Digital Modulation Techniques Quiz | Digital Modulation Techniques Objective Type Questions and Answers

Questions
21 Run Length Encoding is used for
A Correction of error in multiple bits
B Bit error correction
C Reducing the repeated string of characters
D All of the above

Answer: All of the above
22 Parity check bit coding is used for
A Error detection
B Error correction and detection
C Error correction
D None of the above

Answer: Error detection
23 Parity bit coding may not be used for
A Error in more than single bit
B Which bit is in error
C Both a & b
D None of the above

Answer: Both a & b
24 For a (7, 4) block code, 7 is the total number of bits and 4 is the number of
A Information bits
B Redundant bits
C Total bits- information bits
D None of the above

Answer: Information bits
25 Interleaving process permits a burst of B bits, with l as consecutive code bits and t errors when
A B ≤ 2tl
B B ≥ tl
C B ≤ tl/2
D B ≤ tl

Answer: B ≤ tl
26 The code in convolution coding is generated using
A EX-OR logic
B OR logic
C AND logic
D None of the above

Answer: EX-OR logic
27 For decoding in convolution coding, in a code tree,
A Diverge right when a bit is 0 and diverge left when the bit is 1
B Diverge upward when a bit is 0 and diverge downward when the bit is 1
C Diverge downward when a bit is 0 and diverge upward when the bit is 1
D Diverge left when a bit is 0 and diverge right when the bit is 1

Answer: Diverge upward when a bit is 0 and diverge downward when the bit is 1
28 A linear code
A Minimum hamming distance between two code words is equal to weight of any non zero code word
B Sum of code words is also a code word
C All-zero code word is a code word
D All of the above

Answer: All of the above
29 Graphical representation of linear block code is known as
A Pi graph
B Matrix
C Tanner graph
D None of the above

Answer: Tanner graph
30 Synchronization of signals is done using
A Transmitter and receiver connected to master timing source
B Extracting timing information from the received signal
C Pilot clock
D All of the above

Answer: All of the above
31 In coherent detection of signals,
A The carrier is in synchronization with modulated carrier
B Carrier of frequency and phase as same as transmitted carrier is generated
C Local carrier is generated
D All of the above

Answer: All of the above
32 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
33 ISI may be removed by using
A Polar NRZ
B Differential coding
C Manchester coding
D None of the above

Answer: Differential coding
34 Overhead bits are
A Encoded bits
B Framing and synchronizing bits
C Data due to noise
D None of the above

Answer: Framing and synchronizing bits
35 The expected information contained in a message is called
A Entropy
B Coded signal
C Efficiency
D None of the above

Answer: Entropy
36 The information I contained in a message with probability of occurrence is given by (k is constant)
A I = k log21/P2
B I = k log2P
C I = k log21/P
D I = k log21/2P

Answer: I = k log21/P
37 The memory less source refers to
A Emitted message is independent of previous message
B No previous information
C No message storage
D None of the above

Answer: Emitted message is independent of previous message
38 Entropy is
A Average information per message
B Information in a signal
C Amplitude of signal
D All of the above

Answer: Average information per message
39 The relation between entropy and mutual information is
A I(X;Y) = H(X) – H(X/Y)
B I(X;Y) = H(X/Y) – H(Y/X)
C I(X;Y) = H(X) – H(Y)
D I(X;Y) = H(Y) – H(X)

Answer: I(X;Y) = H(X) – H(X/Y)
40 The mutual information
A Is symmetric
B Always non negative
C Both a and b are correct
D None of the above

Answer: Both a and b are correct
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