Communications Engineering Coaching Materials: Section 5 Module 4

This is the Section 5 Module 4 of the compiled Communications Coaching Materials taken from different sources including but not limited to Communications books, past Board Exams Questions, Journals and the Internet.

Communications Coaching Materials: Section  5 Module 4

This is the Section 5 Module 4 of the compiled Communications Coaching Materials taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies (EST), Communications Books, Journals and other Communications References. This particular Coaching Notes in Communications Engineering has random Questions and Answers in random topics. Make sure to familiarize each questions to increase the chance of passing the ECE Board Exam.

Communications Engineering Coaching: Section 5 Module 4

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Questions

Answers

1

To connect coaxial to a parallel wire

balun

2

Gain of an isotropic antenna

0 dB

3

What is the term used for an equivalent resistance that would dissipate the same amount?

radiation resistance

4

Resulting from obstruction losses

log normal fading

5

Radiation pattern of a discone

omnidirectional

6

Band of light waves

ultraviolet

7

Which of the following antennas receives signals from all direction in horizontal plane?

vertical marconni antenna

8

What happens to beamwidth?

the beamwdith increases as the gain is increased

9

3:00 PM is a standard time

2100 UTC

10

What is the total resistance of an antenna system?

radiation resistance + ohmic resistance

11

In which crosstalk dBx ????????

1pW

12

How can be antenna efficiency ????????????

by installing a good ground radar system

13

What optical source radiates light in all directions?

lambertian source

14

What is the protocol that is used in transferring files?

X modem

15

What signal to noise ratio for satisfactory TV?

40 dB

87

cable consists of twisted pairs of conductors, each separately insulated

Quad

88

stereophonic FM

30 -53 KHz

89

signal to noise ratio required for satisfactory TV reception

40 dB

90

Start of test for BISYNC

STX

91

Short bit sequence 128 bits

hash

92

rules and description binary

V.1

93

affected by the distance

loudness

94

information about satellite send to earth

TTC

95

if away from source

plane wave

96

measures speed

doppler’s effect

97

measures virtual height of ionosphere

ionosonde

98

sound travels fastest at

solid

16

What is the GPS ???????????????

100meters ,95% of the time

17

According to the nyquist theory the sampling rate is _____

twice the highest frequency

18

It consists of a number of dipoles

broadside array

19

Line of sight mode of propagation

space or direct wave

20

What causes a maximum frequency Vary ???????????????

the amount of radiation received from the sun

21

The low power short range wireless technology

bluetooth

22

What is the insertion loss of connector splices?

0.38dB

23

Which of the following frequency is normally used in safety communication?

2174.5 kHz

24

What determine the ability of a radar?

antenna directivity

25

What is the meaning of velocity factor?

the velocity of the wave divided by the velocity of light

26

For T carrier system, T3 has a bit rate of _____

44.736Mbps

27

A half wave antenna operates at very high efficiency ____

because the conductor resistance is low compared to the radiation resistance

28

Process of a signing pcm codes absolute magnitudes

quantizing

29

What distortion is does not cause by TL characteristics?

spacing bias distortion

30

After IF stages

local oscillator

31

Spot in the visible surface of the sun

sun spot

32

What is the number pins of R232 C?

25

33

What for the ratio of radiation resistance to the total resistance?

antenna efficiency

34

What is the reference tone level for dbm?

-90dBm

35

What is the quantization signal to noise ratio if an 8 bit PCM is used?

50dB

36

Which is space diversity?

two or more antennas operating in the same frequency

37

The lowest layer in the ionosphere

D

38

What causes a interference?

poor front end selectivity

39

Cross modulation in the receiver is eliminated at the ____

detector stage

40

Which of the ff antennas require good grounding?

marconni antenna

41

In an FM receiver which circuit is used amplitude variations

limiter

42

What deviation is measured for an angle?

horizontal

43

What is the minimum propagation delay for stationary satellites?

230 milliseconds

44

A unique character is transmitted at the beginning of each message

asynchronous

45

Ku band

14/11 GHz

46

tv receiver that separates sound

radio detector

47

the TACAN is a nav aid providing ___

bearing and distance indication

48

What is the spectrum of FM signal?

30-50kHz

49

What is the emission designation of single sound reduced carrier signal?

R3E

50

the mid-range frequency range of sound is

256-2048Hz

51

the standard deviation of in transmission loss should not exceed

1dB

52

modem are required to connect

the telephone network will pass DC

53

What kind of impedance 1/8 wavelength TL present to a generator?

an inducting reactance

54

What noise is short duration?

impulse noise

55

What is the channel spacing of ???????????

500Hz

56

How is antenna efficiency computed?

efficiency = radiation resistance divided by total resistance X 100%

57

an absorption loss caused by valence electron

ultraviolet absorption

58

is a device in data transmission to interface a data to analogue

modem

59

What is the most commonly used IF of radar receivers?

30MHz

60

layer that exist only during daylight

F1 layer

61

Frequency spectrum ??????

30-53kHz

62

Attenuates signals that passes frequency below

bandstop

63

skip zone

zone of silence

64

Station in the mobile service not intended to use

land station

65

The letter number designation B8E

independent sideband

66

What is the typical separation between two conductors?

0.635 – 15cm

67

Which of the following pulse modulation is ???????????

EWX ??????????

68

Connecting an antenna electrically add a

coil

69

An ITU-T that deals with the telephone circuits

V series

70

Cause some frequency to be delayed with respect to other frequency

phase shift

71

Occurs when a microwave beam is at point

diffraction

72

The input signal of a TWT

cathode end of a helix

73

An equipment used to measure SWR

reflectometer

74

Is a standard where mobile phone can access to specially tailored internet websites

WAP

75

In what region of the world is sporadic E

equatorial regions

76

A radio communication service used for aeronautical safety navigation

aeronautical fixed service

77

What kind of impedance ¼ wavelength?

a very low impedance

78

Propagation mode microwave

TE

79

How far is the visual carrier of monochrome TV channel?

1.25MHz

80

A helical antenna is used for satellite tracking

circular polarization

81

What is ascending pass for a LEO?

from south to north

82

A properly connected Transmission Line has a ____

SWR as near as 1:1 as possible

83

What is the primary advantage of ?????????????

no transmitted power is wasted in the carrier

84

What device is used in diverting electromagnetic?

waveguide switch

85

A type of underground antenna

hertz antenna

86

A type of array which contains of 1 half wave dipole, 1 reflector and 1 director

Yagi uda

87

What happens to a path wave as it is shorted through the use of loading coils?

decreased

88

What do you call the incident light that have different refractive indeces?

reflection

89

What is the standard test tone used for audio measurements?

1000 Hz

90

Capture effect is most pronounced in what type of emission

FM

91

What is the GPRS uplink rate?

14kbps

92

What is the advantage of Doherty linear?

high efficiency

93

Frequency of VCR control signal

30 Hz

94

A type of microphone which has a permanent magnet

ribbon

95

Block calls delays

Erlang C

96

On a telephone system, the loop is open during ___

on hook condition

97

A telephone line connecting two central offices

trunk

98

The SPL in dB of an auditorium with contemporary music is ___

95 -100

Complete List of Communications Engineering Coaching Materials


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