Communications Engineering Mastery Test 15: ECE Pre-Board

(Last Updated On: January 13, 2022) This is 100 items Practice Examinations set 15 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 15

Choose the letter of the best answer in each questions.

1. Technique employed by wireless infrastructure systems that lowers the power of a signal in a cell site whenever the site detects that the user’s phone is close to the source of the signal

• B. Pre-emphasis
• C. Level down
• D. Power attenuation

Solution:

2. A relative range of frequencies that can carry a signal without distortion on a transmission medium

• A. Doppler frequency
• B. Carrier
• C. Bandwidth or pipe
• D. Channel

Solution:

3. Suppose a TV signal has 10.5 microseconds of horizontal blanking per line and 21 lines of vertical blanking per field. What is the percentage of total time that is occupied by blanking?

• A. 22.92%
• B. 93.22%
• C. 11.45%
• D. 16.67%

Solution:

4. Estimate the bandwidth occupied by the sound portion of a TV transmission in US.

• A. 25 kHz
• B. 800 kHz
• C. 80 kHz
• D. 200 kHz

Solution:

5. What is the purpose of using alternate mark inversion and return to zero encoding of data?

• A. faster digital data transmission
• B. assist in clock recovery
• C. more efficient transmission of analog data
• D. reduced susceptibility to noise

Solution:

6. A measure of the number of subscribers who leave or switch to another carrier’s service

• A. Offered traffic
• B. Churn
• C. Carried traffic
• D. Population

Solution:

7. The power amplifier of an AM transmitter has an output power of 50 W and an efficiency of 60% and is collector modulated. How much audio power is required to be supplied to this stage for 100% modulation?

• A. 833 W
• B. 41.66 W
• C. 30 W
• D. 15 W

Solution:

8. The old standard unit for measuring the activity of a given radioactive sample which is equivalent to the activity of 1 gram of radium.

• A. Curie
• B. Becquerel
• D. Rem

Solution:

9. A combination of two or more integrated circuits on one module

• A. PCB
• B. Combo chip
• C. TTL
• D. Chip set

Solution:

10. The term applied to a phone that will work on 800 MHz analog, 800 MHz digital and 1900 MHz (also known as 1.9 GHz) frequencies

• A. Tri-mode
• B. Tri Band
• C. Dual Band
• D. Dual-mode

Solution:

11. A pen-based tablet computer used on a wireless local area network

• A. node
• B. source
• C. thin client
• D. master

Solution:

12. 1 Petabits is equivalent to how many bits of digital information?

• A. 1 x 1015 bits
• B. 1, 073, 741, 824 bits
• C. 1, 099, 511, 627, 776 bits
• D. 1, 125, 899, 906, 842, 624 bits

Solution:

13. Where is de-emphasis added in a stereo FM system?

• A. before the matrix at the TX
• B. before the matrix at the R
• C. after the matrix at the TX
• D. after the matrix at the RX

Solution:

14. How many electron beams actually leave the electron gun of a single-gun color CRT?

• A. 1
• B. 2
• C. 3
• D. 4

Solution:

15. Determine the quality factor necessary for a single sideband filter with a 1-MHz carrier frequency, 80 dB unwanted suppression and 200-Hz frequency separation.

• A. 15,000
• B. 125,000
• C. 12,000
• D. 25,000

Solution:

16. A rectangular waveguide has a width of 0.6 inch. Calculate the waveguide cut-off frequency.

• A. 12.84 GHz
• B. 5.84 GHz
• C. 10.84 GHz
• D. 9.84 GHz

Solution:

17. A permanent-magnet ring on the neck of the tube is used for ________.

• A. scanning
• B. centering
• C. deflecting
• D. focusing

Solution:

18. The IS-95 CDMA standard developed by Qualcomm Inc

• A. WCDMA
• B. IMT-DS
• C. cdmaOne
• D. IMT-SC

Solution:

19. The process of creating more coverage and capacity in a geographic area by having more than one cell cover the same area that a single cell originally did

• A. Cell splitting
• B. Frequency reuse
• C. Cell reuse
• D. Cell site

Solution:

20. Gregorian antenna is consist of

• A. Main paraboloid reflector and an ellipsoid subreflector
• B. Main paraboloid reflector and a hyperboloid subreflector
• C. Main ellipsoid reflector and a hyperboloid subreflector
• D. Main hyperboloid reflector and an ellipsoid subreflector

Solution:

21. A logic channel carrying network information rather than the actual voice or data messages transmitted over the network

• A. Control channel
• B. Backup channel
• D. Message channel

Solution:

22. In which ITU region is Philippines?

• A. ITU Region 1
• B. ITU Region 2
• C. ITU Region 3
• D. ITU Region 4

Solution:

23. What is the result of over deviation in an FM transmitter?

• A. Increased transmitter range
• B. Increased transmitter power
• C. Poor carrier suppression
• D. Out-of-channel emissions

Solution:

24. What is the output PEP from a transmitter if an oscilloscope measures 500 volts peak-to-peak across a 50-ohm resistor connected to the transmitter output?

