You dont have javascript enabled! Please enable it! Communications Engineering Mastery Test 20: ECE Pre-Board

# Communications Engineering Mastery Test 20: ECE Pre-Board

This is 100 items Practice Examinations set 20 in Communications Engineering (Electronics Systems and Technology) composed of previous Board Exams Questions. Read each question and choice carefully! Choose the best answer. In the actual board, you have to answer 100 items in Communications Engineering within 5 hours. You have to get at least 70% to pass the subject. Communications Engineering is 30% of the total 100% Board Rating along with Mathematics (20%), General Engineering and Applied Sciences (20%), and Electronics Engineering (30%). Familiarize each and every question to increase the chance of passing the ECE Board Examination.

#### Start the Test Yourself Exam 20

Choose the letter of the best answer in each questions.

1) What is a period of a wave?

a) The number of degrees in one cycle

b) The number of zeros crossing in one cycle

c) The amplitude of a wave

d) The time required to complete one cycle

Solution:

2) Which of the following colors of light rays has the shortest wavelength?

a) yellow

b) violet

c) red

d) blue

Solution:

3) A device that connects two dissimilar networks and performs the protocol conversion.

a) gateway

b) coupler

c) transformer

d) converter

Solution:

4) A major and basic advantage for the use of klystron.

a) High power

b) Efficiency

c) Lesser noise

d) Cheaper

Solution:

5) A band where most military satellite often operate.

a) Ku

b) C

c) X

d) L

Solution:

6) The final power amplifier in an FM transmitter usually operates class

a) AB

b) C

c) B

d) A

Solution:

7) A radio land station in the land mobile service

a) Mobile station

b) Land station

c) Base station

d) Ship earth station

Solution:

8) Where do the maximum current and minimum voltage values on a resonant Hertz dipole exist?

a) Center of the antenna

b) Near the end of the antenna

c) Near the center of the antenna

d) Ends of the antenna

Solution:

9) How can the antenna efficiency of a HF grounded vertical antenna be made comparable to that of a half-wave antenna?

a) By lengthening the vertical

b) By shortening the vertical

c) By installing a good ground radial system

d) By isolating the coax shield from ground

Solution:

10) At what distance is VHF propagation normally limited?

a) Around 500 miles

b) Around 1500 miles

c) Around 2000 miles

d) Around 1000 miles

Solution:

11) What is meant by the term antenna efficiency?

a) Efficiency = (effective radiated power / transmitted output) x 100%

b) Efficiency = (radiation resistance / transmission resistance) x 100%

c) Efficiency = (total resistance / radiation resistance) x 100%

d) Efficiency = (radiation resistance / total resistance) x 100%

Solution:

12) This is referred to as a fixed radio station that broadcasts program material from studio to transmitter by radio link.

a) Aural BC intercity relay

b) Aural broadcast STL

c) Short-wave station

d) Remote-pickup

Solution:

13) In television broadcasting, vivid strong colors are often referred as

a) saturation

b) hue

c) chrominance

d) luminance

Solution:

14) Which of the following is designated as the international distress, safety and calling frequency for radio telephony for stations of the maritime mobile service when using frequencies in the authorized bands between 156 and 174 MHz?

a) 165.8 MHz

b) 156.8 MHz

c) 158.6 MHz

d) 168.5 MHz

Solution:

15) Best describe as an amplifier used in radio telephony?

a) Magnifier

b) Class B

c) Class C

d) Class A

Solution:

16) The use of the telecommunication for the transmission of signals to initiate, modify or terminate functions of equipment at a distance.

a) Tracking

b) Space command

c) Telecommand

d) Trunking

Solution:

17) Best describe as a dip-meter.

a) a field strength meter

b) an SWR meter

c) a counter

d) a variable LC oscillator with metered feedback current

Solution:

18) Refers to an emission designation for facsimile

a) J3E and F4E

b) A3J and A4E

c) A3C and F3C

d) R3E and A3E

Solution:

19) How does a SSB transmitter output power normally expressed?

a) Average power

b) Peak power

c) In terms of peak-to-peak power

d) In terms of peak envelope power

Solution:

20) An increase in the effective power radiated by an antenna in a certain desired direction at the expense of power radiated in other directions.

a) Antenna gain

b) Antenna back lobe ratio

c) Antenna total ratio

d) Antenna efficiency

Solution:

21) Designates the sensation of low or high in the sense of the base and treble.

