Saturday, December 13, 2014

Series of Communications Engineering Exams: ECE Pre-Board

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Communications Engineering Examinations

This is the list of 100 items set of Pre-board Exams in Communications Engineering (Electronics Systems and Technology) composed of previous Board Exams Questions and cautiously selected questions from various topics in Communications that could possibly be given in the board. Choose, familiarize, and test yourself so that you will know the taste of the Board Exam Questions. 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. Electronics Engineering is 30% of the total 100% Board Rating along with Mathematics (20%), General Engineering and Applied Sciences (20%) and Electronics Systems and Technology (30%).

Choose Communications Engineering Pre-Board Exams

Communications Engineering Pre-Board Exams
Module 1: Communications Engineering Exam 1                  Answer key: EXAM 1
Module 2: Communications Engineering Exam 2                  Answer key: EXAM 2
Module 3: Communications Engineering Exam 3                  Answer key: EXAM 3
Module 4: Communications Engineering Exam 4                  Answer key: EXAM 4
Module 5: Communications Engineering Exam 5                  Answer key: EXAM 5
Module 6: Communications Engineering Exam 6                  Answer key: EXAM 6
Module 7: Communications Engineering Exam 7                  Answer key: EXAM 7
Module 8: Communications Engineering Exam 8                  Answer key: EXAM 8
Module 9: Communications Engineering Exam 9                  Answer key: EXAM 9
Module 10: Communications Engineering Exam 10            Answer key: EXAM 10

Other Series of MCQs and Reviewers in Communications Engineering

You can also check the Series of Multiple Choice Questions in Communications Engineering per topic.


Published by: Froyd Wess23:08

Communications Engineering Exam 10: ECE Pre-Board - Answers

Communications Engineering Exam 10 - Answers

Below are the answers key for the 100 items set of Practice Examination 10 in Communications Engineering composed of previous Board Exams Questions and cautiously selected questions from various topics in Communications Engineering (Electronics Systems and Technology) that could possibly be given in the board.

1. WAP

2. Impulse noise

3. 0.38 db

4. 20%

5. 70 MHz

6. X modem

7. Spacing bias distortion

8. 317 W

9. GPRS

10. COW

11. A variable LC oscillator with metered feedback current

12. Two or more antennas operating on the same frequency

13. Video detector

14. 258

15. In the nonlinear region

16. 64 kbps

17. 3 kHz

18. 50 dB

19. R3E

20. 30 MHz

21. Cathode end of the helix

22. Antenna directivity

23. 14

24. A3J

25. Free space

26. Loudness

27. 15

28. Homing

29. The amount of radiation received from the sun

30. The noise floor of the receiver

31. 1000 Hz

32. Poor front-end selectivity

33. VHF

34. H bend

35. 1.25 MHz

36. Horizontal

37. Zone of silence

38. 20 %

39. STX

40. Wow

41. When 60% of the capital is owned by Filipino citizens

42. Logatom

43. Because their power is increased by class C amplifiers

44. 1361.25 W

45. ITU-W

46. Neutralization

47. PLL

48. Logical

49. 0.635 to 15.24 cm

50. 44.736 Mbps

51. Nature of multiplexing

52. 500 Hz

53. ITU-T

54. 2174.5 kHz

55. Power margin

56. Load water

57. Dark conductance

58. One upper sideband

59. Directional coupler

60. Optical media board

61. AB test

62. V series

63. T4

64. 40 dB

65. 96

66. Lambertian source

67. 30 to 53 kHz

68. 125,000

69. Fresnel reflection

70. World telecommunication standardization conference

71. Fringe area

72. Grass

73. Vertical Marconi antenna

74. The audio section

75. Mush

76. Waveguide switch

77. 10 W

78. Quad

79. Double-balanced

80. X-rays

81. Convergence

82. Department Order No. 5

83. Master

84. Marconi antenna

85. Discriminator

86. Character

87. Interpolator

88. 239 ms

89. 1 pW

90. Sunspot

91. Prominence

92. Filament

93. 10.7 cm band

94. 32,000 nT

95. 62,000 nT

96. Picosat

97. Sputnik 2

98. CDMA

99. 2.5G

100. Bluetooth

What's next in line?
  • Communications Engineering Exam 11: ECE Pre-Board

Complete List of Communications Engineering Exams: ECE Pre-Board


Published by: Froyd Wess16:07

Communications Engineering Exam 10: ECE Pre-Board

Filed under: ,

Communications Engineering Exam 10

This is 100 items set of Practice Examination 10 in Communications Engineering (Electronics Systems and Technology) composed of previous Board Exams Questions. Read each questions and choices 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 questions to increase the chance of passing the ECE Board Examination.

Start the Test Yourself Exam 10

1. ________ is a standard whereby mobile phones can gain access to specially tailored Internet websites.

  • A. Bluetooth
  • B. GPRS
  • C. WAP
  • D. EDGE

2. What noise is a transient short-duration disturbance distributed essentially uniformly over the useful passband of a transmission system?

  • A. Flicker noise
  • B. Transit-time noise
  • C. Shot noise
  • D. Impulse noise

3. What is the insertion loss of connector type splices for a single mode optical fiber?

  • A. 0.51 dB
  • B. 0.49 dB
  • C. 0.31 dB
  • D. 0.38 db

4. In the European standard, the aurial transmitter maximum radiated power is ______ of peak visual transmitter power.

  • A. 10%
  • B. 30%
  • C. 20%
  • D. 40%

5. What is the common up-converter and down-converter IF for microwave communications?

  • A. 60 MHz
  • B. 80 MHz
  • C. 120 MHz
  • D. 70 MHz

6. What is the data link protocol that is used in asynchronous transmission for transferring files from one computer to another?

  • A. A modem
  • B. X modem
  • C. B modem
  • D. C modem

7. What distortion is not caused by transmission line characteristics?

  • A. Phase distortion
  • B. Pulse shape distortion
  • C. Spacing bias distortion
  • D. Amplitude distortion

8. What is the effective radiated power of a repeater with 200 watts transmitter power output, 4 dB feline loss, 4 dB duplexer and circulator loss, and 10 dB antenna gain?

  • A. 317 W
  • B. 2000 W
  • C. 126 W
  • D. 260 W

9. Which of the following is standardized as part of GSM phase 2+ that can offer theoretical data speeds of up to 115 kbit/s?

  • A. EDGE
  • B. GPRS
  • C. WAP
  • D. Bluetooth

10. A ______ is essentially a cell site that is mounted on a flatbed tractor-trailer used for emergency purposes.

  • A. COW
  • B. BULL
  • C. CALF
  • D. PONY

11. Which of the following best describes a dip-meter?

  • A. An SWR meter
  • B. A counter
  • C. A variable LC oscillator with metered feedback current
  • D. A field strength meter

12. Which is space diversity system?

  • A. Two or more antennas operating on two different frequencies?
  • B. Two transmitters operating at same frequencies
  • C. Two or more antennas operating on the same frequency
  • D. Two antennas from two different transmitters

13. What part or section of a TV receiver that separates the sound and video signals?

  • A. IF stage
  • B. Video amplifier
  • C. Video detector
  • D. Burst separator

14. What is the channel number of an FM station with a carrier frequency of 99.5 MHz?

  • A. 256
  • B. 258
  • C. 257
  • D. 259

15. In a triple conversion superheterodyne receiver, diode mixer stages are operated

  • A. In the linear region
  • B. In the nonlinear region
  • C. As class A amplifiers
  • D. As class B amplifiers

16. In ISDN, what is the basic access B channel data rate?

  • A. 32 kbps
  • B. 64 kbps
  • C. 144 kbps
  • D. 16 kbps

17. What is the channel spacing for MF-HF voice frequencies?

  • A. 2.8 kHz
  • B. 500 Hz
  • C. 3.5 kHz
  • D. 3 kHz

18. What is the quantization signal-to-noise ratio if an 8-bit PCM code is used?

  • A. 40 dB
  • B. 50 dB
  • C. 60 dB
  • D. 65 dB

19. What is the emission designation of a single sideband reduced carrier signal?

  • A. H3E
  • B. J3E
  • C. R3E
  • D. B8E

20. What is the most commonly used intermediate frequency of radar receivers?

  • A. 40 MHz
  • B. 60 MHz
  • C. 70 MHz
  • D. 30 MHz

21. The input signal of a travelling wave tube is introduced at

  • A. Cathode
  • B. Anode
  • C. Cathode end of the helix
  • D. Collector end of the helix

22. What determines the ability of radar to determine the bearing to a target?

  • A. Speed of light
  • B. Speed of target
  • C. Antenna directivity
  • D. Frequency of signal

23. What is the minimum number of bits required in a PCM code for a range of 10,000?

  • A. 12
  • B. 9
  • C. 14
  • D. 10

24. The antenna current is doubled when the modulation index is doubled in ______ AM system.

  • A. A5C
  • B. A3J
  • C. A3
  • D. A3H

25. Which of the following is not a bounded medium?

  • A. Coaxial line
  • B. Two-wire line
  • C. Waveguide
  • D. Free space

26. What is affected by the distance between the listener and the source of the sound because the intensity varies inversely with the square of the distance?

