Physical Layer and Transmission Media MCQs

This Portion of Computer Networking contains Computer Networking Physical Layer and Transmission Media MCQs (Multiple Choice Questions and Answers).

This Section covers below lists of topics.

1 DATA AND SIGNALS
• Analog and Digital
• Transmission Impairment
• Data Rate Limits
• Performance

2 DIGITAL TRANSMISSION
• Digital-to-Digital Conversion
• Analog-to-Digital Conversion

3 ANALOG TRANSMISSION
• Digital-to-Analog Conversion
• Analog-to-Analog Conversion

4 BANDWIDTH UTILIZATION
• Multiplexing
• Spread Spectrum

5 TRANSMISSION MEDIA
• Guided Media
• Unguided Media: Wireless

PRACTICE IT NOW TO SHARPEN YOUR CONCEPT AND KNOWLEDGE

1. As frequency increases, the period ________.

decreases
increases
remains the same
None of the choices are correct.

2. ________ is a type of transmission impairment in which the signal loses strength due to the resistance of the transmission medium.

Attenuation
Distortion
Noise
Decibel

3. ________ is a type of transmission impairment in which the signal loses strength due to the different propagation speeds of each frequency that makes up the signal.

Attenuation
Distortion
Noise
Decibel

4. ________ is a type of transmission impairment in which an outside source such as crosstalk corrupts a signal.

Attenuation
Distortion
Noise
Decibel

5. When propagation speed is multiplied by propagation time, we get the ________.

throughput
wavelength of the signal
distortion factor
distance a signal or bit has traveled

6. Baseband transmission of a digital signal is possible only if we have a ____ channel.

low-pass
bandpass
low rate
high rate

7. If the available channel is a ____ channel, we cannot send a digital signal directly to the channel.

low-pass
bandpass
low rate
high rate

8. For a ______ channel, the Nyquist bit rate formula defines the theoretical maximum bit rate.

noisy
noiseless
bandpass
low-pass

9. For a ______ channel, we need to use the Shannon capacity to find the maximum bit rate.

noisy
noiseless
bandpass
low-pass

10. _________ can impair a signal.

Attenuation
Distortion
Noise
All of the choices are correct.

11. The _________ product defines the number of bits that can fill the link.

bandwidth-period
frequency-amplitude
bandwidth-delay
delay-amplitude

12. Polar and bipolar encoding are types of _______ coding.

line
block
scrambling
None of the choices are correct.

13. ___________ conversion involves three techniques: line coding, block coding, and scrambling.

Analog-to-digital
Digital-to-analog
Analog-to-analog
Digital-to-digital

14. In ______ schemes, the voltage level oscillates between a positive and a negative values although it may remain at zero level between the two values.

polar
bipolar
nonpolar
None of the choices are correct.

15. In _____, the level of the voltage determines the value of the bit.

NRZ-I
NRZ-L
NRZ-I or NRZ-L
None of the choices are correct.

16. In ______, the change or lack of change in the level of the voltage determines the value of the bit.

NRZ-I
NRZ-L
NRZ-I or NRZ-L
None of the choices are correct.

17. The idea of RZ and the idea of NRZ-L are combined into the ________ scheme.

Manchester
differential Manchester
Manchester or differential Manchester
None of the choices are correct.

18. The idea of RZ and the idea of NRZ-I are combined into the ________ scheme.

Manchester
differential Manchester
Manchester or differential Manchester
None of the choices are correct.

19. In Manchester and differential Manchester encoding, the transition at the middle of the bit is used for __________.

bit transfer
baud transfer
synchronization
None of the choices are correct.

20. In _______ encoding, we use three levels: positive, zero, and negative.

polar
bipolar
nonpolar
None of the choices are correct.

21. The _____ scheme uses data patterns of size 2 and encodes the 2-bit patterns as one signal element belonging to a four-level signal.

4B5B
2B1Q
B8ZS
None of the choices are correct.

22. _______ encoding has a transition at the middle of each bit.

RZ
Manchester
Differential Manchester
All the choices are correct.

23. _______ encoding has a transition at the beginning of each 0 bit.

RZ
Manchester
Differential Manchester
All the choices are correct.

24. Which of the following encoding methods does not provide for synchronization?

NRZ-L
RZ
NRZ-I
Manchester

25. Which encoding method uses alternating positive and negative values for 1s?

NRZ-I
RZ
Manchester
AMI

26. Block coding can help in _ and ___ at the receiver.

synchronization and error detection
synchronization and attenuation
error detection and attenuation
error detection and distortion

27. ________ is the process of converting digital data to a digital signal.

Block coding
Line coding
Scrambling
All of the choices are correct.

28. _______ provides redundancy to ensure synchronization and inherent error detection.

Block coding
Line coding
Line coding or block coding
None of the choices are correct

29. ________ is normally referred to as mB/nB coding; it replaces each m-bit group with an n-bit group.

Block coding
Line coding
Scrambling
None of the choices are correct.

30. ________ provides synchronization without increasing the number of bits.

Scrambling
Line coding
Block coding
None of the choices are correct.