• A. 500 watts
• B. 625 watts
• C. 1250 watts
• D. 2500 watts

Solution:

25. _________ is the process of impressing or imparting a low frequency source information (voice, audio, video, or data) onto a high-frequency bandpass signal with a carrier frequency fc by the introduction of amplitude, frequency or phase perturbation.

• A. Mixing
• B. Modulation
• C. Heterodyning
• D. Multiplexing

Solution:

26. A trade group representing cellular, PCS and enhanced specialized mobile radio carriers

• A. CTIA (Cellular Telecommunications Industry Association)
• B. EIA (Electronic Industry Association)
• C. ANSI
• D. SONET

Solution:

27. Which of the following can cause frequency intermodulation products in a system?

• A. Antenna
• B. Only semiconductor junctions like diodes and transistors (amplifiers)
• C. Cable connectors, bolted or riveted antenna panels, isolators and circulators
• D. Both B and C

Solution:

28. What type of filter is used in the IF section of receivers to block energy outside a certain frequency range?

• A. An input filter
• B. A low-pass filter
• C. A band-pass filter
• D. A high-pass filter

Solution:

29. A secret number issued to a cellular phone that is used in conjunction with a subscriber’s shared secret data information for authentication

• A. MIN (Mobile Identification Number)
• B. A-key
• C. IMSI (International Mobile Subscriber Identity)
• D. Cipher key

Solution:

30. A feature on wireless phones where you enter just one or two digits from the keypad and then initiate the call. The phone searches its speed dial directory and associates the entire number with the two-digit speed dial position you’ve entered.

• A. DTMF dialing
• B. Voice dialing
• C. Pulse dialing
• D. Abbreviated dialing

Solution:

31. Which of these pairs of materials in the triboelectric series have the greatest charge transfer potential?

• A. Rubber Balloon & Celluloid
• B. Silk & Wool
• C. Metal & Nonmetal
• D. Glass & Hard Rubber

Solution:

32. A method of taking signal strength measurements in a cellular coverage area

• B. drive test
• C. boresighting
• D. field strength

Solution:

33. To facilitate frequency planning, ITU divide the world intro three regions. Region 2 includes __________.

• A. North and South America and Greenland
• B. Europe, Africa and Mongolia
• C. Asia Pacific, Australia, and the southwest Pacific
• D. Philippines, and Southeast Asia

Solution:

34. In satellite communication, what does sun- synchronous means?

• A. They cross the equator at the same local time each month
• B. They cross the equator at the same local time 2x each day
• C. They cross the equator at the same local time each day
• D. They cross the equator at the same local time every 27 days

Solution:

35. During a network analyzer calibration, why are both a short circuit and an open circuit used?

• A. To determine the power output
• B. To determine the characteristic impedance of the measurement system
• C. Both are easy to produce to at high accuracy
• D. They average to 50 ohms in an RF system

Solution:

36. At what frequency is electromagnetic energy maximally absorbed due to oxygen in the atmosphere?

• A. 180 GHz
• B. 63 GHz
• C. 22 GHz
• D. 110 GHz

Solution:

37. The location where the wireless antenna and network communications equipment is placed

• A. Network
• B. Cell site
• C. POP (Point of Presence)
• D. Footprint

Solution:

38. What does the term "ruggedness" refer to in wireless power amplifiers?

• A. Ability to withstand load mismatch
• B. Ability to withstand thermal stress
• C. Ability to withstand mechanical stress
• D. All the above

Solution:

39. In which semiconductor technology are the majority of cellphone PAs manufactured?

• A. GaAs/InGaP
• B. GaN
• C. SiGe
• D. Si/SiCMOS

Solution:

40. What is a major advantage of Low Temperature Co-fired Ceramic (LTCC) substrates?

• A. Better thermal dissipation
• B. Lower bill of materials
• C. Densely integrated passive components
• D. All the above

Solution:

41. What do you call the center of mass of a two-body system such as the earth and the moon?

• A. orthocentre
• B. barycenter
• C. ethnocenter
• D. geocenter

Solution:

42. The portion of the wireless system’s infrastructure that is responsible for sending and receiving the actual radio signals over the airwaves in a 3G environment

• A. Base station controller
• B. Node B
• C. Gateway
• D. Base transceiver station

Solution:

43. Spectrum-efficient technology that establishes a queue to handle demand for voice or data channels

• A. Traffic
• B. Multiplexing
• C. Demand Accessing
• D. Trunking

Solution:

44. A wireless phone programmed with stolen or duplicated electronic serial and mobile identification numbers

• A. RAID
• B. Backup
• C. Clone
• D. Party line

Solution:

45. A satellite is orbiting the equatorial plane with a period from perigee to perigee of 12 hours. Given the eccentricity is 0.002, calculate the semi-major axis. (Use Rearth = 6378.1414 km)

• A. 25,813 km
• B. 24,781 km
• C. 22,333 km
• D. 26,597 km

Solution:

46. Fourier analysis often allows complex signals to be express as a series of __________.

• A. sinusoids
• B. pulse
• C. ellipse
• D. rectified signals

Solution:

47. A geographic area within a wireless system that is covered by the signal sent and received by the transmitter and receiver equipment located within that area

• B. Footprint
• C. Hotspot
• D. Cell

Solution:

48. Satellite technology to transmit calls from one point on Earth to a satellite and back down to another point

• A. Activetech
• B. Bent pipe technology
• C. Iridium
• D. Global tracking

Solution:

49. Who is known as ”The Father of Radar?”

• A. Walter Eugene O’Reilly
• B. Albert Einstein
• C. Oliver Heaviside
• D. Robert Watson-Watt

Solution:

50. Which flying (movement) condition will always result in a Doppler speed of 0 m/s?

• A. Speeds at odd integer multiples of antenna rotation rate
• B. Perfect concentric circle around antenna at constant altitude
• C. Speeds at even integer multiples of antenna rotation rate
• D. Perfectly constant speed into/out of the antenna boresight

Solution:

51. The technology that enables data connections between electronic devices such as desktop computers, wireless phones, electronic organizers and printers in the 2.4 GHz range

• A. Bluetooth
• B. MMDS (Multipoint Multichannel Distribution system)
• C. LMDS (Local Multipoint Distribution System)
• D. IrDA (Infrared Data Association)

Solution:

52. Using a wide-bandwidth channel for voice, data and/or video services

• A. Bandwidth
• C. Narrowband
• D. Baseband

Solution:

53. For a parabolic antenna of 3m diameter transmitting a 6-GHz wave has a far field zone that begins at approximately

• A. 7.06 m
• B. 70.6 m
• C. 360 m
• D. 36 m

Solution:

54. What is the term used for maintaining a satellite in its correct orbital position?

• A. Attitude control
• B. Station keeping
• C. Attitude maneuvering
• D. Spin stabilization

Solution:

55. Computer systems to help dispatch personnel and vehicles, commonly used by public-safety agencies

• B. Public wireless amplifier

Solution:

56. A pager’s unique electronic identification number on the back of the device

• A. Back code
• B. Bar code
• C. Cap code
• D. Access Code

Solution:

57. Find the total number of pixels and the highest video bandwidth of NTSC system television

• A. 75 pixel, 4.27 MHz
• B. 775 pixel, 5.7 MHz
• C. 775 pixel, 4.27 MHz
• D. 575 pixel, 5.7 MHz

Solution:

58. Telephones, PBXs and other communications devices located in the home or office

• B. Terminal Equipment (TE)
• C. CPE (Customer Premise Equipment)
• D. MUX (Multiplxer)

Solution:

59. Slang term for someone who breaks an encrypted computer code or circuitry

• A. Programmer
• B. Cracker
• C. Engineer
• D. Hacker

Solution:

60. Interference in a wireless communications system that stems from other conversations in nearby cells using the same channel

• A. hits
• B. Intercommunication
• C. Crosstalk
• D. jitter

Solution:

61. What is the cause of trouble when there is no picture and no sound, with normal raster in a TV receiver?

• A. The trouble must be in the sound circuits, after the sound take-off points
• B. This trouble is in the signal circuits, before the sound take-off point, because both the picture and sounds are affected.
• C. The trouble must be in the vertical deflection oscillator and the vertical output stage
• D. This trouble means the raster and the signal circuits are not operating.