  • A. Volume
  • B. Pitch
  • C. Loudness
  • D. Frequency

27. Comparing the capacities of a DVD and an ordinary CD, DVD is ______ time bigger than CD.

  • A. 10
  • B. 20
  • C. 15
  • D. 25

28. Locking on to a defined target is known as

  • A. Homing
  • B. Referencing
  • C. Searching
  • D. Defining

29. What causes the maximum usable frequency to vary?

  • A. The temperature of the ionosphere
  • B. The speed of the winds in the upper atmosphere
  • C. The type of weather just below the ionosphere
  • D. The amount of radiation received from the sun

30. What limits the sensitivity of a receiver?

  • A. The power supply of the receiver
  • B. The power output of a transmitter
  • C. The noise floor of the receiver
  • D. The distance between the transmitter and receiver

31. What is the standard test tone used for audio measurements?

  • A. 100 Hz
  • B. 500 Hz
  • C. 1000 Hz
  • D. 2000 Hz

32. What causes image interference?

  • A. Low gain
  • B. High IF
  • C. Poor front-end selectivity
  • D. Low signal-to-noise ratio

33. What frequency band is referred to as the metric waves?

  • A. VHF
  • B. UHF
  • C. HF
  • D. SHF

34. A waveguide passive component that brings a smooth change in the direction of axis maintained perpendicular to the plane of polarization?

  • A. L bend
  • B. H bend
  • C. T bend
  • D. X bend

35. How far is the visual carrier from the lowest frequency in the spectrum of a monochrome TV broadcast channel following the NTSC standard?

  • A. 1.5 MHz
  • B. 1.25 MHz
  • C. 4.5 MHz
  • D. 0.25 MHz

36. What aircraft deviation is measured by an ILS localizer?

  • A. Altitude
  • B. Ground speed
  • C. Vertical
  • D. Horizontal

37. Skip zone is otherwise known as

  • A. Empty zone
  • B. Shadow zone
  • C. Null zone
  • D. Zone of silence

38. In the American standard, the aural transmitter maximum radiated power is _____ of peak visual transmitter power.

  • A. 10 %
  • B. 30 %
  • C. 20 %
  • D. 40 %

39. What character signifies the start of the test for Bisync?

  • A. STX
  • B. SOH
  • C. BCC
  • D. ETX

40. A low frequency audible periodic variation in pitch of sound output in high fidelity sound reproduction system?

  • A. Flutter
  • B. Wow
  • C. String vibration
  • D. Radio sound

41. When can a corporation or association incorporated under the Philippine laws and with foreign investors be granted radio station license?

  • A. When 60% of the capital is owned by Filipino citizens
  • B. When 50% of the capital is owned by Filipino citizens
  • C. When the chairman of the board is a Filipino
  • D. When the president of the corporation/association is a Filipino

42. ______ is a term in the test language for noise testing in telephone circuits that means a one-syllable word consisting of a consonant, a vowel, and another consonant.

  • A. Logatom
  • B. Nosfer
  • C. Ore
  • D. Belcore

43. Why are frequency modulation transmitters more efficient?

  • A. Because their power is increased by class C amplifiers
  • B. Because their power is increased by class A amplifiers
  • C. Because their power is increased by class B amplifiers
  • D. Because their power is increased by class AB amplifiers

44. A 1000W carrier is amplitude modulated to a depth of 85%. Calculate the total power of the modulated wave?

  • A. 1361.25 W
  • B. 680.62 W
  • C. 1425 W
  • D. 712.5 W

45. Which is not an ITU sector?

  • A. ITU-W
  • B. ITU-R
  • C. ITU-T
  • D. ITU-D

46. What is the process of cancelling the effect on internal device capacitance in radio transmitters?

  • A. Degaussing
  • B. Neutralization
  • C. Ionization
  • D. Stabilization

47. Which of the following is the basic synthesizer circuit?

  • A. Frequency divider
  • B. Frequency multiplier
  • C. PLL
  • D. Mixer

48. Which one is not an important characteristic of the physical layer?

  • A. Electrical
  • B. Logical
  • C. Mechanical
  • D. All of the choices

49. What is the typical separation between the two conductors in a parallel wire line?

  • A. 0.001 to 0.01 m
  • B. 200 to 500 mm
  • C. 0.635 to 15.24 cm
  • D. 2.5 to 5 in.

50. In t-carrier system, t3 has a bit rate of

  • A. 560.160 Mbps
  • B. 44.376 Mbps
  • C. 44.736 Mbps
  • D. 560.106 Mbps

51. In radio signal emission designation, the fifth symbol means

  • A. Details of signals
  • B. Type of information transmitted
  • C. Nature of multiplexing
  • D. Nature of signal modulating the main carrier

52. What is the channel spacing for SITOR frequencies?

  • A. 500 Hz
  • B. 170 Hz
  • C. 300 Hz
  • D. 3 kHz

53. Which of the following is the new name of CCITT?

  • A. ITU-T
  • B. ITU-R
  • C. ITU-S
  • D. ITU-D

54. Which of the following frequencies is normally used for distress and safety communications?

  • A. 4209.5 kHz
  • B. 490 kHz
  • C. 518 kHz
  • D. 2174.5 kHz

55. What is the difference between available power and power budget?

  • A. Power margin
  • B. Extra power
  • C. Fade margin
  • D. System gain

56. A matched termination in which the electromagnetic energy is absorbed by water.

  • A. Maximum power transfer
  • B. Load
  • C. Load water
  • D. Basin

57. What do you call the electrical conduction in a photosensitive material which is not exposed to radiation?

  • A. Dark conductance
  • B. Pure conductance
  • C. Black out
  • D. Super conductance

58. How many sidebands are present in the J3E mode?

  • A. Two sidebands and a carrier
  • B. One upper sideband
  • C. One lower sideband
  • D. Two carriers and one sideband

59. A component that samples the microwave signal travelling in one direction down to the transmission line

  • A. Isolator
  • B. Combiner
  • C. Directional coupler
  • D. Attenuator

60. What does OMB stand for?

  • A. Optical media board
  • B. Organization of medical biologist
  • C. Optical medium board
  • D. Optimum main board

61. A test method of comparing two audio systems by switching inputs so that the same recording is heard in rapid succession over one given system and then the other.

  • A. B test
  • B. A test
  • C. AB test
  • D. C test

62. And ITU-T specification code that deals with the telephone circuits.

  • A. X series
  • B. T series
  • C. V series
  • D. I series

63. What digital carrier transmits a digital signal at 274.176 Mbps?

  • A. T1
  • B. T3
  • C. T2
  • D. T4

64. What signal-to-noise ratio is required for satisfactory television reception?

  • A. 10 dB
  • B. 30 dB
  • C. 40 dB
  • D. 20 dB

65. How many telephone channels are there in AT 2 line?

  • A. 50
  • B. 90
  • C. 83
  • D. 96

66. What optical source radiates light uniformly in all directions?

  • A. Isotropic source
  • B. Lambertian source
  • C. Voltage source
  • D. Ideal source

67. What is the spectrum of stereophonic FM signal?

  • A. 19 to 38 kHz
  • B. 30 to 53 kHz
  • C. 59.5 to 74.5 kHz
  • D. 88 to 108 MHz

68. What is the required quality factor for an SSB filter with the following data: center frequency = 1 MHz, the desired attenuation level of the unwanted sideband = 80 dB and the separation between sidebands = 200 Hz?

  • A. 1,250
  • B. 12,500
  • C. 125,000
  • D. 25,000

69. What do you call the reflection of a part of incident light at the interface of two media that have different refractive indices?

  • A. Snell’s reflection
  • B. Fresnel reflection
  • C. Lambertian reflection
  • D. Huygen’s reflection

70. Which conference in the ITU-structure does the telecommunication standardization bureau report?

  • A. World telecommunication standardization conference
  • B. ITU-development sector
  • C. Radio regulation board
  • D. The secretary general

71. What region around a broadcasting transmitter in which satisfactory reception of broadcasting signal is not obtained?

  • A. Fringe area
  • B. Primary are
  • C. Secondary area
  • D. Tertiary area

72. What do you call the random noise seen on radar display screen?

  • A. Impulse noise
  • B. Atmospheric noise
  • C. Grass
  • D. Johnson noise

73. Which of the following antennas receives signals equally well from all directions in a horizontal plane?

  • A. Hetz antenna
  • B. Vertical Marconi antenna
  • C. Yagi antenna
  • D. Helical antenna

74. Where is the brightness control located in a TV?

  • A. The audio section
  • B. The video section
  • C. The grid-cathode circuit
  • D. The front panel

75. What is the term used in telephony and telegraphy for irregular disturbing radiation due to various causes and in a particular produced by arc transmitters causing a rushing sound in receiving telephones?

