1) In DPSK technique, the technique used to encode bits is
a. AMI
b. Differential code
c. Uni polar RZ format
d. Manchester format

2) Synchronization of signals is done using
a. Pilot clock
b. Extracting timing information from the received signal
c. Transmitter and receiver connected to master timing source
d. All of the above

3) In coherent detection of signals,
a. Local carrier is generated
b. Carrier of frequency and phase as same as transmitted carrier is generated
c. The carrier is in synchronization with modulated carrier
d. All of the above

4) Impulse noise is caused due to
a. Switching transients
b. Lightening strikes
c. Power line load switching
d. All of the above

5) Probability density function defines
a. Amplitudes of random noise
b. Density of signal
c. Probability of error
d. All of the above

6) Timing jitter is
a. Change in amplitude
b. Change in frequency
c. Deviation in location of the pulses
d. All of the above

7) ISI may be removed by using
a. Differential coding
b. Manchester coding
c. Polar NRZ
d. None of the above

8) Overhead bits are
a. Framing and synchronizing bits
b. Data due to noise
c. Encoded bits
d. None of the above

9) The expected information contained in a message is called
a. Entropy
b. Efficiency
c. Coded signal
d. None of the above

10) The information I contained in a message with probability of occurrence is given by (k is constant)
a. I = k log_{2}1/P
b. I = k log_{2}P
c. I = k log_{2}1/2P
d. I = k log_{2}1/P^{2}

11) The memory less source refers to
a. No previous information
b. No message storage
c. Emitted message is independent of previous message
d. None of the above
Answer
Explanation
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ANSWER: Emitted message is independent of previous message
Explanation: No explanation is available for this question!


12) Entropy is
a. Average information per message
b. Information in a signal
c. Amplitude of signal
d. All of the above

13) 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)

14) The mutual information
a. Is symmetric
b. Always non negative
c. Both a and b are correct
d. None of the above

15) Information rate is defined as
a. Information per unit time
b. Average number of bits of information per second
c. rH
d. All of the above

16) The information rate R for given average information H= 2.0 for analog signal band limited to B Hz is
a. 8 B bits/sec
b. 4 B bits/sec
c. 2 B bits/sec
d. 16 B bits/sec

17) 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

18) The technique that may be used to increase average information per bit is
a. ShannonFano algorithm
b. ASK
c. FSK
d. Digital modulation techniques

19) For a binary symmetric channel, the random bits are given as
a. Logic 1 given by probability P and logic 0 by (1P)
b. Logic 1 given by probability 1P and logic 0 by P
c. Logic 1 given by probability P^{2} and logic 0 by 1P
d. Logic 1 given by probability P and logic 0 by (1P)^{2}
Answer
Explanation
Related Ques

ANSWER: Logic 1 given by probability P and logic 0 by (1P)
Explanation: No explanation is available for this question!


20) The channel capacity according to Shannon's equation is
a. Maximum error free communication
b. Defined for optimum system
c. Information transmitted
d. All of the above

21) For M equally likely messages, M>>1, if the rate of information R > C, the probability of error is
a. Arbitrarily small
b. Close to unity
c. Not predictable
d. Unknown

22) For M equally likely messages, M>>1, if the rate of information R ≤ C, the probability of error is
a. Arbitrarily small
b. Close to unity
c. Not predictable
d. Unknown

23) The negative statement for Shannon's theorem states that
a. If R > C, the error probability increases towards Unity
b. If R < C, the error probability is very small
c. Both a & b
d. None of the above
Answer
Explanation
Related Ques

ANSWER: If R > C, the error probability increases towards Unity
Explanation: No explanation is available for this question!


