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ANSWER KEY IN PRE-TEST
1. A trunk is ___a. The base of a
communication towerb. A line connecting oe
telephone set to the PABXc. The structure where
antennas are attachedd. A telephone line connecting
two Cos
2. The simplest form of coding is __________.
a. Diphase b. Hybridc. Compressedd. Lineare. Quadratic
3. Whether or not polarization of an antenna is linear depends on __________.
a. Changes in direction in which the electric plane is radiated.
b. The direction in which the electric plane is radiated.
c. The horizontal or vertical plane of the electric wave
d. The direction in which the magnetic wave is radiated
4. In practice, the transmission lines are most connected to antennas that have a _______.
a. Resistive load whose resistance is greater than the characteristics impedance of the line
b. Resistive load whose resistance is less than the characteristic impedance of the line
c. Resistive load at the resonant frequency
d. Capacity Load
5. Sampling the analog wave produces _________.
a. Impulse Noiseb. Phase Distortionc. Pulse Amplitude Modulationd. Frequency Coherence
6. When the transmission line is matched to the load, it _______.
a. Transfers maximum current to the load
b. Transfers maximum voltage to the load
c. Transfers maximum power to the load
d. Reduces the load current
7. The equation f > 2BW is known as _________.
a. Shannon Theoremb. Nyquist Criterionc. Erlang Lawd. Edison Effect
8. Waveguide is a ________.a. Device used to determine
the wavelength of a signalb. Hollow metal tube used for
transmission of Microwave Energy
c. Plastic tubular transmission line for high RF network
d. Braided wire used for transmission of HF
9. Memory is added to the telephone set to
a. Allow more digits to be dialed
b. Allow faster dialingc. Allow automatic redialing of
the last number dialedd. None of these
10. The value of the resistor creating thermal noise is doubled, the noise power generated is therefore ______.
a. Halvedb. Quadrupledc. Doubledd. Unchanged
11. What is the function of the diode rectifier bridge in the line circuit of a telephone?
a. Lower the voltage to the telephone electronics
b. Raise the voltage to the telephone
c. Short out the line when the set is on-hook
d. Protect the set against polarity reversals on the line
12. Satellite that orbit in a circular pattern with an angular velocity equal to that of the earth is __________.
a. Geostationaryb. Early Bird Ic. Syncom Id. Stationary Satellite
13. Between two quantizers, the quality of one with the lower Signal to Quantizing Noise Ratio (SQR) will be ________.
a. Higherb. Lowerc. The samed. Not measurable
14. The signal path from transmitter to satellite is __________.
a. Uplink Signalb. Reflected Signalc. Incident Signald. Downlink Signal
15. If the code is only 4-bits for a T-1 system with a frame of 193 bits, how many channels can be transmitted?
a. 48b. 64c. 6d. 24
16. Which office class is the local central office?
a. 2b. 3c. 4d. 5
17. What bad electrical effect happens when the switchook is opened?
a. A high voltage transient is generated
b. The line is shorted outc. The line is openedd. No bad effects happen
18. The _________ angle measures the satellite position clockwise from the direction of true North is
a. Azimuthb. Elevationc. Depressiond. Critical
19. If the code word is 4 bit for T-1 system with a frame of 193 bits, what is the bit rate in mbps?
a. 0.722b. 3.008c. 1.544d. Coverage Area
20. The earth’s area that the satellite can receive from or transmit to is ______.
a. Footprintb. Primary Areac. 1.544d. 1.024
21. The most common carrier frequencies used for satellite communications are ________.
a. 6/4 and 14/12 GHz Bandsb. 8/6 and 16/14 GHz Bandsc. 20/18 and 28/26 GHz
Bandsd. 12/10 and 18/16 GHz
Bands
22. It represents energy that has neither been radiated into space nor
completely transmitted. a. Standing Wavesb. Captured Wavesc. Incident Wavesd. Modulated Waves
23. The signal path from satellite to earth-based receiver is ___________.
a. Downlink Signalb. Uplink Signalc. Incident Signald. Reflected Signal
24. _____________ refers to the ratio of phasor fields E and H for a plane (TEM) wave in an unbounded medium.
