Digital Communication 3

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Electronic Engineering MCQ Question Papers: ENTC, IT Interview Placement

Subject: Digital Communication 3

Part 3: List for questions and answers of Digital Communication

 

Q1. In Alternate Mark Inversion (AMI) is

a) 0 is encoded as positive pulse and 1 is encoded as negative pulse

b) 0 is encoded as no pulse and 1 is encoded as negative pulse

c) 0 is encoded as negative pulse and 1 is encoded as positive pulse

d) 0 is encoded as no pulse and 1 is encoded as positive or negative pulse

 

Q2. Advantages of using AMI

a) Needs least power as due to opposite polarity

b) Prevents build-up of DC

c) May be used for longer distance

d) All of the above

 

Q3. The interference caused by the adjacent pulses in digital transmission is called

a) Inter symbol interference

b) White noise

c) Image frequency interference

d) Transit time noise

 

Q4. Eye pattern is

a) Is used to study ISI

b) May be seen on CRO

c) Resembles the shape of human eye

d) All of the above

 

Q5. The time interval over which the received signal may be sampled without error may be explained by

a) Width of eye opening of eye pattern

b) Rate of closure of eye of eye pattern

c) Height of the eye opening of eye pattern

d) All of the above

 

Q6. For a noise to be white Gaussian noise, the optimum filter is known as

a) Low pass filter

b) Base band filter

c) Matched filter

d) Bessel filter 

 

Q7. Matched filters are used

a) For maximizing signal to noise ratio

b) For signal detection

c) In radar

d) All of the above

 

Q8. The number of bits of data transmitted per second is called

a) Data signalling rate

b) Modulation rate

c) Coding

d) None of the above

 

Q9. Pulse shaping is done

a) to control Inter Symbol Interference

b) by limiting the bandwidth of transmission

c) after line coding and modulation of signal

d) All of the above

 

Q10. The criterion used for pulse shaping to avoid ISI is

a) Nyquist criterion

b) Quantization

c) Sample and hold

d) PLL

 

Q11. The filter used for pulse shaping is

a) Raised – cosine filter

b) Sinc shaped filter

c) Gaussian filter

d) All of the above

 

Q12. Roll – off factor is defined as

a) The bandwidth occupied beyond the Nyquist Bandwidth of the filter

b) The performance of the filter or device

c) Aliasing effect

d) None of the above

 

Q13. Nyquist criterion helps in

a) Transmitting the signal without ISI

b) Reduction in transmission bandwidth

c) Increase in transmission bandwidth

d) Both a and b 

 

Q14. The Nyquist theorem is

a) Relates the conditions in time domain and frequency domain

b) Helps in quantization

c) Limits the bandwidth requirement

d) Both a and c

 

Q15. The difficulty in achieving the Nyquist criterion for system design is

a) There are abrupt transitions obtained at edges of the bands

b) Bandwidth criterion is not easily achieved

c) Filters are not available

d) None of the above

 

Q16. Equalization in digital communication

a) Reduces inter symbol interference

b) Removes distortion caused due to channel

c) Is done using linear filters

d) All of the above

 

Q17. Zero forced equalizers are used for

a) Reducing ISI to zero

b) Sampling

c) Quantization

d) None of the above

 

Q18. The transmission bandwidth of the raised cosine spectrum is given by

a) Bt = 2w(1 + α)

b) Bt = w(1 + α)

c) Bt = 2w(1 + α)

d) Bt = 2w(2 + α)

 

Q19. The preferred orthogonalization process for its numerical stability is

a) Gram- Schmidt process

b) House holder transformation

c) Optimization

d) All of the above 

 

Q20. For two vectors to be orthonormal, the vectors are also said to be orthogonal. The reverse of the same

a) Is true

b) Is not true

c) Is not predictable

d) None of the above 

 

Part 3: List for questions and answers of Digital Communication

 

Q1. Answer: d

 

Q2. Answer: d

 

Q3. Answer: a

 

Q4. Answer: d

 

Q5. Answer: a

 

Q6. Answer: c

 

Q7. Answer: d

 

Q8. Answer: a

 

Q9. Answer: d

 

Q10. Answer: a

 

Q11. Answer: d

 

Q12. Answer: a

 

Q13. Answer: d

 

Q14. Answer: d

 

Q15. Answer: a

 

Q16. Answer: d

 

Q17. Answer: a

 

Q18. Answer: a

 

Q19. Answer: b

 

Q20. Answer: c