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Free download in PDF Digital Modulation Techniques Short Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
41
The information rate R for given average information H= 2.0 for analog signal band limited to B Hz is
[A]
16 B bits/sec
[B]
2 B bits/sec
[C]
4 B bits/sec
[D]
8 B bits/sec
42
Code rate r, k information bits and n as total bits, is defined as
[A]
r = k/n
[B]
k = n/r
[C]
r = k * n
[D]
n = r * k
43
The technique that may be used to increase average information per bit is
[A]
Shannon-Fano algorithm
[B]
ASK
[C]
FSK
[D]
Digital modulation techniques
Answer: Shannon-Fano algorithm
44
For a binary symmetric channel, the random bits are given as
[A]
Logic 1 given by probability P and logic 0 by (1-P)
[B]
Logic 1 given by probability 1-P and logic 0 by P
[C]
Logic 1 given by probability P2 and logic 0 by 1-P
[D]
Logic 1 given by probability P and logic 0 by (1-P)2
Answer: Logic 1 given by probability P and logic 0 by (1-P)
45
The channel capacity according to Shannon’s equation is
[A]
Information transmitted
[B]
Defined for optimum system
[C]
Maximum error free communication
[D]
All of the above
46
In DPSK technique, the technique used to encode bits is
[A]
AMI
[B]
Differential code
[C]
Uni polar RZ format
[D]
Manchester format
Answer: Differential code
47
Alternate Mark Inversion (AMI) is also known as
[A]
Pseudo ternary coding
[B]
Manchester coding
[C]
Polar NRZ format
[D]
None of the above
Answer: Pseudo ternary coding
48
The advantage of using Manchester format of coding is
[A]
Power saving
[B]
Polarity sense at the receiver
[C]
Noise immunity
[D]
None of the above
49
The maximum synchronizing capability in coding techniques is present in
[A]
Polar RZ
[B]
Polar NRZ
[C]
Manchester format
[D]
None of the above
Answer: Manchester format
50
The format in which the positive half interval pulse is followed by a negative half interval pulse for transmission of ‘1’ is
[A]
Polar NRZ format
[B]
Bipolar NRZ format
[C]
Manchester format
[D]
None of the above
Answer: Manchester format
51
The polarities in NRZ format use
[A]
Complete pulse duration
[B]
Half duration
[C]
Both positive as well as negative value
[D]
Each pulse is used for twice the duration
Answer: Complete pulse duration
52
Impulse noise is caused due to
[A]
Power line load switching
[B]
Lightening strikes
[C]
Switching transients
[D]
All of the above
53
Polar coding is a technique in which
[A]
1 is transmitted by a positive pulse and 0 is transmitted by negative pulse
[B]
1 is transmitted by a positive pulse and 0 is transmitted by zero volts
[C]
Both a & b
[D]
None of the above
Answer: 1 is transmitted by a positive pulse and 0 is transmitted by negative pulse
54
In a uni-polar RZ format,
[A]
The waveform has zero value for symbol ‘0’
[B]
The waveform has A volts for symbol ‘1’
[C]
The waveform has positive and negative values for ‘1’ and ‘0’ symbol respectively
[D]
Both a and b are correct
Answer: Both a and b are correct
55
Scrambling of data is
[A]
Removing long strings of 1’s and 0’s
[B]
Exchanging of data
[C]
Transmission of digital data
[D]
All of the above
Answer: Removing long strings of 1’s and 0’s
56
Regenerative repeaters are used for
[A]
Transmission over long distances
[B]
Reconstruction of signals
[C]
Eliminating noise
[D]
All of the above
57
For a line code, the transmission bandwidth must be
[A]
Maximum possible
[B]
As small as possible
[C]
Depends on the signal
[D]
None of the above
Answer: As small as possible
58
The process of coding multiplexer output into electrical pulses or waveforms for transmission is called
[A]
Line coding
[B]
Amplitude modulation
[C]
FSK
[D]
Filtering
59
Matched filters may be used
[A]
To estimate the distance of the object
[B]
In parameter estimation problems
[C]
To estimate the frequency of the received signal
[D]
All of the above
60
Characteristics of Matched filter are
[A]
They are used for signal detection
[B]
It gives the output as signal energy in the absence of noise
[C]
Matched filter is used to maximize Signal to noise ratio even for non Gaussian noise
[D]
All of the above
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