a. Wave impedanceb. Load impedancec. Intrinsic Impedanced. Characteristics Impedance
25. __________ is the quotient of maximum radiation intensity over the average radiation intensity.
a. Aperture gainb. Directivity gainc. Transmission gaind. Power gain
26. Another term for Amplitude Modulation (AM) is ___________.
a. Double Sideband Full Carrier (DSBF)
b. Single Sideband Suppressed Carrier (SSBC)
c. Frequency Modulation (FM)d. Pulse Code Modulation
(PCM)
27. Fold-over distortion of aliasing is _______________.
a. Eliminated by filtering out frequencies below 300 Hz
b. Another name for Crosstalkc. The Presence by Spurious
Frequencies caused by having high frequencies in the sampled signal
d. Eliminated by using Twisted Wires
28. A pulse Amplitude Modulator uses a modulating signal whose frequency is 3 KHz maximum. The practical sampling frequency is ________.
a. 6 KHzb. 7.25 KHzc. 2.5 KHzd. 3 KHz
29. The main purpose of a 19 KHz pilot in a stereo multiplexed signal in FM
is for the receiver to ______.a. Indicate stereo receptionb. Demodulate c. Modulated. Overmodulate
30. ______________ is an operation performed at the transmitter to achieve efficient and reliable information transmission.
a. Transmissionb. Filteringc. Modulationd. Multiplexing
31. Another name for multiplier circuit is ______.
a. Balanced modulatorb. Discriminatorc. Clipperd. Integrator
32. A process that uses the orthogonality of sines and cosines that makes possible to transmit and receive to different signals simultaneously on the same carrier frequency is:
a. Time Division Multiplexing (TDM)
b. Frequency Division Multiplexing (FDM)
c. Quadrature Multiplexingd. Duplexing
33. One section in a D-1 channel bank handles _________ voice channels
a. 12b. 20c. 24d. 48
34. The information of an AM signal resides in the
a. Upper Sideband Onlyb. Lower Sidebandc. Upper and Lower Sideband
onlyd. Carrier Signal
35. The process of varying some characteristics of high frequency sine wave in accordance with the variation of the modulating signal is called ______.
a. Communicationb. Propagationc. Restorationd. Modulation
36. Best HF radio communications between two distant countries is achieved when the F-1 and F-2 layers of the ionosphere recombine and other layers disappear during _____________.
a. Night timeb. Noon timec. Break timed. Both a and b
37. Cellular mobile telephone service ___.
a. Uses many low power transmitters with computer control rather than a few high power transmitters
b. Is a concept of improving frequency utilization by restricting users to a single or home area called a cell
c. Is another name of IMTSd. Uses high power
transmitters
38. ___________ is the sound energy per unit area at right angles to the propagation direction per unit of time.
a. Sound stressb. Coherencec. Sound Intensityd. Loudness
39. A _____ filter passes the lower frequency portion of a signal but attenuates the higher frequency portion of the same signal.
a. Low Passb. High Passc. Band Stopd. Band Pass
40. Modulation is used to __________.a. Increase the carrier powerb. Reduce the bandwidth usedc. Allow the use of practical
antennasd. Shorten the transmission
channel
41. In radio communication the maximum permissible departure by the center frequency of the frequency band occupied by an emission from assigned channel or, by the characteristic frequency of an emission from the reference frequency __________.
