Digital Communications Questions and Answers Part-1

1. How many bytes does a gigabyte have?
a) 1 billion bytes
b) 10 billion bytes
c) 1 million bytes
d) 10 million bytes

Answer: a
Explanation: One gigabyte has 1 billion bytes

2. Equalizer is used for?
a) Filtering
b) Diminish distortion
c) All of the above
d) None of the above

Answer: c
Explanation: Equalizer is used as a filtering option and also diminishes or reduces the distortion.

3. Which block or device does the data compression?
a) Modulator
b) Source encoder
c) Channel encoder
d) None of the above

Answer: b
Explanation: Source encoder converts the digital or analog signal to a sequence of binary digits. This process is called as source encoding or compression.

4. The size of the alphabet M in symbol is calculated as?
a) 2k
b) 1+2k
c) 2(k+1)
d) 2(k-1)

Answer: a
Explanation: The size of the alphabet is calculated using 2k where k is the number of bits in the symbol.

5. What are the advantages of digital circuits?
a) Less interference
b) Less noise
c) More flexible
d) All of the above

Answer: d
Explanation: Digital circuits are less subject to noise, distortion and interference as it works on digital pulses and also the pulses can be regenerated.

6. What is the code rate?
a) n/k
b) k/n
c) All of the above
d) None of the above

Answer: b
Explanation: Here n is the total bits of sequence and k bits are mapped. Amount of redundancy introduced is given by n/k and its reciprocal is the code rate.

7. Source coding block is used for?
a) Digitizing
b) A/D conversion
c) Compressing
d) All of the above

Answer: d
Explanation: Source encoding does all these processes-compression, digitizing the signal and performs analog to digital conversion.

8. What is the ASCII value of space?
a) 48
b) 65
c) 32
d) 96

Answer: c
Explanation: The ASCII value of space is 32 and ASCII value of 0 is 48

9. Which circuit is called as regenerative repeaters?
a) Analog circuits
b) Digital circuits
c) A/D converters
d) Amplifiers

Answer: b
Explanation: The main advantage of digital communication is that the signals can be reproduced easily. Thus digital circuits are called as regenerative repeaters.

10. Pulse shaping is done by which block or system?
a) Demodulator
b) Encoder
c) Pulse code modulator
d) Baseband modulator

Answer: c
Explanation: Pulse code modulator does filtering process to build pulses that occupy more than one bit time.