  • A. Fax tone
  • B. Mush
  • C. Hiss
  • D. Crosstalk

76. What device in a waveguide system used for stopping or diverting electromagnetic wave as desired?

  • A. Mechanical switch
  • B. Electric switch
  • C. Push-button switch
  • D. Waveguide switch

77. What is the maximum power that can be obtained from a microwave tube at 10 GHz?

  • A. 500 W
  • B. 10 W
  • C. 50 W
  • D. 20 W

78. What do you call a cable consisting of twisted pairs of conductors, each separately insulated?

  • A. Microstrip line
  • B. Strip line
  • C. Quad
  • D. Coaxial cable

79. What mixer type has the lowest spurious signals?

  • A. Double-balanced
  • B. Single-balanced
  • C. Super-heterodyner
  • D. Heterodyner

80. What are the electromagnetic radiations of wavelengths less than 300 angstroms?

  • A. X-rays
  • B. Ultraviolet rays
  • C. Infrared
  • D. Microwaves

81. What is known as the alignment of the three color guns to a common point?

  • A. Confetti
  • B. Divergence
  • C. Convergence
  • D. Synchronization

82. What is the department order that governs commercial radio operator?

  • A. Department Order No. 5
  • B. Department Order No. 23
  • C. Department Order No. 88
  • D. Department Order No. 44

83. The computer which initiates information transfer

  • A. Master
  • B. Station
  • C. Slave
  • D. Mainframe

84. Which of the following antennas require good grounding?

  • A. Yagi antenna
  • B. Hertz antenna
  • C. Marconi antenna
  • D. Isotropic antenna

85. Which circuit detects frequency modulated signal?

  • A. Modulator
  • B. Discriminator
  • C. Demodulator
  • D. Modem

86. What synchronization is provided so that the start and end of message is identified?

  • A. Carrier
  • B. Character
  • C. Bit
  • D. Clock

87. A form of regenerative repeater for transmitting signals over a long cable received through a relay in a clearer form.

  • A. Active generator
  • B. Active repeater
  • C. Interpolator
  • D. Audio generator

88. What is the minimum propagation delay of a geostationary satellite?

  • A. 278 ms
  • B. 239 ms
  • C. 300 ms
  • D. 600 ms

89. In measuring crosstalk using dBx unit the reference power is

  • A. 1 mW
  • B. 1 W
  • C. 1 pW
  • D. 6 mW

90. A spot on the sun’s visible surface where the magnetic flux lines converge?

  • A. Sunspot
  • B. Filament
  • C. Solar spot
  • D. Prominence

91. ______ is a slow moving large mass of plasma on the sun’s surface.

  • A. Filament
  • B. Solar flare
  • C. Prominence
  • D. Proton flare

92. ______ is slow moving “cord-like” mass of plasma across the sun’s surface.

  • A. Filament
  • B. Solar flare
  • C. Prominence
  • D. Solar spot

93. At what particular wavelength is solar flux measured?

  • A. 10.7 mm band
  • B. 10.7 m band
  • C. 10.7 cm band
  • D. 10.7 nm band

94. What is the approximate intensity of the magnetic field at the earth’s surface?

  • A. 32,000 nT
  • B. 62,000 nT
  • C. 32,000 µT
  • D. 62,000 µT

95. What is the intensity of the magnetic field at the earth’s north pole?

  • A. 32,000 nT
  • B. 62,000 nT
  • C. 32,000 µT
  • D. 62,000 µT

96. What do you call a satellite weighing less than 1 kg?

  • A. Nanosat
  • B. Picosat
  • C. Femtosat
  • D. Microsat

97. The first creature in space was carried by which of the following spacecrafts in November 3, 1957?

  • A. Sputnik 1
  • B. Sputnik 3
  • C. Sputnik 2
  • D. Explorer 1

98. The wireless evolution is achieved through the GSM family of wireless technology platforms which include but except one of the following. Which one is NOT a member of the GSM family?

  • A. GSM
  • B. EDGE
  • C. GPRS
  • D. CDMA

99. Which of the following is an enhancement of GSM including the GPRS?

  • A. 1G
  • B. 2.5G
  • C. 2G
  • D. 3G

100. A low power, short range wireless technology designed to provide a replacement for serial cables is called ______.

  • A. WAP
  • B. GPRS
  • C. Bluetooth
  • D. EDGE

Complete List of Communications Engineering Exams: ECE Pre-Board

Check your work.


Published by: Froyd Wess16:05

Communications Engineering Exam 9: ECE Pre-Board - Answers

Communications Engineering Exam 9 - Answers

Below are the answers key for the 100 items set of Practice Examination 9 in Communications Engineering composed of previous Board Exams Questions and cautiously selected questions from various topics in Communications Engineering (Electronics Systems and Technology) that could possibly be given in the board.

1. Timbre

2. 3300 m/s

3. 20 phons

4. 2λ to 8λ

5. 3100 kHz

6. 800

7. Effective Isotropic Radiated Power (EIRP)

8. Effective Radiated Power (ERP)

9. Gain-to-Equivalent Noise Temperature Ratio (G/Te)

10. Space noise

11. Hoghorn

12. 24

13. Space Division Multiplexing (SDM)

14. T2 carrier system

15. Metric

16. Spin stabilization

17. Membrane absorber

18. Syncom III

19. Calculate load admittance

20. A specially configured coaxial transmission line

21. Emission

22. 1887

23. Attenuation of radio wave

24. A parallel LC circuit

25. Courier

26. RA 9292

27. The President

28. 5

29. Within 15 days

30. 1

31. All of the choices

32. Solid

33. 1

34. Both A and C above

35. A 125-μs frame

36. L carrier

37. 564 – 3084 kHz

38. Dual polarization

39. 39.2 dB

40. 1.09

41. 275 ms

42. 0.5 s

43. 128

44. 5.4 MHz

45. 0.871 μW

46. 4 MHz

47. 4130 km

48. F2 layer

49. 47

50. 1.6 octaves

51. 3 times

52. 44.736

53. 358

54. Superrefraction

55. Temperature inversion

56. Duct

57. 1.35 cm and 1.7 mm

58. 5 mm and 2.5 mm

59. Ionosonde

60. 1100 km

61. 11.53 m/s

62. 343 m/s

63. 120 Hz

64. 320 kHz

65. D

66. Refraction

67. Using the smallest possible radiation angle and highest possible frequency

68. 32 km

69. 3853 Hz

70. NTT

71. 0.704 fF

72. Transponder

73. 35.3

74. Critical frequency

75. Frequency response

76. water vapor and oxygen

77. either elliptical or circular

78. Employment of highly directional spot-beam antennas

79. footprint

80. 440 Hz

81. 435

82. lower

83. 39.7 W

84. IS-95

85. 31.5 W

86. 10 Base T

87. 150 W

88. PD 576-A

89. 37.6 W

90. 13 kbps

91. 126 W

92. MC No. 2-05-88

93. 60 W

94. Hash

95. Twisted pair

96. EDGE

97. 12:00 Midnight to 5:00 AM

98. public-key encryption

99. 8 kbps

100. 7:8

What's next in line?

Complete List of Communications Engineering Exams: ECE Pre-Board


Published by: Froyd Wess15:23

Communications Engineering Exam 9: ECE Pre-Board

Filed under: ,

Communications Engineering Exam 9

This is 100 items set of Practice Examination 9 in Communications Engineering (Electronics Systems and Technology) composed of previous Board Exams Questions. Read each questions and choices 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 questions to increase the chance of passing the ECE Board Examination.

Start the Test Yourself Exam 9

1. What significant element of sound refers to its characteristic tonal quality?

  • A. Pitch
  • B. Tempo
  • C. Rhythm
  • D. Timbre

2. What is the velocity of sound in wood?

  • A. 5800 m/s
  • B. 5000 m/s
  • C. 3300 m/s
  • D. 3700 m/s

3. What is the typical loudness level of a watch ticking?

  • A. 0 phon
  • B. 40 phons
  • C. 20 phons
  • D. 60 phons

4. The typical length of the rhombic antenna is ____.

  • A. 2λ to 8λ
  • B. 10λ to 20λ
  • C. 1λ to 3λ
  • D. 5λ to 10λ

5. What is the carrier frequency of supergroup 10?

  • A. 2724 kHz
  • B. 2356 kHz
  • C. 2108 kHz
  • D. 3100 kHz

6. In SPADE system, how many PCM-encoded voice band channels are there?

  • A. 800
  • B. 600
  • C. 300
  • D. 240

7. The product of the radiated RF power of a transmitter and the gain of the antenna system in a given direction relative to an isotropic radiator is called ____.