a. Frequency Toleranceb. Assigned Frequencyc. Frequency Bandwidthd. Center Frequency
42. A pre-emphasis circuit improves the signal-to-noise ratio of an FM signal by _____.
a. Amplifying the higher audio
frequenciesb. Boosting the bass
frequenciesc. Amplifying the whole
frequency bandd. Increasing the carrier power
43. A superheterodyne receiver with an IF of 455 KHz is tuned to a signal to 1100 KHz. The image frequency is ____.
a. 645 KHzb. 910 KHzc. 1555 KHzd. 2010 KHz
44. Grounding resistance should be kept as low as possible and should not exceed _______ ohms for outside plant telephone poles, manholes and customer premises
a. 5b. 25c. 0d. 50
45. In a communications system, noise is most likely to affect the signal ______.
a. At the transmitterb. In the channelc. In the information sourced. At the destination
46. In a standard TV broadcast channel, the AM picture carrier signal is
a. 0.25MHzb. 0.6MHzc. 1.25MHzd. 4MHze. 3.75MHz
47. Frequencies in the UHF range propagate by means of __
a. Ground wavesb. Surface wavesc. Sky wavesd. Space waves
48. In superheterodyne receivers, refers to the erroneous frequency difference resulting in an incorrect frequency being fed to the IF amplifier
a. Crosstalkb. Crosslinec. Intermodulationd. Mixing errore. Tracking errorf.
49. The ground wave eventually disappear as it moves farther away from the transmitter, because of
a. Diffractionb. Interference from skywave
c. Refractiond. Reflectione. Tilting
50. An amplifier has an input of 100mW and an output of 10W. The gain is ___
a. 10b. 20c. 50d. 100e. 200
51. As electromagnetic waves travel in free space, only one of the following can happen to them
a. Absorptionb. Attenuationc. Refractiond. Reflection
52. A matched tapping device for insertion in a CATV cable which introduces a loss of only 1 dB in the through transmission and provides a spur outlet
a. Attenuatorb. Directional couplerc. F-connectord. splittere. T-pad
53. The standard reference antenna for the directive gain
a. Elementary dipoleb. Half-wave dipolec. Hertzian dipoled. Isotropic antennae. Infinitesimal dipole
54. A process applied to a multiple signal for recovering signals combined within it and for restoring the distinct individual channels of these signals
a. De-emphasizingb. Detectionc. Demultiplexingd. Modulation
55. One example of a nonresonant antenna
a. Disconeb. Folded dipolec. Hertz antennad. Marconi antennae. Rhombic antenna
56. Space diversity transmission means transmitting and receiving on__
a. 2 or more different frequencies
b. 2 or more antennas operating on different frequencies
c. 2 or more antennas operating on the same frequency
d. 2 or more identical
frequencies
57. An antenna that is circularly polarized
58. Losses in optical fibers is not caused by___
a. Glass attenuationb. Impuritiesc. Microbendingd. Tyndall dispersione. Stepped index operation
59. EIRP is the actual power radiated by the antenna multiplied by the ___ of the antenna
a. Isotropic power gainb. Free space lossesc. Lengthd. Losse. K factor
60. Known as muting or quieting is a device that cuts off the output in the absence of a carrier to eliminate noise
a. Butterworth filterb. Echo cancellerc. Hybridd. noise limitere. squelch
61. When electromagnetic waves are propagated in a waveguide, they___.
a. Are reflected from walls but not travel along them
b. Travel along the broader walls of the guide
c. Travel along the 4 walls of the waveguide
d. Travel through the dielectric without touching the walls
62. Increasingly, new satellites operate in the Ku-band which are in the ___________ Ghz range.
a. 11 to 13b. 21 to 30c. 11 to 14.5d. 4 to 6
63. Noise that is non-continuous, consisting of irregular pulses or noise spikes of short duration with high amplitudes.
a. White noiseb. Thermal noisec. Galactic noised. Impulse noise
64. A communication network used by one organization over a limited distance that allows users with PCs
to be linked together and share information and resources is called ________.
a. Timesharingb. LANc. Distributed processingd. WAN
65. How can absorptive fading happen?a. K-factorb. Rain attenuationc. Ductingd. Inversion
66. Simultaneous transmission of 2 or more signals over a single medium.
a. Full duplexb. Half duplexc. Full-full duplexd. Simplex
67. In telecommunications signaling concept, the status of the network in the presence of a demand and a connection is __________.
