,1}
certain levels are called b. y[n] = h[n]*x[n] =
a. Analog {1,5,0,10,5,1}
b. Discrete c. y[n] = h[n]*x[n] =
c. Continuous {1,5,6,10,5,1}
d. Digital d. y[n] = h[n]*x[n] =
5. The type of systems which are {1,5,10,100,5,1}
characterized by input and output Use this preamble to answer questions 9 to
capable of taking any value in a 12.
particular set of values is called
a. Analog Consider the analog signal 𝑋𝑎 (𝑡) =
b. Discrete 3 cos 100𝜋𝑡

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9. Determine the minimum sampling b. Electronic attenuator
rate required to avoid aliasing c. Both amplifier and
a. 50Hz attenuator
b. 100Hz d. Adder
c. 150Hz 16. Resistor performs amplitude scaling
d. 200Hz when x (t) is voltage, a is resistance
10. If the signal is sampled at Fs = and y (t) is output current.
200Hz, what discrete-time signal a. True
will be obtained after sampling? b. False
a. 𝟑 𝒄𝒐𝒔 𝒏
л
17. Which of the following is an
𝟐
л example of physical device which
b. 3 𝑐𝑜𝑠 3 𝑛
adds the signals?
3л
c. 3 𝑐𝑜𝑠 𝑛 a. Radio
2
л b. Audio mixer
d. 3 𝑐𝑜𝑠 5 𝑛
c. Frequency divider
11. If the signal is sampled at Fs = 75Hz, d. Subtractor
what discrete-time signal will be 18. A time-invariant system is a system
obtained after sampling?
𝟐л whose output
a. 3cos n a. increases with a delay in
𝟑
л
b. 3cos3 n input
6л b. decreases with a delay in
c. 3cos 3 n input
4л
d. 3cos 3 n c. remains the same with a
delay in input
12. What is the frequency 0<F<Fs/2 of a
d. vanishes with a delay in input
sinusoid that yields samples identical
to those obtained in question 9? 19. The system y(n) = x(n) + 2x(n + 3) is
a. 25Hz a. causal system
b. 50Hz b. non-causal system
c. 100Hz c. partly (a) and partly (b)
d. 75Hz d. none of these
20. All real-time systems concerned with
the concept of causality are
13. This signal is casal 𝑥(𝑛) = a. non-causal
𝑒 2𝑛 𝑢(𝑛 − 1) b. causal
c. neither causal nor non-causal
a. True d. memoryless
b. False 21. Should real-time instruments like
14. All causal systems must have the oscilloscopes be time-invariant?
component of a. Yes
a. Memory b. Sometimes
b. time invariance c. Never
c. stability d. They have no relation with
d. linearity the time variance
15. Which of the following is an 22. The ROC in z-transform indicated as
example of amplitude scaling? ___________
a. Electronic amplifier a. Square