a) SPL

b) Pitch

c) Frequency

d) Intensity

Solution:

22) Sound intensity is given as:

a) df / dP

b) dP / dA

c) dE / dP

d) dA / dP

Solution:

23) A method of expressing the amplitude of complex non-periodic signals such as speech.

a) volume

b) frequency

c) pitch

d) wavelength

Solution:

24) A large speaker having a large diameter (15 cm and above).

a) tweeter

b) triaxial speaker

c) coaxial speaker

d) woofer

Solution:

25) Another SEG function that allows a person to be superimposed on another scene.

a) special effect generator

b) chroma keying

c) wiper

d) visual effect

Solution:

26) A form of telecommunication for the transmission of transient images of fixed moving objects.

a) E-mail

b) Internet

c) Television

Solution:

27) A good example of a pilot tone system used in commercial frequency modulation stations.

a) FDM

b) Time division

c) Stereo multiplexing

d) Frequency modulation

Solution:

28) A convenient method of determining antenna impedance.

a) reactance circle

b) stub matching

c) Smith chart

d) Trial and error

Solution:

29) Unity gain antenna.

a) half-wave dipole

b) rhombic

c) dummy

d) isotropic

Solution:

30) A region in front of a parabolic antenna.

a) Transmission zone

b) All of these

c) Fraunhofer

d) Fresnel

Solution:

31) An antenna that can only receive a television signal.

a) Isotropic antenna

b) Reference antenna

c) TVRO

d) Yagi antenna

Solution:

32) Radiation pattern of a discone

a) figure of eight

b) bi-directional

c) omnidirectional

d) unidirectional

Solution:

33) Radio wave concentration in the direction of the signal emitted by a directional antenna.

a) Back lobe radiation

b) Transmitted signal

c) Side lobe radiation

d) Major lobe radiation

Solution:

34) The reflector and director of an antenna array are considered as:

a) Transcendental elements

b) Feed-points

c) Driver elements

d) Parasitic elements

Solution:

35) An electronic equipment used to measure standing wave ratio.

a) Altimeter

b) Multimeter

c) Reflectometer

d) Wavemeter

Solution:

36) The product of the power supplied to the antenna and its gain relative to a half-wave dipole in a given direction.

a) Rated power

b) ERP

c) Peak envelope power

d) Carrier power

Solution:

37) What makes an antenna physically long but electronically short?

a) Adding C in series

b) All of these

d) Adding L in series

Solution:

38) Gateway can interconnect LANs that have ______ protocols and formats.

a) the same

b) different or the same

c) totally different

d) none of these

Solution:

39) Steps to follow to produce PCM signal.

a) quantizing, sampling & coding

b) sampling, quantizing, & coding

c) sampling, coding, & quantizing

d) coding, quantizing, & coding

Solution:

40) Transmission sent in both directions simultaneously

a) Full duplex

b) Duplex

c) Half-duplex

d) Simplex

Solution:

41) ____ detects the satellite signal relayed from the feed and convers it to an electric current, amplifies and lower its frequency.

a) Feedhorn

b) Satellite dish

d) LNB

Solution:

42) What kind of battery panels is used in some advance satellites?

a) Gallium Arsenide solar panel

b) Germanium based panels

c) Silicon based panels

d) Gallium Phosphate solar panel

Solution:

43) Footprint refers to coverage area in the globe.

a) Satellite radiation polarization

c) Satellite radiation pattern

d) Satellite coverage

Solution:

44) AsiaSat I covers how many countries in Asia?

a) 38

b) 40

c) 44

d) 42

Solution:

45) Insertion loss of connector-type splices for a single-mode fiber cable.

a) 0.2 dB

b) 0.3 dB

c) 0.09 db

d) 0.38 dB

Solution:

46) A non-coherent light source for optical communications system.

a) PIN Diode

b) ILD

c) APD

d) LED

Solution:

47) Type of fiber that has the highest model dispersion.

a) Step-index multimode

b) Step-index single mode

c) Graded index mode

d) Graded index multimode

Solution:

48) What do you call of a sound transducer that uses a polarizing potential and depends upon capacitance variation for generation of a corresponding potential difference?

a) electrostatic

b) electroacoustic

c) electrodynamic

d) electromagnetic

Solution:

49) A special type of electrostatic microphone which holds polarization indefinitely without continued application of a polarizing potential.

a) condenser microphone

b) capacitive microphone

c) electret microphone

d) all of these

Solution:

