Signals & Systems Questions and Answers – Basic Operations on Signals – 2

This set of Signals & Systems Interview Questions and Answers for freshers focuses on “Basic Operations on Signals – 2”.

1. Considering Figure 1, sketch y= 2* x (t).
Y (t) = 2*x (t) is an example for amplitude scaling
a) Basic Signal Operations performed on sketch y = 2 * x (t) - option a
b) Basic Signal Operations performed on sketch y = 2 * x (t) - option b
c) Basic Signal Operations performed on sketch y = 2 * x (t) - option c
d) Basic Signal Operations performed on sketch y = 2 * x (t) - option d
View Answer

Answer: a
Explanation: Y (t) = 2*x (t) is an example for amplitude scaling. Here amplitude is scaled by a factor 2.

2. Considering Figure 1, sketch y= -3* x (t).
sketch y= -3* x (t)
a)sketch y= -3* x (t) - option a
b)sketch y= -3* x (t) - option b
c)sketch y= -3* x (t) - option c
d)sketch y= -3* x (t) - option d
View Answer

Answer: a
Explanation: Y (t) = -3*x (t) is an example for amplitude scaling. Here amplitude is scaled by a factor -3.

3. In the following diagram, X [n] and y [n] are related by ______
X [n] & y [n] are related by Y [n] = 2*x [n] in the following diagram
a) Y [n] = 2*x [n]
b) Y [n] = -2*x [n]
c) Y [n] = x [2n]
d) Y [n] = x [-2n]
View Answer

Answer: a
Explanation: Y [n] = 2*x [n] is an example for amplitude scaling of discrete time signal. The given figure is an example for 2*x [n] hence Y [n] = 2*x [n] is correct.
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4. X [n] and y [n] is as shown below, the relationship between x [n] and y [n] is given by ______
The relationship between x [n] & y [n] is given by Y [n] = x [n]/3
a) X [n] = y [n]/3
b) X [n] = 3* y [n]
c) Y [n] = x [n]/3
d) Y [n] = 3*x [n]
View Answer

Answer: c
Explanation: The given y [n] is amplitude scaling of a discrete time signal by a factor 1/3.
Hence the amplitude is reduced by 1/3.

5. Considering figure 3 below, is the following figure true for y [n] = x [2n]?
Find the following figure for y [n] = x [2n]
X [2n] is an example of time scaling for discrete time signal x [k*n]
a) True
b) False
View Answer

Answer: a
Explanation: X [2n] is an example of time scaling. For discrete time signal x [k*n], k>1 the samples will be lost.
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6. Considering figure 3 below, is the following figure true for y [n] = x [n/2]?
Find the following figure for y [n] = x [2n]
X [n/2] is an example for time scaling by factor 1/2 & it will be a stretched signal
a) True
b) False
View Answer

Answer: b
Explanation: X [n/2] is an example for time scaling by factor ½ and it will be a stretched signal. The discrete time signal should extend from -10 to 10.

7. Consider figure 4, is the given y (t) an integration of x (t)?
Find the integral from the given diagram
a) Y (t) = ∫x (t).dt
b) Y (t) = ∫x2 (t).dt
c) Y (t) = 3* ∫x (t).dt
d) Y (t) = 3* ∫x2 (t).dt
View Answer

Answer: a
Explanation: The given y (t) is integral of x (t) and amplitude 3 remains constant for t>1.
It is because of the properties of integration.
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8. Consider figure 4, is the given y (t) a differentiation of x (t)?
Find the differentiation from the given diagram
a) Y (t) = \(\frac{dx(t)}{dt}\)
b) Y (t) = \(\frac{-2dx(t)}{dt}\)
c) Y (t) = \(\frac{dx(-t)}{dt}\)
d) Y (t) = ∫x (t).dt
View Answer

Answer: a
Explanation: The given y (t) is differentiation of x (t) and hence we have impulses at -1, 0 and 1.

9. The given pair x (t) and y (t) is _______
The given pair x (t) & y (t) is related by y (t) = d/dt (x (t))
a) Y (t) = d/dt (x (t))
b) Y (t) = ∫x (t).dt
c) Y (t) = x (t) -1
d) Y (t) = x (t) /2
View Answer

Answer: a
Explanation: The given pair x (t) and y (t) is related by y (t) = d/dt (x (t)). From -2 to 2 we have Y (t) is zero because differentiation of constant is zero.
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10. The given pair x (t) and y (t) is related by _______
The given pair x (t) & y (t) is related by Y (t) = ∫x (t) .dt
a) Y (t) = d/dt (x (t))
b) Y (t) = x (t) + 1
c) Y (t) = ∫x (t) .dt
d) Not related
View Answer

Answer: c
Explanation: The given pair x (t) and y (t) is related by Y (t) = ∫x (t) .dt. The integral of x (t) gives the Y (t). Y (t) = 0 for t > 1.

Sanfoundry Global Education & Learning Series – Signals & Systems.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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