a. Busy hourb. Seizurec. Idled. Grade of service
e. Erasable Binary Coded Decimal Interchange
68. Echo is _____________.a. A signal of the same
amplitude but 180 degrees out of phase from the original and mixed with original signal at the transmitter to produce a more intelligible output signal
b. A wave which has been reflected or otherwise returned with sufficient magnitude and delay for it to be perceptible in some manner as a wave distinct from that directly transmitted
c. The signal having a higher frequency than the original and transmitted back to earth by a passive satellite
d. All of these
69. The slight lowering of resonant frequency due to small amount of capacitance presented by the insulators and wire loop that ties the insulator to the antenna is known as ______.a. Miller Effectb. Dellinger Effectc. End effectd. Ramsauer Effecte. Skin effect
70. The frequency range over which antenna operation is satisfactory and is generally taken between half power or 3 dB down points.
a. Bandwidthb. Beamwidthc. Polarizationd. Carrier Frequency
71. The property of an antenna that causes it to receive signals better than one direction than in others is _____.
a. Directivityb. Radiation Patternc. Reciprocityd. Front-to- Back Ratioe. Harmonic Operation
72. It shortens the physical length of antenna by an equivalent effect of adding capacitance in series with the antenna, reducing its totalcapacitive reactance.
a. Counterpoiseb. Top Hatc. Loading Coild. Microstripe. None of these
73. The digital to analog converter in a synchronous modem sends signals to the ____.
a. Modulatorb. Transmission Linec. Terminald. Equalizere. Tuner
74. A radiations system consisting of grouped radiators or elements placed close together to be within each other’s induction field to produce a certain radiation pattern.
a. Dipole Arraysb. Quarterwave Matchingc. Delta Matchingd. Parasitic Elementse. Quaggi
75. The gain of a parabolic antenna is influenced by the ____.
a. Aperture Ratiob. Capture Areac. Mouth Diameterd. Illumination Efficiencye. All of these
76. Which of the following transmission media is not readily suitable to CSMA operation
a. Radiob. Optical Fibersc. Coaxial Cabled. Twisted Pair
e. None of these
77. The core of an optical fiber has ___.a. A lower index of refraction
than airb. A lower index of refraction
than the claddingc. A higher index of
refraction than the cladding
d. Equal index of refraction to that of the cladding
78. At microwave frequencies, the LOS distance is sometimes extended through the occurrence of ___.
a. Ionospheric Reflectionsb. Fogc. Sporadic Ed. Dellinger Dropoutse. Ducting
79. The best system configuration to overcome multipath fading on “over-the water” propagation
a. Angle diversityb. Frequency diversityc. Non-diversityd. Space diversity
80. Layer 1 of the OSI model isa. Link layerb. Network layerc. Physical layerd. Session layer
81. Color TV is made possible through the combination of the primary colors of
a. blue, yellow, greenb. red, green, bluec. red, white , blued. white, red, green
82. A type of modulation technique that conveys audio information from one station to another by varying the carrier frequency at the audio rate
a. Amplitude modulationb. Frequency modulationc. Quadrature modulationd. Phase modulation
83. The applications layer of the OSI model is the
a. First layerb. Second layerc. Seventh layerd. Sixth layere. Third layer
84. Causes modulation either in its internal circuitry or in another associated circuit
a. Detectorb. Modulatorc. Multivibratord. Multiplexere. Phasor
85. The half-power points of the beamwidth of the front lobe of a
directional antenna is the point equal to
a. 0.707b. 0.636c. 0.318d. 0.5e. 1.414
86. A tuned amplifier uses___ loada. Capacitiveb. Inductivec. LC tankd. Resistive
87. When a single antenna is intended to be used for transmitting and receiving , it is necessary to use__
a. Combinerb. Diplexerc. Duplexerd. Multiplexere. Transponder
88. The receiver’s ability to receive both very weak and extremely strong stations without introducing distortion
a. Dynamic rangeb. Effective rangec. Figure of meritd. Sensitivitye. Selectivity
89. The T-1 North American digital system has 24 channels and require a transmission speed of
a. 64 kbpsb. 640 kbpsc. 960 kbpsd. 1.54 Mbpse. 2.048 Mbps
90. It a system which provides the longest digital transmission distances
a. Computer busb. Digital PBXc. Local area networkd. Voice band modem
91. When modulating frequency is disabled , the modulation index is halved, and the modulating voltage remains constant. The modulating system is __
a. Amplitude modulationb. Frequency modulationc. Phase modulationd. Pulse modulation