24) According to Shannon Hartley theorem,
a. The channel capacity becomes infinite with infinite bandwidth
b. The channel capacity does not become infinite with infinite bandwidth
c. Has a tradeoff between bandwidth and Signal to noise ratio
d. Both b and c are correct

25) The capacity of a binary symmetric channel, given H(P) is binary entropy function is
a. 1  H(P)
b. H(P)  1
c. 1  H(P)^{2}
d. H(P)^{2}  1

26) The channel capacity is
a. The maximum information transmitted by one symbol over the channel
b. Information contained in a signal
c. The amplitude of the modulated signal
d. All of the above
Answer
Explanation
Related Ques

ANSWER: The maximum information transmitted by one symbol over the channel
Explanation: No explanation is available for this question!


27) For M equally likely messages, the average amount of information H is
a. H = log_{10}M
b. H = log_{2}M
c. H = log_{10}M^{2}
d. H = 2log_{10}M

28) The capacity of Gaussian channel is
a. C = 2B(1+S/N) bits/s
b. C = B^{2}(1+S/N) bits/s
c. C = B(1+S/N) bits/s
d. C = B(1+S/N)2 bits/s

29) The probability density function of a Markov process is
a. p(x1,x2,x3.......xn) = p(x1)p(x2/x1)p(x3/x2).......p(xn/xn1)
b. p(x1,x2,x3.......xn) = p(x1)p(x1/x2)p(x2/x3).......p(xn1/xn)
c. p(x1,x2,x3......xn) = p(x1)p(x2)p(x3).......p(xn)
d. p(x1,x2,x3......xn) = p(x1)p(x2 * x1)p(x3 * x2)........p(xn * xn1)
Answer
Explanation
Related Ques

ANSWER: p(x1,x2,x3.......xn) = p(x1)p(x2/x1)p(x3/x2).......p(xn/xn1)
Explanation: No explanation is available for this question!


30) Orthogonality of two codes means
a. The integrated product of two different code words is zero
b. The integrated product of two different code words is one
c. The integrated product of two same code words is zero
d. None of the above
Answer
Explanation
Related Ques

ANSWER: The integrated product of two different code words is zero
Explanation: No explanation is available for this question!


31) The Golay code (23,12) is a codeword of length 23 which may correct
a. 2 errors
b. 3 errors
c. 5 errors
d. 8 errors

32) The minimum distance for unextended Golay code is
a. 8
b. 9
c. 7
d. 6

33) The prefix code is also known as
a. Instantaneous code
b. Block code
c. Convolutional code
d. Parity bit

34) Run Length Encoding is used for
a. Reducing the repeated string of characters
b. Bit error correction
c. Correction of error in multiple bits
d. All of the above

35) For hamming distance d_{min} and number of errors D, the condition for receiving invalid codeword is
a. D ≤ d_{min} + 1
b. D ≤ d_{min}^{  1}
c. D ≤ 1  d_{min}
d. D ≤ d_{min}

36) For hamming distance d_{min} and t errors in the received word, the condition to be able to correct the errors is
a. 2t + 1 ≤ d_{min}
b. 2t + 2 ≤ d_{min}
c. 2t + 1 ≤ 2d_{min}
d. Both a and b

37) Parity check bit coding is used for
a. Error correction
b. Error detection
c. Error correction and detection
d. None of the above

38) 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

39) 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

40) 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

41) The code in convolution coding is generated using
a. EXOR logic
b. AND logic
c. OR logic
d. None of the above

42) For decoding in convolution coding, in a code tree,
a. Diverge upward when a bit is 0 and diverge downward when the bit is 1
b. Diverge downward when a bit is 0 and diverge upward when the bit is 1
c. Diverge left when a bit is 0 and diverge right when the bit is 1
d. Diverge right when a bit is 0 and diverge left when the bit is 1
Answer
Explanation
Related Ques

ANSWER: Diverge upward when a bit is 0 and diverge downward when the bit is 1
Explanation: No explanation is available for this question!


43) A linear code
a. Sum of code words is also a code word
b. Allzero code word is a code word
c. Minimum hamming distance between two code words is equal to weight of any non zero code word
d. All of the above

44) Graphical representation of linear block code is known as
a. Pi graph
b. Matrix
c. Tanner graph
d. None of the above
