Communications Engineering Mastery Test 15: ECE Pre-Board
This is 100 items set of Practice Examination 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
- A. Adaptive power control
- B. Pre-emphasis
- C. Level down
- D. Power attenuation
ANS: A
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
ANS: C
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%
ANS: D
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
ANS: C
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
ANS: B
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
ANS: B
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
ANS: B
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
- C. Rad
- D. Rem
ANS: A
9. A combination of two or more integrated circuits on one module
- A. PCB
- B. Combo chip
- C. TTL
- D. Chip set
ANS: D
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
ANS: C
11. A pen-based tablet computer used on a wireless local area network
- A. node
- B. source
- C. thin client
- D. master
ANS: C
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
ANS: D
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
ANS: D
14. How many electron beams actually leave the electron gun of a single-gun color CRT?
- A. 1
- B. 2
- C. 3
- D. 4
ANS: C
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
ANS: B
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
ANS: D
17. A permanent-magnet ring on the neck of the tube is used for ________.
- A. scanning
- B. centering
- C. deflecting
- D. focusing
ANS: B
18. The IS-95 CDMA standard developed by Qualcomm Inc
- A. WCDMA
- B. IMT-DS
- C. cdmaOne
- D. IMT-SC
ANS: C
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
ANS: A
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
ANS: A
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
- C. Overhead channel
- D. Message channel
ANS: A
22. In which ITU region is Philippines?
- A. ITU Region 1
- B. ITU Region 2
- C. ITU Region 3
- D. ITU Region 4
ANS: C
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
ANS: D
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
ANS: B
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
ANS: B
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
ANS: A
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
ANS: D
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
ANS: C
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
ANS: B
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
ANS: D
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
ANS: D
32. A method of taking signal strength measurements in a cellular coverage area
- A. radio sounding
- B. drive test
- C. boresighting
- D. field strength
ANS: B
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
ANS: A
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
ANS: C
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
ANS: B
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
ANS: B
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
ANS: B
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
ANS: A
39. In which semiconductor technology are the majority of cellphone PAs manufactured?
- A. GaAs/InGaP
- B. GaN
- C. SiGe
- D. Si/SiCMOS
ANS: A
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
ANS: D
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
ANS: B
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
ANS: B
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
ANS: D
44. A wireless phone programmed with stolen or duplicated electronic serial and mobile identification numbers
- A. RAID
- B. Backup
- C. Clone
- D. Party line
ANS: C
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
ANS: D
46. Fourier analysis often allows complex signals to be express as a series of __________.
- A. sinusoids
- B. pulse
- C. ellipse
- D. rectified signals
ANS: A
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
- A. Deadspot
- B. Footprint
- C. Hotspot
- D. Cell
ANS: D
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
ANS: B
49. Who is known as ”The Father of Radar?”
- A. Walter Eugene O'Reilly
- B. Albert Einstein
- C. Oliver Heaviside
- D. Robert Watson-Watt
ANS: D
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
ANS: B
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)
ANS: A
52. Using a wide-bandwidth channel for voice, data and/or video services
- A. Bandwidth
- B. Broadband
- C. Narrowband
- D. Baseband
ANS: B
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
ANS: C
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
ANS: B
55. Computer systems to help dispatch personnel and vehicles, commonly used by public-safety agencies
- A. Public Address System
- B. Public wireless amplifier
- C. Mobile broadcasting
- D. CAD (computer-aided dispatch)
ANS: D
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
ANS: C
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
ANS: C
58. Telephones, PBXs and other communications devices located in the home or office
- A. Terminal Adapter (TA)
- B. Terminal Equipment (TE)
- C. CPE (Customer Premise Equipment)
- D. MUX (Multiplxer)
ANS: C
59. Slang term for someone who breaks an encrypted computer code or circuitry
- A. Programmer
- B. Cracker
- C. Engineer
- D. Hacker
ANS: B
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
ANS: C
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.
ANS: B
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
ANS: C
63. Synthetic Aperture Radar (SAR) radar is mostly likely to be located on which platform?
- A. Airplane
- B. Ship
- C. Ambulance
- D. Police car
ANS: A
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)
ANS: C
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
ANS: C
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
ANS: C
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
ANS: D
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
ANS: A
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
ANS: B
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
ANS: D
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
ANS: C
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
ANS: C
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
ANS: C
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
ANS: A
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
ANS: C
76. What is the carrier level for blanking?
- A. 67.5%
- B. 12.5% + 2.5%
- C. 100%
- D. 75% + 2.5%
ANS: D
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
ANS: C
78. Which feature of a “stealth” aircraft is most responsible for its low observability?
- A. Multi-faceted surfaces
- B. Radar absorbent paint
- C. Minimal use of metals in airframe
- D. Large RCS
ANS: B
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. 2Ï€
ANS: B
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
ANS: D
81. The splitting of a spectrum license into two or more licenses of fewer frequencies
- A. Band reduction
- B. Disaggregation
- C. Allocation
- D. Splitting
ANS: B
82. What circuit function is found in all types of receivers?
- A. BFO
- B. An RF amplifier
- C. A detector
- D. An audio filter
ANS: C
83. Which phone standard supports the highest data rate?
- A. GPRS
- B. iDEN
- C. GSM
- D. EDGE
ANS: D
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
ANS: D
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
ANS: A
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
ANS: B
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
- C. Advanced intelligent network
- D. Ethernet
ANS: C
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
ANS: D
89. The Japanese standards-setting organization
- A. NTT (Nippon Telephone & Telegraph)
- B. ARIB (Association of Radio Industries and Businesses)
- C. Docomo
- D. JDC (Japanese Digital Cellular)
ANS: B
90. The ________ is deflected horizontally and vertically to fill the screen area.
- A. permanent magnet
- B. yoke
- C. electron beam
- D. raster
ANS: C
91. A mask for dot trios has about ____ holes.
- A. 3
- B. 30,000
- C. 3,000
- D. 300,000
ANS: D
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°
ANS: C
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)
ANS: B
94. ________ adjustments cause the three electron beams to excite the correct colors on the screen.
- A. Comb
- B. Color
- C. Convergence
- D. Gamma
ANS: C
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)
ANS: A
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
ANS: B
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
ANS: D
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
ANS: A
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
ANS: D
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
ANS: A