92. Which of the functions is not provided as part of the basic Ethernet design?
a. Access controlb. Addressingc. Automatic retransmissiond. Multiple virtual networks
93. The frequency the oscillator must be set at for an output of 95 kHz if the output of the oscillator is being fed to two frequency triplers connected in cascaded form
a. 6.3 MHz
b. 9.65 MHzc. 10.56 MHzd. 15.8 MHz
94. A resonant circuit contains ___ element
a. R and Lb. Only Rc. R and Cd. L and C
95. At resonance, a circuit behaves as a ___ load
a. Capacitiveb. Inductivec. magneticd. PN junctione. Resistive
96. Pre-emphasis and de-emphasis are used in the FM stereo multiplex system to improve__
a. Current ratiob. CMRRc. Power ratiod. Standing wave ratioe. Signal-to-noise ratio
97. At series resonance, the voltage across L is___ voltage across C
a. Equal to but in phase withb. Equal to out of phase withc. Greater than but in phase
withd. Less than but in phase with
98. Audio pitch refers to _________.a. Frequencyb. Harmonicsc. Amplituded. Phase
99. A characteristic of radio receiver to amplify a peak signal and produce a desirable intelligence at the output of the speaker.
a. Sensitivityb. Selectivityc. Reliabilityd. Fidelity
100. As the modulation level is increased, the carrier power ______.
a. Is increasedb. Is decreasedc. Remains the samed. Either a or b
1. The slight lowering of resonant frequency due to small amount of capacitance presented by the insulators and wire loop that ties the insulator to the antenna is known as ______.f. Miller Effectg. Dellinger Effect
h. End effecti. Ramsauer Effectj. Skin effect
2. According to the Philippine Electronics Code, the minimum allowable vertical clearance above the ground is at least ___ meters when wires are crossing or installed along public thoroughfares in urban areas.
a. 5.5b. 4.5c. 4.0d. 3.5e. 3.0
3. The frequency range over which antenna operation is satisfactory and is generally taken between half power or 3 dB down points.
a. Bandwidthb. Beamwidthc. Polarizationd. Carrier Frequency
4. According to this law, passing the Board Examinations administered by the PRC may be converted into equivalent Civil Service Eligibility to pass preparatory requirements for government service.
a. RA 1080b. PD 1081c. RA 184d. RA 3850e. RA 6511
5. The property of an antenna that causes it to receive signals better than one direction than in others is _____.
a. Directivityb. Radiation Patternc. Reciprocityd. Front-to- Back Ratioe. Harmonic Operation
6. According to the Philippines Electronics Code, grounding rods must take the shortest route connected directly to master ground bus or direct to earth without any intervening splices or sharp bends. The standard diameter for grounding rods is _____.
a. AWG Nr 10b. AWG Nr 2c. AWG Nr 33d. AWG Nr 12e. AWG Nr 16
7. ______ consists of radials supported above the ground and is used as a substitute for ground screen in areas of low conductivity.