50) Sound transducer whose output potential is generated through the flexing of crystalline elements as it is acted by sound waves.

a) piezoelectric

b) electroacoustic

c) electrodynamic

d) electromagnetic

Solution:

51) An electroacoustic transducer that radiates acoustic power into the air. The acoustic waveform is equivalent to the electrical input wave from.

a) electret

b) diaphragm

c) piezoelectric

d) loudspeaker

Solution:

52) Loudspeaker low frequencies response will be maximum if positioned in a room at the

a) wall center of the floor level

b) center of room

c) center of wall

d) corner

Solution:

53) Chromatic dispersion is due to the effect of

a) material dispersion

b) wavelength dispersion

c) Rayleigh distribution

d) A and b

Solution:

54) What wavelength is most commonly used for long distance, high capacity system?

a) 850 nm

b) 1300 nm

c) 1550 nm

d) any of these

Solution:

55) What wavelength has the minimum loss in optical fibers?

a) 850 nm

b) 1300 nm

c) 1550 nm

d) 1310 nm

Solution:

56) The easy way to avoid intermodal dispersion is to use

a) graded index fiber

b) plastic fiber

c) glass fiber

d) single mode fiber

Solution:

57) Intermodal dispersion may be overcome by using

a) coherent light source

b) highly sensitive detectives

c) step index fiber

d) graded index fiber

Solution:

58) A microcomputer attached to a network requires a _____.

a) dongle

b) network interface card

c) RS-232

d) Software

Solution:

59) To _____ is to send a file to a remote computer.

c) call

d) transmit

Solution:

60) ____ network topology has more than one level of host computer.

a) Star

b) Bus

c) Hierarchical

d) Ring

Solution:

61) It is the term that is used to describe the form or the shape of a network.

a) network model

b) network layer

c) network topology

d) network protocol

Solution:

62) The term _____ was devised by the telephone company to describe a specific type of equipment but today, it is used to describe a general carrier system, a date rate, and various framing conventions.

a) OSI System

b) T1 System

c) Digital Service Unit

d) Channel Service Unit

Solution:

63) It describes how terminals are connected logically by an international link while each terminal is operating within its own packet mode data network.

a) X.24

b) X.25

c) RS-232

d) X.75

Solution:

64) The connectionless-mode network service manages _____ as independent entities.

a) packets

b) routers

c) frames

d) token

Solution:

65) It is a widely used transport protocol which has the job to deliver and receive data across network boundaries.

a) Data Link Protocol

b) Transmission Control Protocol

c) Data Field

d) Control Field

Solution:

66) The _____ protocol provides the user interface to the Medium Access Control Sublayer.

a) Data Link Control

b) Logical Link Control

c) IEEE protocol 802.4

d) IEEE protocol 802.3

Solution:

67) It is the transmission of documents or graphics.

a) E-mail transmission

b) Facsimile transmission

c) Digital transmission

d) Analog transmission

Solution:

68) A network switching that creates a dedicated temporary connection between computers in a network.

a) Circuit switching

b) Message switching

c) Packet switching

d) Virtual switching

Solution:

69) A data network that is built and owned by a common carrier.

a) Public data network

b) Private data network

c) Leased line network

d) Node

Solution:

70) A data communications component that provides control or supporting services for other computers, terminals, or devices in a network.

a) Host

b) Communications controller

c) Cluster controller

d) Interface equipment

Solution:

71) A conceptual network in which all transmission lines handle digital or digitized data.

a) Local Area Network

b) Wide Area Network

c) Integrated Services Digital Network

d) Public Switch Telephone Network

Solution:

72) A device that provides a communication between logically or physically separated network.

a) Router

b) Hub

c) Bridge

d) Modem

Solution:

73) A radio system that uses digital multiplexing technology to increase the capacity of the special mobile radio channels.

a) Electronic Data System

b) Enhanced Radio Technology

c) Enhanced Special Mobile Radio

d) Electronic Mobile System

Solution:

74) A feature that permits a subscriber to dial a number by calling the number out to the cellular phone, instead of punching the numbers in the phone. This technology has been offered to several models of mobile phones which contribute to convenience as well as driving safety.

a) automatic dialing system

b) voice-activated dialing

c) automatic call system

d) voice-controlled system

Solution:

75) It is the commonly used cellular network that transmits voice and data over cellular channels using analog technology.

a) A system

b) B system

c) Circuit-switched

d) Amplitude Modulated System

Solution:

76) The amount of time the subscriber can leave the fully charges cellular portable or transportable phone turned on before the phone will completely discharge the batteries.

a) battery time

b) standby time

c) battery life

d) cellular time

Solution:

77) A process that provides security for wireless information. Information is encoded so that it can be read by a device with a matching decoding procedure.

a) wireless decoder

b) cellular decoder

c) encryption

d) decoder

Solution:

78) A measure of the probability that a call offered to a group of trunks or circuits will fail to find idle circuit at the first attempt.

a) busy hour

b) traffic quantity

c) grade of service

d) erlang

Solution:

79) The aggregate engagement time or occupancy time of one or more traffic paths.

a) busy hour

b) traffic quantity

c) grade of service

d) erlang

Solution:

80) Continuous hour period that has the maximum average traffic intensity.

a) busy hour

b) traffic quantity

c) grade of service

d) erlang

Solution:

81) What is the basic measurement of quality in PCM link?

a) slipping rate

b) bit error rate

c) S/N ratio

d) Average power

Solution:

82) The part of PCM signal which consist of a series of bit stream after quantizing and coding which contains a full sequence or cycle of PCM process.

a) pulse frame

b) period

d) data

Solution:

83) In AM, 100% modulation means an increase in total power by _____.

a) 25%

b) 75%

c) 100%

d) 50%

Solution:

84) Emission with only one sideband transmission

a) A3E

b) 3AJ

c) 11BE

d) H3E

Solution:

85) In radio emission designation, what letter in the in the first symbol represent a double-sideband type of modulation?

a) A

b) B

c) C

d) D

Solution:

86) In radio receivers, mixing process means?

a) interference elimination

b) The combination of two signals to produce sum and difference frequencies.

c) The elimination of noise in a wideband receiver by phase differentiation

d) The elimination of noise in a wideband receiver by phase comparison

Solution:

87) Emission F3F refers to

a) Facsimile

b) Modulated CW

c) RTTY

d) Television

Solution:

88) Sound intensity is given as:

a. dP/dA

b. dE/dP

c. df/dP

d. dP/dE

Solution:

89) Sounds we ordinarily hear have intensities in the range from about.

a. 10-6 to 10-16 W/m2

b. 10-5 to 10-16 W/m2

c. 10-8 to 10-1 W/m2

d. none of these

Solution:

90) A dome over a stadium has a diameter of 100 m and an area of 104 m2. If the average intensity of sound passing outward of through this surface is 10-3 W/m2, the total power is about

a. 20 W

b. 10 W

c. 30 W

d. 40 W

Solution:

91) Sound intensity level is given by: in dB:

a. 10 log I/Iref

b. 20 log I/Iref

c. 10 log Pref/Iref

d. 20 log Iref/Pref

Solution:

92) The reference intensity for sound in air is:

a. 10 โ 10 W/m2

b. 10 โ 12 W/m2

c. 10 โ 16 W/m2

d. 10 โ 13 W/m2

Solution:

93) The intensity of sound which is 10-3 W/m2 in dB

a. 90

b. 80

c. 70

d. 60

Solution:

94) Sound pressure level in dB is:

a. 20 log P/Pref

b. 10 log P/Pref

c. 10 log P/ref/P

d. 10 log I/Iref

Solution:

95) Pressure amplitude reference level of sound in air:

a. 20 millipascal

b. 20 micropascal

c. 30 micropascal

d. 40 micropascal

Solution:

96) A sound pressure amplitude level of 0.4 Pa corresponds to a sound pressure level in dB equal to:

a. 26

b. 40

c. 86

d. 56

Solution:

97) An SPL of 58 dB means:

a. 0.15 Pa

b. 0.016 Pa

c. 1.8 Pa

d. 2 Pa

Solution:

98) Absence of reception.

a. skip distance

b. maximum usable

d. twilight zone

Solution:

99) Each point on a spherical wavefront maybe a source of a secondary spherical wavefront.

a. Snellโs Law

b. Huygenโs Principle

c. Rayleighโs Principle

d. De Morganโs theorem

Solution:

100) Determine the field strength at 1 mile for a vertical antenna ยผ wavelengths high when power is 1 kw and antenna loop resistance is 8 ohms.

a. 0.4 V/m

b. 5 mV/m

c. 1 mV/m

d. 0.2 V/m

Solution:

### Complete List of Communications Engineering Exams: ECE Pre-Board

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