  • A. Effective Radiated Power (ERP)
  • B. Effective Isotropic Radiated Power (EIRP)
  • C. Radiated Power
  • D. Transmit Power

8. The product of antenna input power and the antenna power gain expressed in kW is called __.

  • A. Effective Radiated Power (ERP)
  • B. Effective Isotropic Radiated Power (EIRP)
  • C. Radiated Power
  • D. Transmit Power

9. What satellite system parameter represents the quality of a satellite or an earth station receiver?

  • A. Gain-to-Equivalent Noise Temperature Ratio (G/Te)
  • B. Energy of Bit-to-Noise Density Ratio (Eb/No)
  • C. Carrier-to-Noise Density Ratio (C/No)
  • D. Bit energy

10. What noise is observable at frequencies in the range from about 8 MHz to somewhat 1.5 GHz?

  • A. Industrial noise
  • B. Atmospheric noise
  • C. Space noise
  • D. Shot noise

11. A special horn antenna consisting of a parabolic cylinder joined to a pyramidal horn.

  • A. Hoghorn
  • B. Cass-horn
  • C. Pyramidal horn
  • D. Conical horn

12. How many telegraph channels are there in the basic voice band channels?

  • A. 24
  • B. 96
  • C. 48
  • D. 672

13. Which of the following is oldest multiplexing scheme?

  • A. Frequency Division Multiplexing (FDM)
  • B. Time Division Multiplexing (TDM)
  • C. Code Division Multiplexing (CDM)
  • D. Space Division Multiplexing (SDM)

14. What carrier system multiplexes 96 voice band channels into a single 6.312 Mbps data signal?

  • A. T1 carrier system
  • B. T2 carrier system
  • C. T1C carrier system
  • D. T3 carrier system

15. What is the metric subdivision of VHF band?

  • A. Metric
  • B. Millimetric
  • C. Decimetric
  • D. Centimetric

16. In satellite communications, what means of attitude control is using the angular momentum of the spinning body to provide the roll and yaw stabilization?

  • A. Spin stabilization
  • B. Radial stabilization
  • C. Three-axis stabilization
  • D. Station keeping

17. Which of the following is NOT a porous absorber?

  • A. Prefabricated tiles
  • B. Plasters and spray on materials
  • C. Acoustic blankets
  • D. Membrane absorber

18. What historical satellite broadcasted live the 1964 Olympic games from Tokyo, Japan for the first time?

  • A. Syncom I
  • B. Syncom III
  • C. Syncom II
  • D. Syncom IV

19. In transmission line, which of the following is the first step in the procedure of using stub matching?

  • A. Calculate stub susceptance.
  • B. Calculate load admittance
  • C. Connect stub to load
  • D. Transform conductance to resistance

20. What type of balun (balanced-to-unbalanced) is used in high frequency applications?

  • A. Transformer type balun
  • B. A specially configured coaxial transmission line
  • C. A specially configured parallel-wire line
  • D. A λ/2 transformer balun

21. ____ is defined as any radiation of energy by means of electromagnetic wave.

  • A. Emission
  • B. Radiation
  • C. Radio
  • D. Broadcasting

22. In what year did Hertz discover radio waves?

  • A. 1844
  • B. 1873
  • C. 1887
  • D. 1895

23. Which of the following phenomena is possible is free space medium?

  • A. Reflection of radio wave
  • B. Diffraction of radio wave
  • C. Refraction of radio wave
  • D. Attenuation of radio wave

24. What is the reactance property at the input of a shorted quarter wavelength line?

  • A. A parallel LC circuit
  • B. A pure inductive reactance
  • C. A series LC circuit
  • D. A pure capacitive reactance

25. An early satellite owned by US Department of Defense that lasted only for 17 days

  • A. Courier
  • B. Echo
  • C. Score
  • D. Westar 1

26. Which of the following is the consolidation of H. No. 5224 and S. No. 2683?

  • A. RA 9292
  • B. RA 5734
  • C. RA 7925
  • D. RA 6849

27. Who will appoint the chairman and 2 members of the board of Electronics Engineering?

  • A. The Senate President
  • B. The President
  • C. The Supreme Court
  • D. The Commission on Appointment

28. How many nominees per position of the Electronics Engineering Board are nominated by IECEP to PRC?

  • A. 3
  • B. 5
  • C. 4
  • D. 6

29. According to RA 9292, how many days after the board exam the results will be released?

  • A. Within 5 days
  • B. Within 15 days
  • C. Within 20 days
  • D. Within 3 days

30. How many removal examination (s) will be given to an examinee who obtains a passing rating in the majority of the subjects but obtains a rating in the other subject (s) below seventy percent (70%) but not lower than sixty percent (60%)?

  • A. 1
  • B. 3
  • C. 2
  • D. Unlimited

31. Which of the following determines the acoustic behavior of gases?

  • A. Density
  • B. Pressure
  • C. Temperature
  • D. All of the choices

32. In what medium sound travels the faster?

  • A. Vacuum
  • B. Solid
  • C. Liquid
  • D. Gas

33. For a loudness level between 110 and 120 dB, the maximum daily exposure limit is ____ minute (s).

  • A. 1
  • B. 60
  • C. 20
  • D. 45

34. A porous material is far more efficient at high than low frequency absorption. How to improve sound absorption at lower frequencies using this absorber?

  • A. Increase the thickness
  • B. Decrease the thickness
  • C. Mount with and airspace behind
  • D. Both A and C above

35. Which of the following describes a TDM frame?

  • A. A 250-μs frame
  • B. A 125-μs frame
  • C. A 500-μs frame
  • D. A 60-μs frame

36. ____ system transmits frequency-division-multiplexed voice band signals over a coaxial cable for distances up to 4000 miles.

  • A. T carrier
  • B. X carrier
  • C. L carrier
  • D. F carrier

37. What is the spectrum range of U600 mastergroup?

  • A. 60 – 108 kHz
  • B. 564 – 3084 kHz
  • C. 312 – 552 kHz
  • D. 60 -2788 kHz

38. Which frequency reuse method is less effective because of Faraday’s effect?

  • A. Dual polarization
  • B. Reducing antenna beamwidth
  • C. Zonal rotation
  • D. Spin stabilization

39. Three telephone circuits, each having an S/N ratio of 44 dB, are connected in tandem. What is the overall S/N ratio?

  • A. 44 dB
  • B. 39.2 dB
  • C. 41 dB
  • D. 43.52 dB

40. What is the noise factor if the equivalent noise temperature is 25 K?

  • A. 1.09
  • B. 0.09
  • C. 0.36 dBm
  • D. 0.36

41. A ground station is operating to a geostationary satellite at a 5° angle of elevation. Calculate the round-trip time between ground station and satellite.

  • A. 275 s
  • B. 275 ms
  • C. 137.5 s
  • D. 137.5 ms

42. Calculate the reverberation time of a living room 8 ft high, 13 ft wide and 20 ft long. The total absorption of the building structure inside the room is 180.7 sabines with four persons present in the room.

  • A. 0.5 ms
  • B. 0.05 s
  • C. 0.5 s
  • D. 5 ms

43. What is the number of levels required in a PCM system with S/N ratio of 40 dB?

  • A. 64
  • B. 128
  • C. 256
  • D. 512

44. A radio communications link is to be established via the ionosphere. The maximum virtual height of the layer is 100 km at the midpoint of the path and the critical frequency is 2 MHz. The distance between stations is 600 km. determine the optimum working frequency?

  • A. 6.32 MHz
  • B. 2.1 MHz
  • C. 5.4 MHz
  • D. 1.8 MHz

45. Part of a microwave link can be approximated by free space conditions. The antenna gain are each 40 dB, the frequency is 10 GHz, and the path length is 80 km. Calculate the receive power for a transmitted power of 10 W?

  • A. 0.871 μW
  • B. 871 μW
  • C. 0.871 mW
  • D. 871 nW

46. What is the approximate critical frequency of the E layer?

  • A. 4 MHz
  • B. 5 MHz
  • C. 6 MHz
  • D. 3 MHz

47. What is the approximate single-hop nighttime range of F2 layer?

  • A. 3840 km
  • B. 3000 km
  • C. 4130 km
  • D. 2350 km

48. What ionospheric layer has a daytime approximate critical frequency of 8 MHz?

  • A. F2 layer
  • B. F1 layer
  • C. E layer
  • D. D layer

49. Determine the additional absorption (sabines) contributed by 10 persons in a room.

  • A. 47
  • B. 4.7
  • C. 0.47
  • D. 470

50. A frequency of 3000 Hz has how many octaves above 1000 Hz?

  • A. 1.6 octaves
  • B. 2.1 octaves
  • C. 1 octave
  • D. 3 octaves

51. The loudness level increased from 40 to 56 phons. What is the increase in loudness sensation?

  • A. 3 times
  • B. 4.5 times
  • C. 2 times
  • D. 4 times

52. In the North American TDM system, what is the transmission rate in Mbps of T3 carrier system?

  • A. 44.736
  • B. 6.312
  • C. 3.152
  • D. 274.176

53. What is the data rate in Mbps of a single satellite transponder considering an S/N of 30 dB?

  • A. 35.8
  • B. 3.58
  • C. 358
  • D. 3580

54. What condition occur when the refractive index of the air decreases with height much more rapidly the normal?

  • A. Refraction
  • B. Superrefraction
  • C. Subrefraction
  • D. Diffraction

55. What do you call the increase of temperature with height?

  • A. Temperature inversion
  • B. Normal inversion
  • C. Ducting
  • D. Superrefraction

56. ____ is a term given to the region where superrefraction occurs.