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 b. Rectangle 𝒀(𝒛) 𝟏 + 𝟎.𝟖𝒛−𝟏
a. 𝐇(𝒛) = 𝑿(𝒛) = 𝟏 − 𝟎.𝟐𝒛−𝟏
c. Circle
d. None of the above 𝑌(𝑧) 1 + 0.9𝑧 −1
b. H(𝑧) = 𝑋(𝑧) = 1 − 0.2𝑧 −1
23. An LTI system acts as a _______
𝑌(𝑧) 1 + 0.2𝑧 −1
a. Filter c. H(𝑧) = 𝑋(𝑧) = 1 − 0.2𝑧 −1
b. Comparator 𝑌(𝑧) 1 + 0.8𝑧 −1
c. Integrator d. H(𝑧) = 𝑋(𝑧) = 1 − 0.7𝑧 −1
d. None of the above 30. Which of the following is/are
24. Non-periodic and deterministic common applications of IIR filters?
signals are energy signals whereas
a. Audio equalisation
periodic and random signals are
power signals. b. IoT/IIoT smart sensors
a. true c. High-speed RF applications
b. false d. All of the above
25. Y (n) = x (2n) is ________ 31. The product of two odd signals is:
a. Compressed signal
b. Expanded signal a. Odd
c. Shifted signal b. Even
d. Amplitude scaled signal by a c. Both (a) and (b)
factor of 2 d. Zero
26. Y (n) = x (n/5) is _______
32. Which of the following is not a type
a. Compressed signal
b. Expanded signal of discrete system?
c. Time-shifted signal a. Recursive systems
d. Amplitude scaled signal by b. Dynamic systems
factor 1/5 c. Non-causal systems
27. In discrete signal, if y [n] = x [k*n] d. Non-dynamic systems
and k>1 then ______ 33. The advantages of discrete signal
a. Some samples are lost from
processing is/are:
x [n]
b. Some samples are added to x a. Cost effective.
[n] b. Time-sharing
c. It does not affect samples c. High flexibility
d. Samples will be increased d. All of the above
with factor k 34. Which of the following is a
28. Amplifiers, motors, filters etc. are
characteristic of the power signal?
examples of which system type?
a. Distributed parameter a. Power signal is infinite.
systems b. Power signals are time limited.
b. Unstable systems c. Aperiodic signals are power
c. Discrete-time systems signals.
d. Continuous-time systems d. None of the above
29. Find the transfer function described 35. The Digital Signal Processing
by the difference equation: y[n] – system:
0.2y[n-1] = x[n] + 0.8x[n-1]
a. Consumers more power.

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 b. Consumes less power. b. y[n] + 0.5y[n-2] = 0.8x[n] +
c. Applicable for low-frequency 0.1x[n-1] - 0.3x[n-2]
signals. c. y[n] + 0.8y[n-2] = 0.8x[n] +
d. Both (a) and (c). 0.1x[n-1] - 0.3x[n-2]
36. The length of the output sequence (n) d. y[n] + 0.3y[n-2] = 0.8x[n] +
of the two sequences (n1 and n2) can 0.1x[n-1] - 0.3x[n-2]
be calculated using the formula:
a. n = n1 - n2 + 1
b. n = n1 + n2 - 1
c. n = n1 - n2 - 1
d. n = n1 + n2 + 1
37. One-sided Z-transform is also known
as:
a. Unilateral Z-transform
b. Bilateral Z-transform 41. The addition of zeroes at the end of
c. Trilateral Z-transform the sequence when it is represented
d. None of the above as the power of integer is refer as:
a. Region of Convergence
38. An analog signal has a bandwidth of
b. Bilateral transform
5KHz. If we are using an N-point
c. Zero padding
DFT to compute the signal spectrum
d. None of the above
with a resolution less than or equal to
42. The z-transform and the poles of the
25Hz. Find the minimum length of
the signal. system h(n) = 3^n u(n) is:
a. 0.2s a. 3z/z – 3 and 3
b. 0.04s b. 3z / z + 3 and -3
c. 0.02s c. z / z + 3 and -3
d. 0s d. z / z – 3 and 3
43. The system that accepts the input in
39. The transfer function of the Z-
transform of the function y(n) = x(n) the discrete form and produces the
+ y(n - 1) is: discrete time output is known as:
a. z/ z + 1 a. Linear system
b. z/ 2z b. Discrete time system
c. z/ z - 1 c. LTI system
d. z - 1/z d. All of the above
40. The Difference Equation for the 44. The algorithm used for the
direct form I recursive filter shown computation of DFT based on the
below is: decomposition of N-point DFT is
a. y[n] + 0.3y[n-2] = 0.8x[n] + known as:
0.1x[n-1] - 0.3x[n-2] a. Overlap save
b. Phase algorithm

