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WorksheetsDSP - Mock Test
Total questions: 58
Worksheet time: 29mins
Name
Class
Date
1.
If x(n) and X(k) are an N-point DFT pair, then X(k+N)=?
a)
X(-k)
b)
-X(k)
c)
X(k)
d)
None of the mentioned
2.
What is the DFT of the four point sequence x(n)={0,1,2,3}?
a)
{6,-2+2j-2,-2-2j}
b)
{6,-2-2j,2,-2+2j}
c)
{6,-2+2j,-2,-2-2j}
d)
{6,-2-2j,-2,-2+2j}
3.
Which of the following is true in case of Overlap add method?
a)
M zeros are appended at last of each data block
b)
M zeros are appended at first of each data block
c)
M-1 zeros are appended at last of each data block
d)
M-1 zeros are appended at first of each data block
4.
Which of the following statements is true?
a)
Only DFT is periodic and not inverse IDFT.
b)
Only IDFT is periodic and not inverse DFT.
c)
Both DFT and IDFT are periodic.
d)
Both DFT and IDFT are not periodic.
5.
Which of the following is an advantage of fixed-point arithmetic over floating-point arithmetic?
a)
Higher precision
b)
Faster computation speed
c)
Easier range scaling
d)
Better handling of overflow and underflow
6.
Which arithmetic operation can introduce quantization errors in fixed-point arithmetic?
a)
Addition
b)
Subtraction
c)
Multiplication
d)
Division
7.
Which representation uses a fixed binary point, where the bit to the right represents the fractional part of the number?
a)
Floating point representation
b)
Sign-magnitude representation
c)
Fixed point representation
d)
Two's complement representation
8.
The difference between an input value and its quantized value is called:
a)
Overflow error
b)
Round-off error
c)
Quantization error
d)
Coefficient error
9.
What is the general system function of an FIR system?
a)
∑M−1k=0bkx(n−k)
b)
∑Mk=0bkz−k
c)
∑M−1k=0bkz−k
d)
None of the mentioned
10.
The desired frequency response is specified at a set of equally spaced frequencies defined by the equation
a)
π2M(k+α)
b)
πM(k+α)
c)
2πM(k+α)
d)
None of the mentioned
11.
Direct form realization of FIR filters requires ___ registers
a)
2M
b)
M
c)
M-1
d)
M+1
12.
The values of cutoff frequencies in general depend on which of the following?
a)
Type of the window
b)
Length of the window
c)
Type & Length of the window
d)
None of the mentioned
13.
Which of the following is the first method proposed for design of FIR filters?
a)
Chebyshev approximation
b)
Frequency sampling method
c)
Windowing technique
d)
None of the mentioned
14.
Which blocks are not considered the basic building blocks for filter structures?
a)
Adder
b)
Subtractor
c)
Multiplier
d)
Delay
15.
The different structures for representing FIR Filters are
(i)Cascade Form
(ii)Transposed Form
(iii)Direct Form
(iv)Parallel Form
a)
(i), (ii) and (iii)
b)
(iii)
c)
(i) and (iii)
d)
(i) and (iv)
16.
What is the order of operations to be performed in order to realize linear phase IIR filter?
(i) Passing x(-n) through a digital filter H(z)
(ii) Time reversing the output of H(z)
(iii) Time reversal of the input signal x(n)
(iv) Passing the result through H(z)
a)
(i),(ii),(iii),(iv)
b)
(iii),(i),(ii),(iv)
c)
(ii),(iii),(iv),(i)
d)
(i),(iii),(iv),(ii)
17.
Which of the following filter transformations are not possible?
a)
High pass analog filter to low pass digital filter
b)
High pass analog filter to high pass digital filter
c)
Low pass analog filter to low pass digital filter
d)
None of the mentioned
18.
What is the equation for normalized frequency?
a)
F/Fs
b)
F.Fs
c)
Fs/F
d)
None of the mentioned
19.
Which of the following is the correct relation between ω and Ω?
a)
Ω=ωT
b)
T=Ωω
c)
ω=ΩT
d)
None of the mentioned
20.
The magnitude response of an anti-symmetric FIR filter is ______ around the frequency axis.
a)
Symmetric
b)
Anti-symmetric
c)
Constant
d)
Random
21.
Symmetric FIR filters have an all-zero frequency response at the ______ frequency.
a)
Nyquist
b)
Half the sampling rate
c)
Zero
d)
DC
22.
According to Goertzel Algorithm, if the computation of DFT is expressed as a linear filtering operation, then which of the following is true?
a)
yk(n)=∑Nm=0x(m)W−k(n−m)N
b)
yk(n)=∑N+1m=0x(m)W−k(n−m)N
c)
yk(n)=∑N−1m=0x(m)W−k(n+m)N
d)
yk(n)=∑N−1m=0x(m)W−k(n−m)N
23.
If yk(n) is the convolution of the finite duration input sequence x(n) of length N, then what is the impulse response of the filter?
a)
WN-kn
b)
WN-kn u(n)
c)
WNkn u(n)
d)
None of the mentioned
24.