  • A. Strata
  • B. Duct
  • C. Isothermal region
  • D. Tropospheric region

57. Which of the following wavelengths where absorption of electromagnetic waves becomes peak due to vibrational resonances in the water vapor molecule?

  • A. 1.35 cm and 1.7 mm
  • B. 1.5 mm and 5 mm
  • C. 1.35 dm and 1.7 cm
  • D. 1.5 cm and 5mm

58. Oxygen molecule absorption peaks to electromagnetic wave are at what wavelengths?

  • A. 1.35 cm and 1.7 mm
  • B. 5 mm and 2.5 mm
  • C. 5 cm and 2.5 cm
  • D. 1.35 mm and 1.7 μm

59. What instrument normally measures the virtual height of ionosphere?

  • A. Ionosonde
  • B. Altimeter
  • C. Field meter
  • D. Radar

60. The angle of elevation of the antenna beam is 20°. Calculate the transmission-path distance for an ionospheric transmission that utilizes a layer of virtual height 200 km. Use flat-earth approximation.

  • A. 966 km
  • B. 2100 km
  • C. 1100 km
  • D. 405 km

61. If temperature change is 19°C, what amount of change to sound velocity is possible?

  • A. 11.53 ft/s
  • B. 11.53 m/s
  • C. 19.304 ft/s
  • D. 19.304 m/s

62. In the above problem, what is the new velocity of sound assuming dry air medium?

  • A. 343 ft/s
  • B. 3430 m/s
  • C. 343 m/s
  • D. 342 m/s

63. In acoustics, if the volume of the room is 200 m3 then at what frequency the coefficient of absorption is measured?

  • A. 120 kHz
  • B. 120 Hz
  • C. 100 Hz
  • D. 150 Hz

64. What is the approximate bandwidth of an FM system with 10 kHz of modulating frequency and a 150 kHz of frequency deviation?

  • A. 300 kHz
  • B. 320 kHz
  • C. 150 kHz
  • D. 200 kHz

65. Which of the following layers of the ionosphere has no effect on sky wave propagation during daytime?

  • A. D
  • B. E
  • C. F1
  • D. F2

66. What phenomenon causes the radio-path horizon distance to exceed the geometric horizon?

  • A. Diffraction
  • B. Ducting
  • C. Reflection
  • D. Refraction

67. How to maximize the skip distance?

  • A. Using the smallest possible radiation angle and highest possible frequency
  • B. Using the smallest possible radiation angle and lowest possible frequency
  • C. Using the biggest possible radiation angle and highest possible frequency
  • D. Using the biggest possible radiation angle and lowest possible frequency

68. For a space wave transmission, the radio horizon distance of a receiving antenna with a height of 64 meters is approximately

  • A. 8 km
  • B. 32 km
  • C. 64 km
  • D. 256 km

69. What bandwidth is needed to support a capacity of 128 kbps when the signal power to noise power ratio in decibels is 100?

  • A. 19224 Hz
  • B. 3853 Hz
  • C. 19244 Hz
  • D. 3583 Hz

70. Which of the following systems uses frequency band 870-885 MHz as a transmit band of its base station?

  • A. TACS
  • B. NTT
  • C. NMT
  • D. AMPS

71. A transmitted signal 5 meters in wavelength is received by an antenna coil having a 50-Ω resistance and a 0.01 H inductance. What is the capacitance of the tuner shunting the antenna coil at this point?

  • A. 0.704 fF
  • B. 0.704 μF
  • C. 0.704 nF
  • D. 0.704 mF

72. Which of the following is the basic component of a communications satellite receiver?

  • A. On-board computer
  • B. Reflector
  • C. Telemetry
  • D. Transponder

73. The reverberation time of a 184.2 cubic meters broadcast studio is 0.84 sec. Find the absorption effect of the materials used in metric sabines.

  • A. 35.3
  • B. 10.96
  • C. 379.8
  • D. 109.6

74. What is the highest frequency that can be sent straight upward and be returned to earth?

  • A. MUF
  • B. Gyro frequency
  • C. Skip frequency
  • D. Critical frequency

75. What is the most important specification of loudspeakers and microphones?

  • A. Frequency response
  • B. Power density
  • C. Field Strength
  • D. Gain

76. Atmospheric attenuation is an attenuation which is due to

  • A. mist and fog
  • B. gasses in the atmosphere
  • C. water vapor and oxygen
  • D. rain

77. Satellite orbits around the earth are ____ orbits.

  • A. circular
  • B. either elliptical or circular
  • C. elliptical
  • D. circular only

78. How does spatial isolation technique in satellite communications avoid interference?

  • A. Use of different polarity antennas
  • B. Use of different types of antennas
  • C. Employment of highly directional spot-beam antennas
  • D. Use of low gain antennas

79. An area on earth covered by a satellite radio beam is called ____.

  • A. SSP
  • B. Region
  • C. footprint
  • D. primary area

80. The American concert pitch A is equivalent to which if the following frequencies?

  • A. 440 Hz
  • B. 435 Hz
  • C. 260 Hz
  • D. 255 Hz

81. The international pitch A is equivalent to ___ Hz.

  • A. 435
  • B. 440
  • C. 260
  • D. 255

82. The speed of the satellite increases as its height in orbit gets

  • A. lower
  • B. higher
  • C. closer to the moon
  • D. closer to the sun

83. What is the effective radiated power of a repeater with 50 watts transmitter power output \, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 6 dB antenna gain?

  • A. 158 W
  • B. 39.7 W
  • C. 251 W
  • D. 69.9 W

84. A cellular standard known as the cdmaOne.

  • A. IS-95
  • B. IS-136
  • C. IS-54
  • D. IS-100

85. What is the effective radiated power of a repeater with 50 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 7 dB antenna gain?

  • A. 300 W
  • B. 315 W
  • C. 31.5 W
  • D. 69.9 W

86. Which Ethernet system is restricted only to 100 m?

  • A. 10 Base T
  • B. 20 Base 2
  • C. 10 Base 5
  • D. 10 Base 1

87. What is the effective radiated power of a repeater with 75 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 10 dB antenna gain?

  • A. 600 W
  • B. 75 W
  • C. 18.75 W
  • D. 150 W

88. Which of the following regulates the ownership and operation of radio and television stations in the country?

  • A. PD 576-A
  • B. PD 756
  • C. PD 657
  • D. PD 677

89. What is the effective radiated power of a repeater with 75 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 6 dB antenna gain?

  • A. 37.6 W
  • B. 237 W
  • C. 150 W
  • D. 23.7 W

90. In GSM cellular system, the speech coding rate is ____.

  • A. 13 kbps
  • B. 8 kbps
  • C. 15 kbps
  • D. 20 kbps

91. What is the effective radiated power of a repeater with 100 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 10 dB antenna gain?

  • A. 800 W
  • B. 126 W
  • C. 12.5 W
  • D. 1260 W

92. Which NTC memorandum circular governs the rules and regulations about the manufacture, acquisition, sale and service of radio communication equipment?

  • A. MC No. 2-05-88
  • B. MC No. 2-04-88
  • C. MC No. 2-07-88
  • D. MC No. 2-09-88

93. What is the effective radiated power of a repeater with 120 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 6 dB antenna gain?

  • A. 601 W
  • B. 240 W
  • C. 60 W
  • D. 379 W

94. What do you call a short bit sequence sent typically 128 bits in digital signatures?

  • A. Hash
  • B. Public key
  • C. Private key
  • D. Password

95. What medium is used by IBM token ring network that operates at either 4 Mbps or 16 Mbps?

  • A. Twisted pair
  • B. Coaxial cable
  • C. Fiber-optic
  • D. Parallel-wire line

96. What is known as the final stage in the evolution of the GSM standard?

  • A. WAP
  • B. GPRS
  • C. EDGE
  • D. Bluetooth

97. According to KBP revised radio code which airtime below is classified class D for AM stations?

  • A. 6:00 AM to 12:00 NN
  • B. 12:00 NN to 6:00 PM
  • C. 9:00 PM to 12 Midnight
  • D. 12:00 Midnight to 5:00 AM

98. Encryption of data is important to ensure its privacy. It is most commonly achieved by using a ____.

  • A. public-key encryption
  • B. private-key encryption
  • C. password-key encryption
  • D. character set encryption

99. The speech coding rate in D-AMPS is ____.

  • A. 8 kbps
  • B. 13 kbps
  • C. 15 kbps
  • D. 20 kbps

100. Which of the following principal musical intervals is considered dissonant?

  • A. 7:8
  • B. 1:2
  • C. 5:8
  • D. 3:5

Complete List of Communications Engineering Exams: ECE Pre-Board

Check your work.