a. Counterpoiseb. Grounding rodc. Lightning rodd. Spark-Gape. Top Hat
8. The scrambler in a synchronous modem is in the _____.
a. Control Sectionb. Receiver Sectionc. Transmitter Sectiond. Terminal Sectione. Antenna
9. Ungrounded antennas which are normally used for frequencies above 3 Megahertz are called ____.
a. Hertz Antennasb. Marconi Antennac. Yagi-Udad. LPDAe. Zepp Antenna
10. Binary codes are sometimes transformed in modems into ____.
a. Hexadecimalb. Huffman codesc. Gray coded. Complementary codese. Supplementary codes
11. It shortens the physical length of antenna by an equivalent effect of adding capacitance in series with the antenna, reducing its total capacitive reactance.
a. Counterpoiseb. Top Hatc. Loading Coild. Microstripe. None of these
12. The digital to analog converter in a synchronous modem sends signals to the ____.
a. Modulatorb. Transmission Linec. Terminald. Equalizere. Tuner
13. A radiations system consisting of grouped radiators or elements placed close together to be within each other’s induction field to produce a certain radiation pattern.
a. Dipole Arraysb. Quarterwave Matchingc. Delta Matchingd. Parasitic Elementse. Quaggi
14. ____ created the Board of Communications (BOC) which became the first quasi- judicial body with adjudicatory powers on matters involving telecommunications services.
a. RA 1476
b. Integral Reorganization Law of 1972
c. EO Nr 546d. PD 55e. PD 1081
15. A multi- element antenna in which all the elements are excited through a transmission line _____.
a. Driven Arrayb. Parasitic Arrayc. Phased Arrayd. Loop Arraye. None of these
16. _________ integrated the Telecommunications Bureau created in 1974 and the Board of Communications into one entity now known as the National Telecommunications Commission, under the administrative control of the Ministry of Transportation and Communications and was empowered to supervise, adjudicate and control all telecommunications services throughout the country.
a. E.O. 546b. RA 3846c. RA 5734d. E.O. 109e. E.O. 125
17. In an antenna array, the ___ elements are not connected to the transmitter output, rather, the elements obtain their power through coupling to another element and they may act as reflectors or directors.
a. Parasiticb. Drivenc. Compoundd. Complexe. None of these
18. According to the Philippine Electronics Code, the minimum threshold current (in RMS) in a circuit whereby ventricular fibrillation will most likely occur is ____ and may therefore be classified as hazardous to humans whose wet skin resistance is about 1500 Ohms.
a. 0.030 Amperesb. 300 Amperesc. 30 Amperesd. 3 Amperes e. None of these
19. A parasitic element which is longer than the driven element in an antenna array and acts like a concave mirror is called _____.
a. Reflectorb. Directorc. Collimator
d. Phasore. None of these
20. To prevent hazards of electric shock, what protection method/s must an ECE use?
a. Shielding and Groundingb. Voltage Limitingc. Direct Bonding, Surge
Arresterd. Discharge Gaps and Fusee. All of these
21. A linear antenna array whose arrangement consists of a number of dipoles of equal size, equally spaced along a straight line with all dipoles fed in the same phase from the same source and whose radiation is towards the side of the array.
a. Broadside Arrayb. Endfire Arrayc. Phased Arrayd. LPDAe. None of these
22. Acoustic shock results from abnormally high sound level, the physical effects of which may vary from minor discomfort to serious injury. The amplitude of sound pressure must not exceed ____ above 2x 10-4 microbar at 1000 Hertz reference tone.
a. 0 dBb. 30 dBc. 33 dBd. 120 dBe. 200 dB
23. A single turn coil consisting of 2 elements, one is directly fed and the other conductively coupled at the ends. It carries RF current mostly in phase and has an impedance of 300 Ohms, almost four times that of a Hertz dipole.