Solution:

62. Mathematical process that allows complex signals to be express as a series of sinusoids.

• A. Bessel Function
• B. Taylor Series
• C. Fourier analysis
• D. Heaviside Expansion

Solution:

63. Synthetic Aperture Radar (SAR) radar is mostly likely to be located on which platform?

• A. Airplane
• B. Ship
• C. Ambulance
• D. Police car

Solution:

64. Which of the following statements comparing a transverse wave and a longitudinal wave are correct?

(1) When a transverse wave travels through a medium, the particles in the medium do not move along with the wave. However, when a longitudinal wave travels through a medium, the particles in the medium move along with the wave.

(2) In a transverse wave, the vibrations of the transmitting medium are perpendicular to the direction of travel of the wave. In a longitudinal wave, the vibrations are along the direction of travel of the wave.

(3) The wave equation applies to both transverse waves and longitudinal waves.

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)

Solution:

65. A method of making a network system or a computer resistant to software errors, hardware problems or power failures

• A. Firewall
• B. Kerberos
• C. Fault-tolerant
• D. Sledge Hammer

Solution:

66. The frequency spectrum near 2 GHz used for land based microwave and some mobile satellite communications

• A. X-band
• B. Ku-band
• C. S-band
• D. C-band

Solution:

67. Satellite in high altitude orbit are typically park in a temporary orbit to between the initial low earth orbit and the final high-altitude orbit to minimize the energy required for transfer, and such orbit is known as

• A. Stephen transfer orbit
• B. Clarke transfer orbit
• C. Pierce transfer orbit
• D. Hohmann transfer orbit

Solution:

68. Two equal amplitude tones have a power of +10 dBm, and generate a pair of equal amplitude 3rd-order intermodulation products at -20 dBm. What is the 2-tone, 3rd-order intercept point (IP3) of the system?

• A. +25 dBm
• B. +20 dBm
• C. +40 dBm
• D. +15 dBm

Solution:

69. What is a primary advantage to using 90 degree (quadrature) hybrid couplers in amplifier designs?

• A. Low noise figure
• B. Input/output impedance not dependent on devices as long as device impedances are equal
• C. Wider bandwidth possible
• D. Higher S/N ratio

Solution:

70. In a composite video signal what is the relationship between the amplitude of the signal and the intensity of the electron beam in the receiver picture tube?

• A. No effect
• B. The lower the amplitude the darker the picture
• C. The greater the amplitude the lighter the picture
• D. The greater the amplitude the darker the picture

Solution:

71. What is the power dynamic range of an ideal 12-bit analog-to-digital converter (ADC)?

• A. 12.87 dB
• B. 36.12 dB
• C. 72.25 dB
• D. 120 dB

Solution:

72. An ideal 10 dB attenuator is added in front of a load that has a 2.00:1 VSWR. What is the resulting VSWR of the load + attenuator?

• A. 12.0:1
• B. 2.10:1
• C. 1.07:1
• D. 5.4:1

Solution:

73. What is the thermal noise power in a 1 MHz bandwidth when the system temperature is 15 degrees Celsius (assume gain and noise figure are 0 dB)?

• A. -114.0 dB
• B. -114.0 dBm/Hz
• C. -114.0 dBm
• D. -114.0 dBw

Solution:

74. Find the energy in one photon at a wavelength of 1310 nm.

• A. 0.94 eV
• B. 1.52 eV
• C. 1.89 ev
• D. 5.13 eV

Solution:

75. An uplink at 14 GHz requires a saturation flux density of -91.4 dBW/m2 and an input backoff of 11 dB. The satellite Gt is -6.7dBK-1, and receiver feeder losses amount to 0.6 dB. Calculate the C/N density ratio.

• A. 37.93 dB
• B. 55.69 dB
• C. 74.5 dB
• D. 83.66 dB

Solution:

76. What is the carrier level for blanking?

• A. 67.5%
• B. 12.5% + 2.5%
• C. 100%
• D. 75% + 2.5%

Solution:

77. The part of the wireless system’s infrastructure that controls one or multiple cell sites’ radio signals, thus reducing the load on the switch

• A. Home Location Register
• B. Visitor Location Register
• C. Base station controller
• D. Base Transceiver Station

Solution:

78. Which feature of a “stealth” aircraft is most responsible for its low observability?

• A. Multi-faceted surfaces
• C. Minimal use of metals in airframe
• D. Large RCS

Solution:

79. What is the lowest modulation index at which an FM carrier is suppressed?

• A. π (3.1416)
• B. 2.40
• C. Only AM carriers can be suppressed
• D. 2π

Solution:

80. A global system for mobile communications-based PCS network used outside of the U.S.

• A. GSM
• B. EDGE
• C. CNETZ
• D. DCS 1800

Solution:

81. The splitting of a spectrum license into two or more licenses of fewer frequencies

• A. Band reduction
• B. Disaggregation
• C. Allocation
• D. Splitting

Solution:

82. What circuit function is found in all types of receivers?

• A. BFO
• B. An RF amplifier
• C. A detector
• D. An audio filter

Solution:

83. Which phone standard supports the highest data rate?

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

Solution:

84. _________is an analog modulation scheme in which the amplitude of a relatively high-frequency carrier signal is varied in accordance with the instantaneous amplitude of an information signal.