Published by: Froyd Wess15:20

Thursday, December 11, 2014

Communications Engineering Exam 8: ECE Pre-Board - Answers

Communications Engineering Exam 8 - Answers

Below are the answers key for the 100 items set of Practice Examination 8 in Communications Engineering composed of previous Board Exams Questions and cautiously selected questions from various topics in Communications Engineering (Electronics Systems and Technology) that could possibly be given in the board.

1. 0.99

2. Huygen’s principle

3. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency.

4. Phase differences between radio wave components of the same transmission, as experienced at the receiving station.

5. Radio waves may be bent.

6. Tropospheric ducting

7. The ratio between the deviation of a frequency modulated signal and the modulating frequency.

8. knife-edge diffraction

9. 60 cm

10. Radiation resistance plus ohmic resistance

11. A wave consisting of an electric field and a magnetic field at right angles to each other

12. 300 – 3000 MHz

13. 90 degrees

14. 40 km

15. The electric field is parallel to the earth.

16. The electric field rotates

17. 72 km

18. 36 meters high

19. Microwave

20. Salt water

21. 300 ohms

22. Frequency hopping

23. 0.66

24. 6 watts

25. Dielectrics in the line

26. Direct sequence

27. 30 to 300 kHz

28. 3 MHz to 30 MHz

29. 700 MHz

30. D

31. lowest, highest

32. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.

33. Velocity factor

34. RF energy moves slower along the coaxial cable

35. 3.51 meters

36. Optimum useable frequency (OUF).

37. 1.66

38. 300 MHz to 3 GHz

39. 4250 MHz to 4350 MHz

40. A frequency modulated continuous wave

41. Is the same direction as the electrostatic field of the antenna.

42. 1 watt

43. When comparing the gains of directional antennas

44. vertical, horizontal

45. Gain increases 6 dB

46. 118.000 MHz to 136.975 MHz (worldwide up to 151.975 MHz)

47. A fading effect caused by phase differences between radio wave components of the same transmission, as experienced at the receiving station

48.1.5

49. 2ξd

50. Space wave

51. 100 Hz

52. Both VLF and LF

53. Virtual height

54. 300 km

55. Flexible coaxial line

56. ½ to 2/3

57. 100 x 103 m/s

58. 0.25

59. 2.76 x 10-9 S/m

60. 150 Ω

61. 1.67

62. 2.8

63. The beamwidth decreases as the gain is increased.

64. 660 kHz

65. 2500 Ω

66. 352 m3

67. 0.8 – 1.2 sec.

68. 99.7 MHz

69. 999.8 kHz, 1000 kHz, and 1000.2 kHz

70. IF amplifier

71. Space noise

72. 500 Hz

73. Between 15 to 60

74. 0.54

75. 10,800

76. 2.089

77. The standing wave ratio is one.

78. The power traveling from the transmitter to the antenna.

79. The American National Standards Institute (ANSI).

80. internal receiver noise.

81. final RF stage

82. Midday

83. ± 12 KHz

84. Goniometer

85. GMDSS

86. Helical

87. an impedance mismatch between the load and the line.

88. Calorimeter

89. . Dominant mode

90. Doppler effect

91. 1.35 cm and 1.7 mm

92. 5 mm and 2.5 mm

93. 4130 km

94. F2 layer

95. distance-to-reuse ratio (D/R)

96. Frequency agility

97. Hexagon

98. 6

99. 10-12 W/m2

100. 5150 m/s

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Complete List of Communications Engineering Exams: ECE Pre-Board


Published by: Froyd Wess17:58

Communications Engineering Exam 8: ECE Pre-Board

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Communications Engineering Exam 8

This is 100 items set of Practice Examination 8 in Communications Engineering (Electronics Systems and Technology) composed of previous Board Exams Questions. Read each questions and choices 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 questions to increase the chance of passing the ECE Board Examination.

Start the Test Yourself Exam 8

1. What is the refractive index of an ionospheric layer with 100 x 105 free electrons per m3?

Assume frequency to be at 20 MHz.

  • A. 0.99
  • B. 0.15
  • C. 0.78
  • D. 0.85

2. “Each point on a spherical wavefront may be considered a source of secondary spherical wavefronts”. This is known as the

  • A. Snell’s law
  • B. D’Alembert’s principle
  • C. Appleton’s theory
  • D. Huygen’s principle

3. What is meant by the term deviation ratio?

  • A. The ratio of the audio modulating frequency to the center carrier frequency.
  • B. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency.
  • C. The ratio of the carrier center frequency to the audio modulating frequency.
  • D. The ratio of the highest audio modulating frequency to the average audio modulating frequency.

4. What is the major cause of selective fading?

  • A. Small changes in the beam heading at the receiving station.
  • B. Large changes in the height of the ionosphere, as experience at the receiving station.
  • C. Time differences between the receiving and transmitting stations.
  • D. Phase differences between radio wave components of the same transmission, as experienced at the receiving station.

5. What phenomenon causes the radio-path horizon distance to exceed the geometric horizon?

  • A. E-layer skip.
  • B. D-layer skip.
  • C. Auroral skip.
  • D. Radio waves may be bent.

6. What propagation condition is usually indicated when a VHF signal is received from a station over 500 miles away?

  • A. D-layer absorption
  • B. Faraday rotation
  • C. Tropospheric ducting
  • D. Moonbounce

7. What is meant by the term modulation index?

  • A. The processor index.
  • B. The ratio between the deviation of a frequency modulated signal and the modulating frequency.
  • C. The FM signal-to-noise ratio.
  • D. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency.

8. 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

  • A. eddy-current phase effect
  • B. knife-edge diffraction
  • C. shadowing
  • D. mirror refraction effect

9. What is the wavelength of a signal at 500 MHz?

  • A. 0.062 cm
  • B. 6 meters
  • C. 60 cm
  • D. 60 meters

10. What is included in the total resistance of an antenna system?

  • A. Radiation resistance plus space impedance
  • B. Radiation resistance plus transmission resistance
  • C. Transmission line resistance plus radiation resistance
  • D. Radiation resistance plus ohmic resistance

11. What are electromagnetic waves?

  • A. Alternating currents in the core of an electromagnet
  • B. A wave consisting of two electric fields at right angles to each other
  • C. A wave consisting of an electric field and a magnetic field at right angles to each other
  • D. A wave consisting of two magnetic fields at right angles to each other

12. The band of frequencies least susceptible to atmospheric noise and interference is:

  • A. 30 – 300 kHz
  • B. 300 – 3000 kHz
  • C. 3 – 30 MHz
  • D. 300 – 3000 MHz

13. What is the relationship in degrees of the electrostatic and electromagnetic fields of an antenna?

  • A. 0 degree
  • B. 45 degrees
  • C. 90 degrees
  • D. 180 degrees

14. For a space wave transmission, the radio horizon distance of a transmitting antenna with a height of 100 meters is approximately:

  • A. 10 km
  • B. 40 km
  • C. 100 km
  • D. 400 km

15. What is meant by referring to electromagnetic waves as horizontally polarized?

  • A. The electric field is parallel to the earth.
  • B. The magnetic field is parallel to the earth.
  • C. Both the electric and magnetic fields are horizontal
  • D. Both the electric and magnetic fields are vertical

16. What is meant by referring to electromagnetic waves as having circular polarization?

  • A. The electric field is bent into a circular shape.
  • B. The electric field rotates
  • C. The electromagnetic wave continues to circle the earth
  • D. The electromagnetic wave has been generated by a quad antenna

17. If a transmitting antenna is 100 meters high and a separate receiving antenna is 64 meters high, what is the maximum space wave communication distance possible between them?

  • A. 18 km
  • B. 72 km
  • C. 164 km
  • D. 656 km

18. A receiver is located 64 km from a space wave transmitting antenna that is 100 meters high. Find the required height of the receiving antenna.

  • A. 36 meters high
  • B. 64 meters high
  • C. 100 meters high
  • D. 182.25 meters high

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

  • A. Ground wave
  • B. Microwave
  • C. Sky wave
  • D. Space wave

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

  • A. Salt water
  • B. Fresh water
  • C. Sandy
  • D. Rocky

21. What is the input terminal impedance at the center if a folded dipole antenna?

  • A. 300 ohms
  • B. 72 ohms
  • C. 50 ohms
  • D. 450 ohms

22. What is the term used to describe a spread spectrum communications system where the center frequency if a conventional carrier is altered many time per second in accordance with a pseudo-random list of channels?

