Digital Modulation Techniques Quiz | Digital Modulation Techniques Short Questions and Answers

Questions
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

Answer: 4 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

Answer: r = k/n
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

Answer: 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

Answer: Power saving
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

Answer: 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

Answer: 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

Answer: Line coding
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

Answer: 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

Answer: All of the above
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