What is the system function of the filter with impulse response hk(n)?
a)
11−W−kNz−1
b)
11+W−kNz−1
c)
11−WkNz−1
d)
11+WkNz−1
25.
What is the expression to compute yk(n) recursively?
a)
yk(n)=WN-k yk(n+1)+x(n)
b)
yk(n)=WN-k yk(n-1)+x(n)
c)
yk(n)=WNk yk(n+1)+x(n)
d)
None of the mentioned
26.
If x1(n) and x2(n) are two real valued sequences of length N, and let x(n) be a complex valued sequence defined as x(n)=x1(n)+jx2(n), 0≤n≤N-1, then what is the value of x1(n)?
a)
x(n)−x∗(n)2
b)
x(n)+x∗(n)2
c)
x(n)−x∗(n)2j
d)
x(n)+x∗(n)2j
27.
Which of the following is true regarding the number of computations required to compute an N-point DFT?
a)
N^2 complex multiplications and N(N-1) complex additions
b)
N^2 complex additions and N(N-1) complex multiplication
c)
N^2 complex multiplications and N(N+1) complex addition
d)
N^2 complex additions and N(N+1) complex multiplications
28.
Which of the following is true regarding the number of computations required to compute DFT at any one value of ‘k’?
a)
4N-2 real multiplications and 4N real additions
b)
4N real multiplications and 4N-4 real additions
c)
4N-2 real multiplications and 4N+2 real additions
d)
4N real multiplications and 4N-2 real additions
29.
WN^k+N/2=?
a)
WN^k
b)
-WN^k
c)
WN^-k
d)
None of the mentioned
30.
What is the real part of the N point DFT XR(k) of a complex valued sequence x(n)?
a)
∑N−1n=0[xR(n)cos2πknN–xI(n)sin2πknN]
b)
∑N−1n=0[xR(n)sin2πknN+xI(n)cos2πknN]
c)
∑N−1n=0[xR(n)cos2πknN+xI(n)sin2πknN]
d)
None of the mentioned
31.
Consider a 4-point DIF FFT with the input sequence [1, 0, 1, 0]. Calculate the output sequence.
a)
[1, 0, 1, 0]
b)
[1, 1, 0, 0]
c)
[2, 0, 0, 0]
d)
[0, 0, 1, 1]
32.
For an 8-point DIF FFT, if the output at stage 1 is [2, -1, 4, 3, 0, 0, 0, 0], what is the output sequence at the final stage?
a)
[2, -1, 4, 3, 0, 0, 0, 0]
b)
[4, -2, 8, 6, 0, 0, 0, 0]
c)
[2, -1, 4, 3, 2, -1, 4, 3]
d)
[4, -2, 4, 3, 0, 0, 0, 0]
33.
Given a 4-point DIF FFT with the input sequence [1, 1, 1, 0], calculate the output sequence.
a)
[3, 1 - i, -1, 1 + i]
b)
[2, 1 - i, 0, 1 + i]
c)
[1, 2, 3, 4]
d)
[1, -1, 1, -1]
34.
Find 8-point IDFT of a sequence X[k]={4, 1-j2.414, 0, 1-j0.414, 0} using DIF FFT algorithm.
a)
{1,1,1,1,0,0,0,0}
b)
{8,8,8,8,0,0,0,0}
c)
{8,8,8,8,-8,-8,-8,-8}
d)
{1,1,1,1,-1,-1,-1,-1}
35.
Consider a 4-point DIF IFFT with the input sequence [3, 2, 1, 0]. Calculate the output sequence.
a)
[1, 2, 3, 0]
b)
[0, 1, 2, 3]
c)
[3, 2, 1, 0]
d)
[0, 3, 2, 1]
36.
For an 8-point DIF IFFT, if the output at stage 1 is [2, -1+j, 3, 1-j, 0, 0, 0, 0], what is the output sequence at the final stage?
a)
[2, -1+j, 3, 1-j, 0, 0, 0, 0]
b)
[4, -2+2j, 6, -2j, 0, 0, 0, 0]
c)
[4, -1-j, 3, 1, 0, 0, 0, 0]
d)
[2, -2j, 3, -j, 0, 0, 0, 0]
37.
Given a 4-point DIF IFFT with the input sequence [1, j, 0, -j], calculate the output sequence.
a)
[0, 1, 0, 0]
b)
[0, 0, 1, 0]
c)
[0, 0, 0, 1]
d)
[1, 0, 0, 0]
38.
Find DFT of a sequence x(n)={1,3,2,2,1,3,2,2}using DIF FFT algorithm.
a)
{16, 0, -2+2j, 0, -4, 0, -2-2j, 0}
b)
{16, 0, 2-2j, 0, -4, 0, 2+2j, 0}
c)
{16, 0, 2+2j, 0, 4, 0, 2-2j, 0}
d)
{16, 0, -2-2j, 0, -4, 0, -2+2j, 0}
39.