  • A. Frequency hopping
  • B. Direct sequence
  • C. Time-domain frequency modulation
  • D. Frequency compandored spread spectrum

23. What is the velocity factor for non-foam dielectric 50 or 75 ohm flexible coaxial cable such as RG 8, 11, 58 and 59?

  • A. 2.70
  • B. 0.66
  • C. 0.30
  • D. 0.10

24. If a transmission line has a power loss of 6 dB per 100 feet, what is the power at the feed point to the antenna at the end of a 200 foot transmission line fed by a 100 watt transmitter?

  • A. 70 watts
  • B. 50 watts
  • C. 25 watts
  • D. 6 watts

25. What determines the velocity factor in a transmission line?

  • A. The termination impedance
  • B. The line length
  • C. Dielectrics in the line
  • D. The center conductor resistivity

26. What term is used to describe a spread spectrum communications system in which a very fast binary bit stream is used to shift the phase of an RF carrier?

  • A. Frequency hopping
  • B. Direct sequence
  • C. Binary phase-shift keying
  • D. Phase compandored spread spectrum

27. Which of the following frequency bands is best suited for ground wave propagation?

  • A. 30 to 300 kHz
  • B. 300 kHz to 3 MHz
  • C. 3 MHz to 30 MHz
  • D. 30 MHz to 300 MHz

28. Which of the following frequency bands is best suited for sky wave propagation?

  • A. 30 to 300 kHz
  • B. 3 MHz to 30 MHz
  • C. 30 MHz to 300 MHz
  • D. 3 GHz to 30 GHz

29. What is the seventh harmonic of a 100 MHz quarter wavelength antenna?

  • A. 14.28 MHz
  • B. 107 MHz
  • C. 149 MHz
  • D. 700 MHz

30. Which if the following layers of the ionosphere has no effect on sky wave propagation during the hours of darkness?

  • A. D
  • B. E
  • C. F1
  • D. F2

31. Skip distance can be maximized by using the ____ radiation angle possible and the ____ frequency that will be refracted at that angle.

  • A. lowest, lowest
  • B. lowest, highest
  • C. highest, lowest
  • D. highest, highest

32. What is the meaning of the term “velocity factor” of a transmission line?

  • A. The ratio of the characteristic impedance of the line to the terminating impedance
  • B. The index of shielding for coaxial cable.
  • C. The velocity of the wave on the transmission line multiplied by the velocity of light in a vacuum.
  • D. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.

33. What is the term for the ratio of actual velocity at which a signal travels through a line to the speed of light in a vacuum?

  • A. Velocity factor
  • B. Characteristic impedance
  • C. Surge impedance
  • D. Standing wave ratio

34. Why is the physical length of a coaxial cable transmission line shorter than its electrical length?

  • A. Skin effect is less pronounced in the coaxial cable
  • B. RF energy moves slower along the coaxial cable
  • C. The surge impedance is higher in the parallel feed line
  • D. The characteristic impedance is higher in the parallel feed line

35. What would be the physical length of a typical coaxial transmission line that is electrically one-quarter wavelength long at 14.1 MHz?

  • A. 20 meters
  • B. 3.51 meters
  • C. 2.33 meters
  • D. 0.25 meter

36. To obtain the most reliable sky wave propagation the ____ should be used.

  • A. Lowest useable frequency (LUF).
  • B. Maximum useable frequency (MUF).
  • C. Optimum useable frequency (OUF).
  • D. Critical frequency

37. What is the deviation ratio for an FM-phone signal having a maximum frequency swing of plus or minus 5 kHz and accepting a maximum modulation rate of 3kHz?

  • A. 60
  • B. 0.16
  • C. 0.6
  • D. 1.66

38. Tropospheric scatter is a method of sky wave propagation for which of the following frequency bands?

  • A. 300 kHz to 3 MHz
  • B. 3 MHz to 30 MHz
  • C. 30 MHz to 300 MHz
  • D. 300 MHz to 3 GHz

39. What is the frequency range of an aircraft’s radio altimeter?

  • A. 962 MHz to 1213 MHz
  • B. 329.15 MHz to 335.00 MHz
  • C. 4250 MHz to 4350 MHz
  • D. 108.00 MHz to 117.95 MHz

40. What type of transmission is radiated from an aircraft’s radio altimeter antenna?

  • A. An amplitude modulated continuous wave
  • B. A pulse position modulated UHF signal
  • C. A differential phase shift keyed UHF signal
  • D. A frequency modulated continuous wave

41. The polarization of a radio wave:

  • A. Is perpendicular to the electrostatic field of the antenna
  • B. Is the same direction as the electrostatic field of the antenna.
  • C. Is the same direction as the magnetic field of the antenna.
  • D. Is perpendicular to both the electrostatic and magnetic fields of the antenna.

42. A coaxial cable has 7dB of reflected power when the input is 5 watts. What is the output of the transmission line?

  • A. 5 watts
  • B. 2.5 watts
  • C. 1.25 watts
  • D. 1 watt

43. When is it useful to refer to an isotropic radiator?

  • A. When comparing the gains of directional antennas
  • B. When testing a transmission line for standing wave ratio
  • C. When (in the northern hemisphere) directing the transmission in a southerly direction
  • D. When using a dummy load to tune a transmitter

44. Most AM broadcasts employ ___ polarization while most FM broadcasts employ ___ polarization of the radio wave.

  • A. vertical, vertical
  • B. vertical, horizontal
  • C. horizontal, vertical
  • D. horizontal, horizontal

45. How does the gain of a parabolic dish type antenna change when the operating frequency is doubled?

  • A. Gain does not change
  • B. Gain is multiplied by 0.707
  • C. Gain increases 6 dB
  • D. Gain increases 3 dB

46. What is the frequency range of an aircraft’s Very High Frequency (VHF) communications?

  • A. 118.000 MHz to 136.975 MHz (worldwide up to 151.975 MHz)
  • B. 108.000 MHz to 117.95 MHz
  • C. 329.15 MHz to 335.00 MHz
  • D. 2.0000 MHz to 29.999 MHz

47. What is a selective fading effect?

  • A. A fading effect caused by small changes in beam heading at the receiving station.
  • B. A fading effect caused by phase differences between radio wave components of the same transmission, as experienced at the receiving station.
  • C. A fading effect caused by large changes in the height of the ionosphere, as experienced at the receiving station
  • D. A fading effect caused by time differences between the receiving and transmitting stations.

48. If the velocity of propagation in a certain medium is 200x106 m/s, what is its refractive index?

  • A. 1.3
  • B. 1.5
  • C. 1.27
  • D. 0.67

49. What is the resultant field strength at the receiving antenna in space wave propagation under case 2?

  • A. 0
  • B. ξd
  • C. 2ξd
  • D. 3ξd

50. The decimetric wave is using what method of propagation?

  • A. Ground wave
  • B. Space wave
  • C. Sky wave
  • D. Tropospheric wave

51. What is the typical frequency used for communicating to submerged submarines?

  • A. 100 Hz
  • B. 500 Hz
  • C. 4 kHz
  • D. 200 Hz

52. Which frequency bands can be refracted during the day by the D layer?

  • A. VLF
  • B. MF
  • C. LF
  • D. Both VLF and LF

53. What height of an ionized layer is determined from the time interval between the transmitted signal and the ionospheric echo at vertical incidence?

  • A. Virtual height
  • B. Apparent height
  • C. Actual height
  • D. Effective height

54. During the night when the F2 layer combines with F1 layer it falls to what approximate height?

  • A. 250 km
  • B. 350 km
  • C. 300 km
  • D. 400 km

55. Which of the following is considered the most frequently used transmission line?

  • A. Two-wire open line
  • B. Twin lead
  • C. Rigid coaxial line
  • D. Flexible coaxial line

56. The antenna effective height is ____ to ____ of the actual height.

  • A. ½ to 2/3
  • B. ½ to ¾
  • C. ¼ to 2/3
  • D. ¼ to ¾

57. What is the propagation velocity of a signal in a transmission line whose inductance and capacitance are 5μH/m and 20μF/m respectively?

  • A. 100 x 103 m/s
  • B. 100 m/s
  • C. 10 x 103 m/s
  • D. 100 x 106 m/s

58. What is the phase coefficient in radians per unit length of a transmission line at the frequency of 10 MHz if the velocity of propagation is 2.5 x 108 m/s?

  • A. 0.25
  • B. 2.5
  • C. 0.35
  • D. 3.5

59. Determine the conductance of a two-wire open line with the following parameters: D = 4 in., d = 0.1 in. and ρ = 2.6x108 Ω-m.