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 c. Divide and Conquer b. Impulse
d. Both (a) and (b) c. Exponential
45. Using the FFT expression d. All of the above
N/2(log2N), determine the number 51. Which technique is used to obtain a
of complex multiplications for the 8- discrete-time signal from a
point Radix-2 FET. continuous-time signal?
a. 32 a. Differentiating
b. 12 b. Convolution
c. 80 c. Integrating
d. 4 d. Sampling
46. The advantages of the butterfly 52. What should be the minimum
structure is: frequency of sampling to avoid
a. Reduces computation aliasing?
complexity. a. F/2 (here, F is the analogue
b. Requires a fewer number of signal frequency)
multiplications and additions. b. F
c. Combines the result of small c. 2F
DFTs into larger DFTs. d. 4F
d. All of the above 53. Which of the following factors
47. Digital filters are: provides the quality of output from
a. Highly expensive. the A/D converter?
b. Consumer very less power. a. Quantisation to signal noise
c. Programmable ratio
d. Cannot handle low-frequency b. Signal to quantisation noise ratio
signals. c. Quantisation error
48. The window technique whose main d. None of the above
lobe width is 12pi/N is called: 54. In RADAR signal application, which
a. Hamming window of the following elements is
b. Blackmann window unnecessary?
c. Kaiser window a. Digital signal processor
d. Rectangular window. b. A/D converter
49. Which type of filters are all pole c. D/A converter
filters? d. All of the above
a. Type-I Chebyshev filters 55. In which condition of ROC is a
b. Type-II Chebyshev filters linear time-invariant system called
c. Both (a) and (b) BIBO stable?
d. None of the above a. The ROC of the system is a unit
50. Which of the following is/are circle
standard test signals? b. The ROC of the system
a. Step includes unit circle

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 c. The ROC of the system excludes 61. If discrete-time signal passes
unit circle through an analog to digital
d. None of the above converter we get ______
56. Which of the following system a. Binary sequence
functions represents an all pass b. Decimal sequence
filter? c. Hexadecimal sequence
a. A. H(z)=zk d. None of the above
b. B. H(z)=z-k 62. The signal processing is performed
c. C. H(z)=z1/k to ____________ the signal
d. D. H(z)=z2k a. Analyze
57. In which of the following b. Modify
applications digital signal processing c. Synthesize
is used? d. All the above
a. Space applications 63. How many types of signal
b. Biomedical applications processing are there?
c. Video processing a. One
d. All of the above b. Two
58. Which of the following is/are c. Three
common applications of IIR filters? d. Four
e. Audio equalisation 64. The digital signal processing can be
f. IoT/IIoT smart sensors used in _______
g. High-speed RF applications a. Speech and audio processing
h. All of the above b. Image and video processing
59. The circular convolution of both of c. Military and space applications
these sequences X1(n)={2,1,2,1} and d. All the above
x2(n)={1,2,3,4} would be: 65. The disadvantages of FIR filter are
a. {14,16,14,16} _________
b. {2,3,6,4} a. Complex
c. {16,16,14,14} b. Requires more filter coefficient
d. {14,14,16,16} c. Simple
60. The number of complex additions d. Both a and b
that we need to perform in the linear 66. The scaling operation also called as
filtering of any sequence using the __________
FFT algorithm would be: a. Up-sampling
a. Nlog₂N b. Down-sampling
b. (N/2)log₂N c. Both a and b
c. 2Nlog₂N d. None of the above
d. (N/2)logN 67. ____ parameters are required to
calculate correlation between X(n)
and Y(n) signals?