• A. Pulse Modulation
• B. QAM
• C. Angle Modulation
• D. Amplitude Modulation

Solution:

85. Entry of a designated frequency channel in the agreed plan, adopted by the ITU, for use by one or more nations for a terrestrial or space radio communication services in one or more identified countries or geographic areas and under specified conditions.

• A. Allotment
• B. Emission
• C. Allocation
• D. Assignment

Solution:

86. A TDR display shows a discontinuity 1.4 µs from the start. If the line has a velocity factor of 0.8 how far is the fault from the reflectometer?

• A. 16.8 m
• B. 168 m
• C. 325 m
• D. 32.5 m

Solution:

87. Introduced by AT&T Network Systems in 1991. Enables service providers to define, test and introduce new multimedia messaging, PCS and cell routing

• A. Packet Network
• B. Virtual Private Network
• D. Ethernet

Solution:

88. The standard operating system of a wireless network; technologies include AMPS, TDMA, CDMA and GSM

• A. Node B
• B. Unix
• C. Topology
• D. Air interface

Solution:

89. The Japanese standards-setting organization

• A. NTT (Nippon Telephone & Telegraph)
• C. Docomo
• D. JDC (Japanese Digital Cellular)

Solution:

90. The ________ is deflected horizontally and vertically to fill the screen area.

• A. permanent magnet
• B. yoke
• C. electron beam
• D. raster

Solution:

• A. 3
• B. 30,000
• C. 3,000
• D. 300,000

Solution:

92. Calculate the limit of visibility of an earth station at the equator, with the antenna pointing either west or east along the horizontal.

• A. 85.3°
• B. 88.3°
• C. 81.3°
• D. 84.3°

Solution:

93. What is a radar cross-section (RCS)?

• A. Target height and elevation
• B. A target’s reflection coefficient relative to a perfectly reflecting spherical surface of 1 m2 cross-section
• C. The plane through which a radar signal passes through a target
• D. An engineering isometric drawing showing a slice through the equipment rack(s)

Solution:

94. ________ adjustments cause the three electron beams to excite the correct colors on the screen.

• A. Comb
• B. Color
• C. Convergence
• D. Gamma

Solution:

95. Which of the following factors will affect the degree of diffraction when a train of water waves passes through a slit?

(1) The width of the slit

(2) The wavelength of the wave

(3) The amplitude of the wave

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)

Solution:

96. A fiber link is to be installed with the following characteristics:

Transmitter: laser diode with Pt = 1mW

Receiver: APD with minimum Pr = -57dBm

Tx/Rx port losses 6 dB each

Two connectors at 1 dB each

Five splices at 0.5 dB each

Fiber total loss 2 dB/km

Fiber total dispersion 0.505 ns/km

Maximum desired bit rate 35 Mbps

Determine the loss-limited line length for a loss margin of 5 dB

• A. 1.78 km
• B. 17.8 km
• C. 178 km
• D. 0.178 km

Solution:

97. Authorization given by a nation for a radio station to use a radio-frequency channel under specified conditions.

• A. Allotment
• B. Emission
• C. Allocation
• D. Assignment

Solution:

98. In FCC former designation, P2D means _________.

• A. Telegraphy; pulse-carrier tone-modulated
• B. Telephony; pulse-width modulated
• C. Telephony; amplitude-modulated pulses
• D. Telegraphy; pulse-width tone-modulated

Solution:

99. Crosstalk are considered to be intelligible to the listener when?

• A. At least 2 words are intelligible in 7-s period
• B. At least 7 words are intelligible in 4-s period
• C. At least 2 words are intelligible in 2-s period
• D. At least 4 words are intelligible in 7-s period

Solution:

100. A CDMA mobile measures the signal strength from the base as -100 dBm. What should the mobile transmitter power be set to?

• A. 250 mW
• B. 54 mW
• C. 320 mW
• D. 43 Mw

Solution:

Complete List of Communications Engineering Exams: ECE Pre-Board

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