Communications (Test 4)

Gate Exam : Ec Electronics And Communication Engineering

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Communications

Communications
| Communications | | Communication Systems |
Q.1
Which of these is an example of point to point communication?
A. FM Radio
B. AM Radio
C. Telephony
D. TV
Answer : Option C
Explaination / Solution:

In point to point communication,communication occurs over a link between a single transmitter and receiver.Telephony is an example of it as it needs a link between caller and receiver to transmit the information.This link is provided by various media like cable.

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Q.2
Noise in electronic communication refers to
A. Noise produced by sound
B. signals that are amplified for performance
C. Noise produced by whistles
D. unwanted signals that are mixed up with messages
Answer : Option D
Explaination / Solution:

In communication systems, noise is an error or undesired random disturbance of a useful information signal. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources.Consequently,a distored or corrupted version of the transmitted signal reaches the receiver.

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Q.3
Demodulation is
A. Removing the low frequency signals from the received signal
B. Recovering the high frequency modulating signal from the received signal
C. Recovering the low frequency modulating signal from the received signal
D. Removing the high frequency signals from the received signal
Answer : Option C
Explaination / Solution:

Demodulation is extracting the original information-bearing signal from a modulated carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave.

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Q.4
Transmission bandwidth of fiber optic communication can be up to
A. 100 Hz
B. 110 kHz
C. 100 GHz
D. 416 MHz
Answer : Option C
Explaination / Solution:
No Explaination.


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Q.5
baseband signal refers to the
A. signal containing the message or information before modulation
B. signal containing the message or information during modulation
C. signal containing the message or information just after receiving
D. signal containing the message or information after modulation
Answer : Option A
Explaination / Solution:
No Explaination.


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Q.6
The raised cosine pulse p(t) is used for zero ISI in digital communications. The expression for p(t) with unity roll-off factor is given by

The value of p(t) at t = 1/W is
A. −0.5
B. 0
C. 0.5
D.
Answer : Option C
Explaination / Solution:



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Q.7
A right circularly polarized (RCP) plane wave is incident at an angle 600 to the normal, on an air-dielectric interface. If the reflected wave is linearly polarized, the relative dielectric constant ξr is.

A. √2
B. √3
C. 2
D. 3
Answer : Option D
Explaination / Solution:
No Explaination.


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Q.8
One end of a loss-less transmission line having the characteristic impedance of 75Ω and length of 1 cm is short-circuited. At 3 GHz, the input impedance at the other end of transmission line is
A. 0
B. Resistive
C. Capacitive
D. Inductive
Answer : Option D
Explaination / Solution:



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Q.9
Which of the following statements is true regarding the fundamental mode of the metallic waveguides shown ?

A. Only P has no cutoff-frequency
B. Only Q has no cutoff-frequency
C. Only R has no cutoff-frequency
D. All three have cutoff-frequencies
Answer : Option A
Explaination / Solution:

Rectangular and cylindrical waveguide doesn’t support TEM modes and have cut off frequency. Coaxial cable support TEM wave and doesn’t have cut off frequency.


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Q.10
In the circuit shown, all the transmission line sections are lossless. The Voltage Standing Wave Ration(VSWR) on the 60 Ω line is

A. 1.00
B. 1.64
C. 2.50
D. 3.00
Answer : Option B
Explaination / Solution:




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EC Electronics and Communication Engineering