Consider a 4-point DIF FFT with the input sequence [1, 2, 3, 4]. Calculate the output sequence.
a)
[10, -2-2j, -2, -2+2j]
b)
[10, -2+2j, -2, -2-2j]
c)
[1, 2, 3, 4]
d)
[1+2j, -1, 3, -1-2j]
40.
For an 8-point DIF FFT, if the output at stage 1 is [1, -2, 3, 4, 0, 0, 0, 0], what is the output sequence at the final stage?
a)
[1, -2, 3, 4, 0, 0, 0, 0]
b)
[2, -4, 6, 8, 0, 0, 0, 0]
c)
[1, -2, 3, 4, 1, -2, 3, 4]
d)
[2, -2, 3, 4, 0, 0, 0, 0]
41.
Consider a 4-point DIF FFT with the input sequence [1, 1, -1, 0]. Calculate the output sequence.
a)
[1, 2j, -2, -2j]
b)
[1, 1+1j, -2, 1-1j]
c)
[1, -1+1j, -2, 1-1j]
d)
[1, 1+1j, -2, -2j]
42.
Which of the following is not an advantage of digital image processing?
a)
Flexibility
b)
Higher Bandwidth
c)
Accuracy
d)
Easy Storage
43.
What is zero padding technique?
a)
Zeroes are added at the end of the sequence to make the number of samples equal to a power of two.
b)
Zeroes are added at the start of the sequence to make the number of samples equal to a power of two.
c)
Zeroes are added anywhere in between the sequence to make the number of samples equal to a power of two.
d)
None of the mentioned.
44.
Which of the following statements is invalid about linear convolution?
a)
It needs zero padding.
b)
The sequence length of input and output is the same.
c)
The input and output sequence is aperiodic.
d)
All the above statements are valid.
45.
In the Overlap add method to compute N point DFT, M-1 zeroes are added
a)
At the first of each data block
b)
At the last of each data block
c)
In between the data block
d)
No zeroes are added
46.
The IDFT is given by:
a)
X[k] = Σ(x[n] * exp(2πi * k * n / N))
b)
X[k] = Σ(x[n] * exp(-2πi * k * n / N))
c)
x[n] = Σ(X[k] * exp(2πi * k * n / N))
d)
x[n] = Σ(X[k] * exp(-2πi * k * n / N))
47.
Which of the following is the disadvantage of Hanning window over rectangularwindow?
a)
More side lobes
b)
Less side lobes
c)
More width of main lobe
d)
None of the mentioned
48.
If X(k) discrete Fourier transform of x(n), then the inverse discrete Fourier transform of X(k) is?
a)
1N∑N−1k=0X(k)e−j2πkn/N
b)
∑N−1k=0X(k)e−j2πkn/N
c)
∑N−1k=0X(k)ej2πkn/N
d)
1N∑N−1k=0X(k)ej2πkn/N
49.
The Nth root of unity WN is given as
a)
e^j2πN
b)
e^-j2πN
c)
e^-j2π/N
d)
e^j2π/N
50.
What is the value of x(n)*h(n), 0≤n≤11 for the sequences x(n)={1,2,0,-3,4,2,-1,1,-2,3,2,1,-3} and h(n)={1,1,1} if we perform using overlap add fast convolution technique?
a)
{1,3,3,1,1,3,5,2,2,2,3,6}
b)
{1,2,0,-3,4,2,-1,1,-2,3,2,1,-3}
c)
{1,2,0,3,4,2,1,1,2,3,2,1,3}
d)
{1,3,3,-1,1,3,5,2,-2,2,3,6}
51.
Find the dft of the sequence[1,3,1,0]
a)
[3, 2-3i, -3, 2+3i]
b)
[2-3i, 3, 2+3i, 3]
c)
[3-2i, 3, 3+2i, 3]
d)
[3, 2+3i, -3, 3-2i]
52.
The scaling of a sequence x[n] by a factor α is given by
a)
y[n] = α [x[n]]2
b)
y[n] = α x[n2]
c)
y[n] = α x[n]
d)
y[n] = x[n]x[-n]
53.
In Overlap save method of long sequence filtering, what is the length of the input sequence block?
a)
L+M+1
b)
L+M
c)
L+M-1
d)
None of the mentioned
54.
If the x(n) is real, then which of these relations would be true?
a)
X(ω)=X(-ω)
b)
X(ω)=-X(-ω)
c)
X*(ω)=X(ω)
d)
X*(ω)=X(-ω)
55.
An anti-imaging filter is used
a)
after down sampling
b)
after up sampling
c)
before up sampling
d)
before down sampling
56.
In interpolation, the sampling rate
a)
remains constant
b)
reduces from Fs to Fs/L
c)
increases from Fs to LFs
d)
doubles
57.
Why is frequency warping done in digital filter design?
a)
To adjust the phase response of the filter
b)
To modify the sampling rate of the filter
c)
To correct for frequency distortion caused by the sampling process
d)
To increase the order of the filter
58.
The magnitude response of an IIR filter can be visualized using a:
a)
Pole-zero plot
b)
Phase response plot
c)
Frequency response plot
d)
Impulse response plot
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