Communications Engineering Coaching Materials: Section 5 Module 11

This is the Section 5 Module 11 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 11

This is the Section 5 Module 11 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 11

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Questions

Answers

1

Number of turns of a helix antenna

3

2

Highest layer of the ionosphere during night time

F layer

3

Oxygen causes what attenuation at what frequency

60 GHz

4

One sideband

H3E

5

Thickest layer of the ionosphere

F2

6

F1 and F2 layer combines at night time at what distance

300km

7

Class of Amplifier used at the last stage of AM receiver

class C

8

Front-end “components” of the superheterodyne receiver

local oscillator, mixer, RF amplifier

9

Fiber optic used for electronic communication

semi-graded Fiber Optic

10

Carrier swing at 80% modulation

120 kHz

11

H designates what kind of modulation

single sideband / DSB

12

Used for testing to avoid interference

dummy antenna

13

How to prevent interference with the frequency of other stations during testing

use a dummy antenna

14

data switching is used to

increase rate of data transfer

15

Periscope antenna

shorten waveguide link

16

one hop, full-duplex uses how many receivers

2

17

full duplex multiplexer

two way simultaneous transmission

18

a room with great sound absorption and less reverberation time

dead room

19

measures speech volume

volume unit meter

20

luminance

30% red, 59% green, 11% blue

21

unit of noise power in posphometer

pWp

22

group 1 frequency assignment for color black

2300-2400 Hz

23

group 1 frequency assignment for white

1500 Hz

24

quarter wavelength crystalline calcite device that reverses polarity of the fiber optic communication

retarder

25

Distortion caused by simultaneous frequency and amplitude modulation and carrier frequency

dynamic instability

26

Size of a mini dvd

8cm

27

Size of a standard dvd

12cm

28

Antenna height is _____ of the actual height

½ to 2/3

29

Reference noise power of test tone

1mW

30

Unit of white noise voltage testing measurement

NPR

31

SSB uses ___ of the bandwidth of the DSBSC

½

32

Indicated the maximum channel capacity

Shannon-hartley theory

33

not an advantage of series modulation

suppresses white noise

34

asynchronous protocol is ___ oriented

character

35

V-designation for 4.8 kbps modes

V.27

36

For video 3.4 Mbps

J.81

37

Rid of FM noise

Limiter

38

Advantage of side tone

assure that the telephone is working

39

At what power level does a 1kHz tone cause zero interference (144 weighted)

90 dB

40

Reference frequency of CCITT phosphometer noise measurement

800 Hz

41

device that modulates an analog carrier signal to encode digital information in a telephone line

MODEM

42

Number of ships area assigned by the global maritime distress

4

43

Not required on board by the maritime distress

radio operator telegraphy on board

44

Efficiency of Class 4 MODEM

120%

45

frequency at which fiber optics operates

800THz

46

industrial noise frequency

15-160 MHz

47

what is optic window?

range of wavelength at which Fiber Optics operates

48

transmission lines are balance or unbalanced with respect to

ground

49

at 41.000 MHz to 41. 005 MHz and a channel capacity of 12.5kHz, what is the first center frequency

41.00625 MHz

50

wind loading of standard for Philippine antenna tower

200kph

51

energy that neither radiated into space nor completely transmitted

standing waves

52

Identifies the address of the webpage

uniform resource locator

53

electromagnetic radiation

James Clerk Maxwell

54

highest frequency wherein the signal is able to return back to earth

MUF

55

ISDN basic access line configuration

2B + D

56

FM and PM difference

lies in the different definitions of modulation index

57

1 erlang

1 TU

58

The minimum value of the occupied bandwidth sufficient to ensure the transmission of information at the rate and with the quality required for the system employed, under specified conditions

Necessary bandwidth

59

Electric field is perpendicular

TE

60

Electromagnetic wave having circular polarization means

electric field rotates

61

Reverberation time for large organs is ____ seconds

2

62

Camera output with no sync

noncomposite video

63

Bandwidth of AM

based on the highest component of the modulating signal

64

Advantage of PTM over PAM

much better noise immunity

65

In phase shift method, how many circuits is/are balanced

2

66

Frequency range of an aircraft’s VHF communications

118.000 MHz to 136.975 MHz (worldwide up to 151.975 MHz)

67

Detect signals that is both vertically and horizontally polarized simultaneously

Orthomode transducer

68

the reason why companding is employed in PCM is

protect small signals in PCM from quantizing distortion

69

the process that uses the orthogonality of sines and cosines that makes possible to transmit and receive to different signals simultaneously on the same carrier frequency

Quadrature multiplexing

70

unit of magnetic field strength

ampere/meter

71

the standard that specifies a balanced interference cable that will operate bit rates up to 10Mbps with a span distance of up to 1200m

RS-422A

72

when light strikes a flat polished end of a fiber, the fiber loss produced can be reduced by

antireflection coating

73

Total elapsed time for the instant of initial transmission to the reception of the echo in radar communication system

12.36microseconds

74

Used to collect RF signal in the receiver

antenna

75

Paging channel of a mobile communication network system

9.6, 4.8 kbps

76

Difference between synchronous and asynchronous transmission

the clocking is with the data of the synchronous transmission

77

local loop

two-wire or four-wire communication system that connects residences to central office premises

78

not describe a TV signal

spreading” of color is not always white (note: spreading is not the real term in the answer. sorry)

79

transfer rate when 101001 data is transferred at 6ms

1kbps

80

binary communication is better because

simpler, less costly, reliable

81

consideration of new entrant

technical, financial, legal

82

gain of 4 identically polarized antenna stacked one above the other

6dB over the gain of one antenna

83

when played in piano or other instruments, note similar to the pitch of 440 Hz is

note A above middle C

84

slow drift in frequency for self-excited transmitter oscillator circuit resulting to poor frequency stability

DC and RF heating of resistors then changes its values

85

slow drift in frequency for self-excited transmitter oscillator circuit resulting to poor frequency stability

Heating of capacitor in the oscillator

86

abrupt frequency variation of self-excited transmitter oscillator circuit resulting to poor frequency stability which changes frequency oscillation

loose connection of oscillator, amplifier and antenna

87

Electromagnetic wave below 5000 GHz being transmitted without artificial guide

hertzian wave

88

Propagation condition usually indicated when VHF signal is received from a station over 500 miles away

tropospheric ducting

89

Used to connect data link

bridging function

90

a fiber optic communication device consist of receiver transmitter used to clean up and amplify digital data moving from one place to another at opposite direction

optic regenerator

91

in sound energy, dominance of the first sound wave in any point of location has ____ effect

precedence

92

ratio of the level of modulated signal under the conditions of test modulated signal to the level of unmodulated signal without modulation

residual noise level

93

an entity, relying transmission, switching and local distribution facilities of local exchange and inter exchange carrier and overseas carriers providing enhanced services beyond provided by such carriers

value-added service provider

94

not a common application of microwave communication

mobile radio

95

___ is a character signifies the start of the test for Bisync

STX

96

Oscillator “leak through” of neutralized amplifier

back wave

97

In Ethernet, an 8-bit frame similar to that of a preamble which last two bits are 1s

start of frame delimiter

98

In data communications, the maximum variable-length transmission packet is 4096 bytes and the default is _____ bytes

128

99

Type of emission used for radio telegraph and sidebands on the carrier

Spark emission

100

Average power of a radio transmitter supplied at the transmission antenna

mean power

101

 

ionospheric scatter

Complete List of Communications Engineering Coaching Materials


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