31. Two common scrambling techniques are ________.

NRZ and RZ
AMI and NRZ
B8ZS and HDB3
Manchester and differential Manchester

32. PCM is an example of _______ conversion.

digital-to-digital
digital-to-analog
analog-to-analog
analog-to-digital

33. The most common technique to change an analog signal to digital data is called __________.

PAL
PCM
sampling
None of the choices are correct.

34. The first step in PCM is ________.

quantization
modulation
sampling
None of the choices are correct.

35. __ finds the value of the signal amplitude for each sample; finds the change from the previous sample.

DM; PCM
PCM; DM
DM; CM
None of the choices are correct.

36. The __ rate defines the number of data elements sent in one second; the rate is the number of signal elements sent in one second.

data; signal
signal; data
baud; bit
none of the choices are correct

37. ASK, PSK, FSK, and QAM are examples of ________ conversion.

digital-to-digital
digital-to-analog
analog-to-analog
analog-to-digital

38. AM, FM, and PM are examples of ________ conversion.

digital-to-digital
digital-to-analog
analog-to-analog
analog-to-digital

39. In QAM, both ________ of a carrier frequency are varied.

frequency and amplitude
phase and frequency
amplitude and phase
none of the choices are correct

40. In ________, the amplitude of the carrier signal is varied to create signal elements. Both frequency and phase remain constant.

41. In _________, the frequency of the carrier signal is varied to represent data. Both peak amplitude and phase remain constant.

42. In ________, the phase of the carrier is varied to represent two or more different signal elements. Both peak amplitude and frequency remain constant.

43. Quadrature amplitude modulation (QAM) is a combination of ___________.

ASK and FSK
ASK and PSK
PSK and FSK
None of the choices are correct.

44. ________ uses two carriers, one in-phase and the other quadrature.

45. How many carrier frequencies are used in BASK?

1
2
3
None of the choices are correct.

46. How many carrier frequencies are used in BFSK?

1
2
3
None of the choices are correct.

47. How many carrier frequencies are used in BPSK?

1
2
3
None of the choices are correct.

48. Which of the following is not an analog-to-analog conversion?

49. In a frequency-domain plot, the horizontal axis measures the ________.

signal amplitude
frequency
phase
time

50. In _____ transmission, the carrier signal is modulated so that its amplitude varies with the changing amplitudes of the modulating signal.

AM
PM
FM
None of the choices are correct.

51. In a time-domain plot, the horizontal axis is a measure of ________.

signal amplitude
frequency
phase
time

52. Which multiplexing technique is used for analog signals?

53. _______ data are continuous and take continuous values.

analog
digital
analog or digital
None of the choices are correct.

54. Which multiplexing technique is used for digital signals?

55. _______ data have discrete states and take discrete values.

analog
digital
analog or digital
None of the choices are correct.

56. Which multiplexing technique shifts each signal to a different carrier frequency?

57. _____ signals have an infinite number of values in a time interval.

Analog
Digital
Either analog or digital
None of the choices are correct.

58. Which multiplexing technique involves signals composed of light beams?

59. _______ signals can have only a limited number of values in a time interval.

Analog
Digital
Either analog or digital
None of the choices are correct.

60. ________ is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link.

Demodulating
Multiplexing
Compressing
None of the choices are correct

61. Frequency and period are ______.

inverse of each other
proportional to each other
the same
are not related

62. ____ is designed to use the high bandwidth capability of fiber-optic cable.

FDM
TDM
WDM
None of the choices are correct.

63. ________ is the rate of change with respect to time.

Amplitude
Time
Frequency
Phase

64. ______ is an analog multiplexing technique to combine optical signals.

FDM
TDM
WDM
None of the choices are correct.

65. _______ describes the position of the waveform relative to time 0.

Amplitude
Time
Frequency
Phase

66. _____ is a digital process that allows several connections to share the high bandwidth of a link.

FDM
TDM
WDM
None of the choices are correct.

67. A simple sine wave can be represented by one single spike in the _____ domain.

amplitude
time
frequency
phase

68. We can divide ____ into two different schemes: synchronous or statistical.

FDM
TDM
WDM
None of the choices are correct.

69. In ________ TDM, each input connection has an allotment in the output even if it is not sending data.

synchronous
statistical
isochronous
None of the choices are correct.

70. In ________ TDM, slots are dynamically allocated to improve bandwidth efficiency.

synchronous
statistical
isochronous
None of the choices are correct.

71. The _______ technique uses M different carrier frequencies that are modulated by the source signal. At one moment, the sign modulates one carrier frequency; at the next moment, the signal modulates another carrier frequency.

FDM
DSSS
FHSS
TDM

72. The ______ technique expands the bandwidth of a signal by replacing each data bit with n bits using a spreading code.

FDM
DSSS
FHSS
TDM

73. Transmission media are usually categorized as _______.

fixed or unfixed
guided or unguided
determinate or indeterminate
metallic or nonmetallic

74. Transmission media lie below the _______ layer.

physical
network
transport
application

75. _______ cable consists of an inner copper core and a second conducting outer sheath.

Twisted-pair
Coaxial
Fiber-optic
Shielded twisted-pair

76. In fiber optics, the signal is _______ waves.

light
radio
infrared
very low-frequency

77. Which of the following is not a guided medium?

twisted-pair cable
coaxial cable
fiber-optic cable
atmosphere

Computer Networking – Physical Layer and Transmission Media MCQs