a. Folded Dipoleb. Yagi- Udac. Quaggid. Zepp Antennae. Discone Antenna
24. According to the Philippine Electronics Code, the average resistance of a dry adult human body is about ___.
a. 1 MegOhmb. 1500 Ohmsc. 1 KiloOhmd. 2 KiloOhmse. None of these
25. The gain of a parabolic antenna is influenced by the ____.
a. Apperture Ratiob. Capture Areac. Mouth Diameter
d. Illumination Efficiencye. All of these
26. Refers to the set of rules and regulations of the construction, installation, establishment operation of radio stations and the possession, ownership, manufacture, purchase, sale and transfer of transceiver
a. DO Nr. 88b. DO Nr. 11c. DO Nr.69d. Do. Nr.55e. DO Nr. 33
27. The effective area of the parabolic reflector calculated from power receiver in comparison with the power density of the received signal
a. Capture areab. Collimation factorc. Edge taperd. Front-to-back ratioe. Spill-over
28. In the code of professional ethics and conduct, the moral philosophy guiding the ECE are
a. Courage, integrity and loyalty
b. Duty, country and honorc. Honesty, justice and
courtesyd. Duty, honor and loyalty
29. A type of feed mechanism to improve the directivity of a parabolic antenna whereby a hyperboloid secondary reflector is used and rays from the feedhorn are reflected from paraboloidal mirror which renders therays para;;e; or collimated to each other
a. Cassegrain feedb. Horn antennac. Offset paraboloidd. Small dipole arraye. Spherical reflector
30. The official seal of the ECE board has a diameter of 1 and 7/8 inches. It is composed of the markings”Electronics and Communications Engineering Board of Examiners” except
a. Atoms and electronsb. Circumferential dots and
dashesc. Lightningd. Satellite antenna
31. Microwave antennas used for frequencies 10 Gigahertz and above, collimates and straightens out wavefronts by greatly slowing down the portion of the wave in the center
a. Cass-hornb. Conical hornc. Hog hornd. Lens antennase. Skeptical horn
32. This law requires radio franchise and certificate of public convenience and necessity (CPCN) for the operation of communications utilities, wire or wireless telephone or telegraph systems and other similar public telecommunications utilities
a. EO 546 of 1979b. DO 88 of 1988c. RA 3846 of 1931d. RA 3850e. DO 11 of 1951
33. The function of a lens antenna is to ensure that signals are in phase after they have passed through the antenna. For lower microwave frequencies or strongly curved wavefronts, problems of excessive thickness and absorption of large portion of radiation is experienced in lens antenna. This problem of thickness is solved by___
a. Focusingb. Jumpingc. Steppingd. Zoning
34. The receive equalizer in a synchronous modem
a. Adaptiveb. Compromisec. Impairmentd. Statisticale. terminator
35. A type of antenna used for broadband VHF /UHF transionospheric communications and has circular polarization
a. Antenna arrayb. Cass hornc. Disconed. Helical antennae. Parabolic antenna
36. Otherwise known as “Ship Radio Station Law”
a. RA 3396b. RA 3846c. RA 5734d. RA7925e. RA1476
37. An antenna array consisting of a number of electrically connected dipoles of different lengths and spacing fed from 2 wire lines transposed between each adjacent pair of dipoles fed from the narrow end where maximum radiation occurs
a. Broadside arrayb. Endfire arrayc. Log periodic dipole
arrayd. Helical arraye. Quanggi
38. The receive equalizer reduces relay distortion using
a. Diode matrixb. Descramblerc. Difference engined. Gearshifte. Tapped delay line
39. In the XMODEM protocol, the sender waits for what character from the receiver before beginning transmission
a. ACKb. EOTc. NAKd. RVIe. WACK
40. The CCITT V.26 modem has a modulation rate of__
a. 1200 Hzb. 1200 baudsc. 1560 cpsd. 2400 kbpse. 6400bps
41. If each character in an XMODEM block has an ASCII value of 50, what would be the value of checksum added to the block?