  • A. 2.76 x 10-9 S/m
  • B. 2.76 x 10-6 S/m
  • C. 2.76 x 10-12 S/m
  • D. 2.76 x 10-3 S/m

60. What is the input impedance of a transmission line if its characteristic impedance is 300 Ω and the load is 600 Ω? Assume a quarter wavelength section only.

  • A. 150 kΩ
  • B. 150 mΩ
  • C. 150 Ω
  • D. 2 Ω

61. Determine the standing wave ratio of a 300-Ω line whose load is 400+j150 Ω.

  • A. 3.55
  • B. 1.67
  • C. 5.53
  • D. 3.35

62. What is the optimum volume per person of rooms for speech?

  • A. 2.8
  • B. 3.1
  • C. 4.2
  • D. 5.1

63. What happens to the beamwidth of an antenna as the gain is increased?

  • A. The beamwidth increases geometrically as the gain is increased.
  • B. The beamwidth increases arithmetically as the gain is increased.
  • C. The beamwidth is essentially unaffected by the gain of the antenna.
  • D. The beamwidth decreases as the gain is increased.

64. A superhet receiver has an IF of 455 kHz and is experiencing image-channel interference on a frequency of 1570 kHz. The receiver is tuned to

  • A. 1115 kHz
  • B. 660 kHz
  • C. 2025 kHz
  • D. 910 kHz

65. What is the end impedance of a half-wave dipole?

  • A. 73 Ω
  • B. 72 Ω
  • C. 250 Ω
  • D. 2500 Ω

66. What volume of the chamber is required to measure absorption coefficient at 100 Hz?

  • A. 125 m3
  • B. 50 m3
  • C. 150 m3
  • D. 352 m3

67. What is the optimum reverberation time at 500 Hz for a cinema?

  • A. 0.8 – 1.2 sec.
  • B. 0.9 – 1.3 sec.
  • C. 0.6 – 0.8 sec.
  • D. 0.45 – 0.55 sec.

68. An FM receiver whose intermediate frequency is 10.7 MHz, is experiencing image channel interference from a station transmitting on 121.1 MHz. If the local oscillator is tracking above, the receiver is tuned to

  • A. 131.8 MHz
  • B. 110.4 MHz
  • C. 142.5 MHz
  • D. 99.7 MHz

69. A 1 Mhz carrier is amplitude modulated by a pure 200-Hz audio test tone. Which of the following combinations of frequencies represent the total content of the AM signal?

  • A. 1 MHz and 200 Hz
  • B. 1 MHz and 1000.2 kHz
  • C. 999.8 kHz, 1000 kHz, and 1000.2 kHz
  • D. 999.8 kHz and 1000.2 kHz

70. What establishes the receiver bandwidth?

  • A. RF amplifier
  • B. Mixer
  • C. Local oscillator
  • D. IF amplifier

71. What noise type is observable between 8 MHz to somewhat above 1.43 GHz or up to 1.5 GHz?

  • A. Solar noise
  • B. Space noise
  • C. Galactic noise
  • D. Cosmic noise

72. Flicker noise is a poorly understood form of noise which may be completely ignored about above ____.

  • A.100 Hz
  • B. 200 Hz
  • C. 400 Hz
  • D. 500 Hz

73. What is the typical gain of a rhombic antenna?

  • A. Between 15 to 60
  • B. Between 20 to 90
  • C. Between 50 to 75
  • D. Between 10 to 25

74. What illumination factor is normally considered in computing parabolic antenna gain in microwave communications?

  • A. 0.54
  • B. 0.65
  • C. 0.75
  • D. 0.85

75. How many voice band channels are there in a superjumbo group?

  • A. 600
  • B. 900
  • C. 10,800
  • D. 3,600

76. In acoustics, what is the reference pressure in lb/ft2 unit?

  • A. 2x10-5
  • B. 0.0002
  • C. 2.089
  • D. 2.980

77. Which of the following characterizes a properly terminated transmission line?

  • A. The line loss is minimum.
  • B. The standing wave ratio is minimum.
  • C. The input impedance is twice the load impedance.
  • D. The standing wave ratio is one.

78. What is the meaning of forward power?

  • A. The power traveling from the transmitter to the antenna.
  • B. The power radiated from the top of an antenna system.
  • C. The power produced during the positive half of an RF cycle.
  • D. The power used to drive a linear amplifier.

79. What organization has published safety guidelines for the maximum limits of RF energy near the human body?

  • A. The American National Standards Institute (ANSI).
  • B. The Environmental Protection Agency (EPA).
  • C. The Federal Communications Commission (FCC).
  • D. The Institute Of Electrical and Electronics Engineers (IEEE).

80. When no signal is being received, the loudspeaker is not entirely silent as a result of the presence of

  • A. parasitic oscillations in some of the receiver stages.
  • B. negative feedback in each stage.
  • C. spurious frequencies as a result of improper neutralization.
  • D. internal receiver noise.

81. When measuring a transmitter’s frequency against a suitable standard, the frequency to be measured is taken from the

  • A. oscillator stage
  • B. intermediate amplifier
  • C. buffer stage
  • D. final RF stage

82. When the is the ionosphere most ionized?

  • A. Dusk
  • B. Midnight
  • C. Dawn
  • D. Midday

83. Cellular radios use FM with a maximum deviation of

  • A. ± 30 KHz
  • B. ± 75 KHz
  • C. ± 25 KHz
  • D. ± 12 KHz

84. What device measures the angle between two radio frequencies and also the direction of propagation of a wave?

  • A. Densimeter
  • B. Absorption wavemeter
  • C. Goniometer
  • D. Ergometer

85. An automated ship-to-shore distress alerting system using satellites and advanced terrestrial communications systems.

  • A. GPS
  • B. Iridium system
  • C. INMARSAT
  • D. GMDSS

86. What antenna can be used to minimize the effect of Faraday rotation of polarization?

  • A. Dipole
  • B. Parabolic
  • C. Helical
  • D. Rhombic

87. The presence of standing waves on a transmission line is the result of

  • A. a high level of attenuation on the line.
  • B. terminating the line by a resistive load equal in value to the surge impedance
  • C. reducing the input power to below its critical level.
  • D. an impedance mismatch between the load and the line.

88. What device measures rf power by measuring the heat the rf power generates?

  • A. Calorimeter
  • B. Goniometer
  • C. Spectrum meter
  • D. Oscilloscope

89. What is considered the most efficient mode in terms of energy transfer in waveguides?

  • A. Dominant mode
  • B. Normal mode
  • C. Conventional mode
  • D. Vertical mode

90. In acoustics, _____ is the apparent change in frequency or pitch when a sound source moves either toward or away from a listener.

  • A. flanking
  • B. reverberation
  • C. Doppler effect
  • D. echo

91. Which of the following wavelengths where absorption of electromagnetic waves becomes peak due to vibrational resonances in the water vapor molecule?

  • A. 1.35 cm and 1.7 mm
  • B. 1.5 mm and 5mm
  • C. 1.35 dm and 1.7cm
  • D. 1.5 cm and 5 mm

92. Oxygen molecule absorption peaks to electromagnetic wave are at what wavelengths?

  • A. 1.35 mm and 1.7 μm
  • B. 1.35 cm and 1.7 mm
  • C. 5 cm and 2.5 cm
  • D. 5 mm and 2.5 mm

93. The approximate single-hop nighttime range of F2 layer is ____.

  • A. 3000 km
  • B. 3840 km
  • C. 4130 km
  • D. 2350 km

94. What ionospheric layer has a daytime approximate critical frequency of 8 MHz?

  • A. F2 layer
  • B. F1 layer
  • C. E layer
  • D. D layer

95. In cellular system, _____ defines the geographic distance that is required between cells using identical frequencies in order to avoid interference between the radio transmissions at these cells.

  • A. frequency-reuse ratio
  • B. distance-to-reuse ratio (D/R)
  • C. reuse format plan ratio
  • D. reuse factor

96. What do you call the ability of a mobile phone to change from one channel (frequency) to another?

  • A. Frequency agility
  • B. Frequency handoff
  • C. Frequency handover
  • D. Frequency switch

97. What mathematical plane figure is ideal in cellular system design and engineering it graphically and functionally depicts overlapping radio coverage between and among adjacent cell base stations?

  • A. Hexagon
  • B. Octagon
  • C. Pentagon
  • D. Nonagon

98. In cellular system, the average lead time to install a new base station is approximately ____ months to a year.

  • A. 4
  • B. 5
  • C. 6
  • D. 10

99. What is considered the threshold of audibility at 3000 Hz?

  • A. 10-12 W/m2
  • B. 10-16 W/m2
  • C. 10-12 W/cm2
  • D. 10-15 W/cm2

100. At one atmospheric pressure, what is the approximate speed of sound in steel?

  • A. 5150 m/s
  • B. 5150 ft/s
  • C. 4990 m/s
  • D. 4990 ft/s

Complete List of Communications Engineering Exams: ECE Pre-Board

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Published by: Froyd Wess17:56