Digital Communication 4

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Electronic Engineering MCQ Question Papers: ENTC, IT Interview Placement

Subject: Digital Communication 4

Part 4: List for questions and answers of Digital Communication


Q1. Orthonormal set is a set of all vectors that are

a) Mutually orthonormal and are of unit length

b) Mutually orthonormal and of null length

c) Both a & b

d) None of the above


Q2. In On-Off keying, the carrier signal is transmitted with signal value ‘1’ and ‘0’ indicates

a) No carrier

b) Half the carrier amplitude

c) Amplitude of modulating signal

d) None of the above


Q3. ASK modulated signal has the bandwidth

a) Same as the bandwidth of baseband signal

b) Half the bandwidth of baseband signal

c) Double the bandwidth of baseband signal

d) None of the above


Q4. Coherent detection of binary ASK signal requires

a) Phase synchronization

b) Timing synchronization

c) Amplitude synchronization

d) Both a and b


Q5. The probability of error of DPSK is ______________ than that of BPSK

a) Higher

b) Lower

c) Same

d) Not predictable


Q6. In Binary Phase Shift Keying system, the binary symbols 1 and 0 are represented by carrier with phase shift of

a) Π//2

b) Π 

c) 2 Π 

d) 0 


Q7. BPSK system modulates at the rate of

a) 1 bit/ symbol

b) 2 bit/ symbol

c) 4 bit/ symbol

d) None of the above


Q8. The binary waveform used to generate BPSK signal is encoded in

a) Bipolar NRZ format

b) Manchester coding

c) Differential coding

d) None of the above


Q9. The bandwidth of BFSK is ______________ than BPSK.

a) Lower

b) Same

c) Higher

d) Not predictable


Q10. In Binary FSK, mark and space respectively represent

a) 1 and 0

b) 0 and 1

c) 11 and 00

d) 00 and 11


Q11. The frequency shifts in the BFSK usually lies in the range

a) 50 to 1000 Hz

b) 100 to 2000 Hz

c) 200 to 500 Hz

d) 500 to 10 Hz


Q12. The spectrum of BFSK may be viewed as the sum of

a) Two ASK spectra

b) Two PSK spectra

c) Two FSK spectra

d) None of the above


Q13. The maximum bandwidth is occupied by

a) ASK


c) FSK

d) None of the above 


Q14. QPSK is a modulation scheme where each symbol consists of

a) 4 bits

b) 2 bits

c) 1 bits

d) M number of bits, depending upon the requirement


Q15. The data rate of QPSK is ___________ of BPSK.

a) Thrice

b) Four times

c) Twice

d) Same


Q16. QPSK system uses a phase shift of

a)  Π 

b) Π /2

c) Π  /4

d) 2 Π 


Q17. Minimum shift keying is similar to

a) Continuous phase frequency shift keying

b) Binary phase shift keying

c) Binary frequency shift keying



Q18. In MSK, the difference between the higher and lower frequency is

a) Same as the bit rate

b) Half of the bit rate

c) Twice of the bit rate

d) Four time the bit rate


Q19. The technique that may be used to reduce the side band power is

a) MSK


c) Gaussian minimum shift keying



Q20. The BPSK signal has +V volts and -V volts respectively to represent

a) 1 and 0 logic levels

b) 11 and 00 logic levels

c) 10 and 01 logic levels

d) 00 and 11 logic levels 


Part 4: List for questions and answers of Digital Communication


Q1. Answer: b


Q2. Answer: a


Q3. Answer: a


Q4. Answer: d


Q5. Answer: a


Q6. Answer: b


Q7. Answer: a


Q8. Answer: a


Q9. Answer: c


Q10. Answer: a


Q11. Answer: a


Q12. Answer: a


Q13. Answer: c


Q14. Answer: b


Q15. Answer: c


Q16. Answer: b


Q17. Answer: a


Q18. Answer: b


Q19. Answer: c


Q20. Answer: a