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 a. Noise signal b. poles & zeros, Zeros
b. Time delay c. Zeros, zeros
c. Attenuation factor d. none of above
d. All of the above 74. A factor-of-2 sampling rate
68. One application of convolution is expansion leads to a compression of
a. Sampling by a factor of 2 and a 2-fold
b. Quantization repetition in the baseband [0, 2 ].
c. Aliasing This process is called………
d. Filtering a. imaging
69. The circular convolution of a signal b. sampling
x1[ n] x [ n] c. decimation
of length L and 2 of
d. none of above
length P , where L  P results in a
75. Which of the Following is not a
x [ n]
signal 3 of length Filter?
a. L a. Graphic Equalizer on a stereo
b. L+P-1 system
c. P b. Tone control on a stereo system
d. P+L+1 c. Ear
70. The twiddle factor, WN = e–j2 /N, d. all of above
N /2
76. Finite Impulse Response (FIR) is a
evaluate WN has a value of ….
a. feedforward filter
a. 1
b. feedback filter
b. -1
c. a & b
c. 0
d. all of above
d. ∞
77. At what points, a continuous image
71. Identify the speediest image
is digitized?
processing approach?
a. Sampling
a. Analog
b. Vertex
b. Digital
c. Contour
c. Photographic
d. Random
d. Optical
78. _________ are the main elements of
72. Determine the convolution sum of
digital signal processing system
two sequences x(n) = {3, 2, 1, 2} and
a. Quantizer, Sampler
h(n) = {1, 2, 1, 2}
b. Digital signal processor
a. y(n) = {3,8,8,12,9,4,4}
c. Decoder
b. y(n) = {3,8,3,12,9,4,4}
d. All of the above
c. y(n) = {3,8,8,12,9,1,4}
79. The speech signals are _______
d. y(n) = {3,8,8,1,9,4,4}
a. One dimensional
73. FIR filters have ……., and IIR filters
b. Two dimensional
have ……….
c. Three dimensional
a. Zeros, poles & zeros

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 d. Multidimensional b. Shading Correction
80. Which of the following correctly c. Pixelation
describes the slightest visible change d. Region of Interest Operations
in the level of intensity? 86. Which of the following is the
a. Contour disadvantage of a smoothing filter?
b. Saturation a. Blur inner pixels
c. Contrast b. Blur edges
d. Intensity Resolution c. Sharp edges
81. What is the name of the tool that d. Remove sharp transitions
helps in zooming, shrinking, 87. Which of the following is used to
rotating, etc.? resolve the dark features in the
a. Filters image?
b. Interpolation a. Gaussian Transform
c. Sampling b. Laplacian Transform
d. None of the above c. Power-law Transformation
82. The dynamic range of the imaging d. Histogram Specification
system is a quantitative relation 88. What is defined by the total number
where the upper limit can be of pixels within the region?
determined by a. Area
a. Brightness b. Brightness
b. Contrast c. Intensity
c. Saturation d. Perimeter
d. Noise 89. _________ is the principal factor,
83. The lower limit of the dynamic range which helps in determining an
ratio can be determined by image's spatial resolution.
a. Brightness a. Dynamic range
b. Contrast b. Quantization
c. Saturation c. Sampling
d. Noise d. Contrast
84. Which of the following is the most 90. If the pixel value is ‘0’ then it
famous single sensor for image represents ___ color?
acquisition? a. White
a. Photodiode b. Black
b. CMOS c. Red
c. Microdensitometer d. Grey
d. None of the above 91. If the pixel value is ‘1’ then it
85. Which of the following is not a represents ___ color?
correct example of Image a. White
Multiplication? b. Black
a. Masking c. Red

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 d. Yellow b. Assist in improving images for
92. Grey color of image lies between human interpretation
____ colors? c. Retrieved easily
a. White and black d. All the above
b. White and red 97. Which of the following is the
c. Black and red software used in digital image
d. Black and green processing?
93. A color image is also called ____? a. Adobe Photoshop
a. RGB image b. Mathlab
b. Grey scale image c. Open CV
c. Monochrome images d. All the above
d. Both b and c 98. A RGB images comprises of _____
94. Which of the following are the basic number of bits/pixels for 8-bit
functions of digital image monochrome?
processing? a. 24
a. Image enhancement b. 16
b. Noise addition c. 12
c. Distortion d. 8
d. All the above 99. In aliasing effect, on lowering high
95. Image enhancement technique frequency image component ____
benefit in terms of _____? the quality of image?
a. Visualization
a. Blurs
b. Removes noise
b. Clears
c. Clears image by debluring
c. Both a and b
d. All the above
d. None of the above
96. Which of the following are the
100. Which of the following is the
advantages of digital image
first step in image processing?
processing?
a. Segmentation
a. Available in multiple formats (X-
b. Image acquisition
Ray, image)
c. Image restoration
d. Image enhancement

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