Communications Engineering Coaching Materials: Section 5 Module 1

This is the Section 5 Module 1 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 1

This is the Section 5 Module 1 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 1

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Questions

Answers

1

Amplitude modulation via Facsimile

A3C

2

Frequency modulation via Facsimile

F3C

3

What emission is F3C?

Facsimile

4

Troposcatter in Sky Wave Propagation occurs in what range of frequency

300 MHz to 3 GHz

5

Which of the following terrain types permits a ground wave to travel the farthest?

Salty

6

What of the following permits a microwave signal to travel in one direction with virtually no loss, but severely attenuates any signal attempting to travel in the reverse direction?

Isolator

7

Ferrite rod device that prevents the formation of reflected waves

Isolator

8

Advantage of Trap Antenna

It can be use in different antenna because of LC circuit

9

In Pulse Width Modulation,

pulse duration

10

varying pulses

pulse width modulation

11

Expose ground equipment should not exceed ____ Vrms

45

12

Typical earth factor

4/3

13

Directivity is

Proportional to Antenna gain

14

Current node in a half wave antenna is located

at the ends

15

Voltage node in a half wave antenna is located

at the feed

16

from zero modulation to 100% modulation,

Antenna current increases by 22.5 %

17

The standard reference antenna for a directive gain is

Isotropic Antenna

18

How much farther does the radio path horizon distance exceeds the geometric horizon?

Increases by about 15% of the length

19

Parasitic element

5% longer

20

use in aircraft

Frequency modulated continuous wave

21

Antenna use in ILS

folded dipole continuous wave

22

Why is nitrogen gas sometimes used in waveguide?

to keep the waveguide dry

23

Need for pressurizing cable with dry air

to prevent internal arcing

24

As electromagnetic travel in free space, only one if the following can happen to them

Attenuation

25

Which of the following is not a natural ways of radio wave may travel from transmitter to receiver?

Microwave

26

hollow conductor that carries RF

Waveguide

27

Telephone

13 kbps

28

In a ¾ wavelength shorted at end will have impedance

Infinite

29

What is major cause of atmospheric or static noise?

Thunderstorms

30

What signal to noise ratio is required for satisfactory telephone service?

50 dB

31

In SSB, carrier and the other sideband is being

cancel, filter

32

IBM

83B

33

folded dipole compared to simple dipole

longer

34

In CCITT’s FDM Hierarchy, number of channels in a master group

300

35

Power HF compared to UHF

100:20

36

The third symbol used for television transmission

F

37

A word in telegraphy consists of ___ characters plus a word space

7 and ½

38

VOR

108.1 to 117.95 MHz

39

Class D AM

12 Midnight to 5 AM

40

Trap antenna

can be use in wideband

41

What is the typical speech coding rate used for GSM?

13 kbps

42

D-AMPS

8 kbps

43

Difference between available power and power budget

Power Margin

44

Maximum number of break in a 60 minute show

7

45

2.5:1

46

Unmodulated carrier

0% modulation

47

Frequency band of U600

564-3084

48

What is the transmission rate of a T3 line?

44.736 Mbps

49

in telephone, maximum pulse per second

6

50

third symbol emission for telephone

E

51

Monochromatic

one color and one

52

Quality

Contrast

53

To couple energy into and out of a waveguide

use thin piece of wire as an antenna

54

A high standing wave ratio might be caused by

impedance mismatch

55

VHF received from 500 miles

tropospheric ducting

56

Oldest multiplexing scheme

Space Division Multiplexing

57

1st Active Satellite

Sputnik 1

58

1st Satellite to Transmit and Receive

Intelsat 1

59

Primetime block of TV

6 PM to 11 PM

60

Determine from the following radio frequency that falls under the very high frequency band of radio spectrum

235.50 MHz

61

Antenna power times the Antenna gain

Effective Radiated Power (ERP)

62

Antenna power times the Antenna gain relative to Isotropic antenna

Effective Isotropic Radiated Power (EIRP)

63

Factors

Antenna height, distance

64

It is the picture quality determined by the difference of the intensity between black and white parts of the picture

Contrast

65

Pilot tone

3000 Hz

66

GMA 7

High VHF

67

Amount of voltage induced in a wave by an EM wave

Proportional to Field Strength

68

Disadvantage of Trap antenna

It radiates harmonics

69

An instrument used to measure the relevant height, a layer in the ionosphere used for wave propagation

Ionosonde

70

Third symbol of emission designation using telephone (telephony) such as in sound broadcasting

E

71

Capacitor

Capacitor

72

Commonly used insulator

Mica

73

Distance to the station, DME

Slant distance

74

What phenomenon causes of longer radio path to exceed geometric horizon?

Refraction

75

Waveguide construction

should not have a long horizontal run

76

Loading coil is used in marconi

tuning out capacitance reactances

77

Last stage of GSM

EDGE

78

Bandwidth of fiber optics compared to cable

100 times

79

What causes the attenuation in waveguide?

losses in the conducting walls

80

Continuous tone generated by the combination of two frequencies of 350 Hz and 440 Hz used in telephone sets

Call Waiting tone

81

Pulse dialing rate

10 pulses/sec

82

What kind of receiver is used in conventional telephone handset?

Electromagnet

83

Characteristic impedance is dependent on

length

84

Velocity of sound

330 m/s

85

Time for the signal to travel

Propagation delay

86

How many voice band channels in a SPADE FDMA satellite system are PCM encoded before they separately modulate the assigned carrier?

800

87

AMPS operated in which cellular radio frequency?

800 MHz

88

Which of the following represents the best standing wave ratio?

1:1

89

The _____ of a sound is a subjective effect which is a function of the ear and brain

loudness

90

OMEGA measures

phase angle

91

LORAN

measures at larger distance

92

Radiation resistance

equivalent resistance that will dissipate the same amount

93

What antennas are suitable for direct connection to a waveguide?

Horn and slot antenna

94

What factors determines the EIRP required by a station in each operation?

Satellite antennas and height, Satellite receiver sensitivity

95

Ferrite beads

use in primary and secondary

96

aircracft radio altimeter

4250 MHz to 4350 MHz

97

end impedance of half-wave dipole

2500 ohms

98

aircraft VHF communication

118.00 MHz to 139.975 MHz

99

The bending of radio waves passing over the top of a mountain range that disperses a weak portion of the signal behind the mountain is

knife-edge diffraction

100

troposcatter

beyond 5000 km

101

Information about satellite send to earth

TTC

Complete List of Communications Engineering Coaching Materials


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