a. 23b. 25c. 41d. 50e. 100
42. The transmission signal coding method used for T-1 carrier
a. Bipolarb. Binaryc. Hollerithd. Manchestere. NRZ
43. Which of the following is not a valid rule for XOR?
a. 0 XOR 0 =0b. B XOR B = 0c. 1 XOR 1 = 1d. A XOR A = 0e. 1 XOR 0 =1
44. Multiplexing is___a. The process of increasing
bandwidth on a channelb. Mailing letters at the Post
Officec. A technique which
enables more than one data source to share the use of a common line
d. The ability to share frequency by time
45. How many messages may be outstanding (unacknowledged ) on a BiSync kink?
a. 1b. 2c. 4d. 8e. 10
46. One of the reasons frequency division multiplexing has essentially been replaced by time division multiplexing is because:
a. There is more time than frequency
b. It is difficult to place channels side by side
c. Noise is amplified with voice when an FDM system is used
d. Most available frequencies have been used
47. Which code set is used in Bisync when using VRC/LRC but is not operating in transparency code?
a. EBCDICb. ASCIIc. SBTd. Field datae. Trellis Code
48. When the amplitude of pulses is varied to represent analog information, the method is called _____.
a. PCMb. PWM c. PAMd. PPMe. WDM
49. Which of the following transmission systems provide the highest data rate to an individual device?
a. Voice Band Modemb. Local Area Networkc. Computer Busd. Digital PBXe. None of these
50. The PCM sampling rate is 8000 samples per second because ____.
a. That represents the maximum rate technology supports
b. This rate allows unique values
c. This rate allows the faithful reconstruction of an analog signal
d. This rate is easily produced by a sampling chip
51. The data rate of the ISDN Basic Access B channel is ____.
a. 32 kbpsb. 64 kbps
c. 144 kbpsd. 192 kbpse. None of these
52. In general, digital transmission provides a higher level of signal quality than analog transmission because ____.
a. Repeaters regenerate digital pulses and remove distortion while amplifiers increase an analog signal, including any prior signal distortion.
b. Digital signals are smaller than analog signals and cannot be easily distorted.
c. Analog signals are continuous and are not easily distorted.
d. Digital signals are easier to sample than analog signals
e. Both (b) and (d)53. The data rate of the IDSN Basic
Access D channel is _____.a. 64 kbpsb. 16 kbpsc. 8 kbpsd. 144 kbpse. 356 kbps
54. The D-4 framing pattern contains a sequence of ____.
a. 24 bitsb. 4 terminal and 8 framing
bitsc. 8 terminal and 4 framing
bitsd. 12 bitse. 36 bits
55. The equation that defines the composition of an ISDN Basic Access Line is____.
a. 2B + Db. B+ Dc. B+ 2Dd. 2B+ 2De. 3B + 4D
56. Bipolar signaling is used in place of unipolar signaling on T-1 lines because _____.
a. Bipolar produces twice as many marks as a unipolar signal
b. It allows transmission at polar locations
c. It allows transformers to be spaced far from one another which reduces the cost of transmission
d. Bipolar signaling reduces residual voltage build- up, allowing a digital signal to be
separated from power through the use of a transformer.
e. None of these57. In North America, the equation
that defines the composition of an ISDN Primary Access line is ____.
a. 30B +Db. 2B +Dc. B + Dd. 23B + De. 35 B+ 6D
58. B7 Zero Code Suppression is a technique which ____.
a. Allows data to flow on a digital line
b. Ensures each byte has at least one mark bit
c. Is the latest clear channel encoding technique developed by Bell Laboratories
d. Provides clear channel transmission capability allowing 64 kbps data transmission on a voice channel
e. None of these59. Which of the following systems
provides the longest digital transmission distances?
a. Parallel transmissionb. Unlimited Expansionc. Low cost access for low
bandwidth channelsd. Application independent
interfacese. None of these
60. International bipolar violations _____.
a. Represent coding errors caused by line impairments
b. Result in successive marks having opposite polarities
c. Are used to convey information or maintain a minimum number of ones on a digital line.
d. Occur only in laboratoriese. Occur at the North and
South Poles simultaneously
61. Which of the following transmission media is not readily suitable to CSMA operation
a. Radiob. Optical Fibersc. Coaxial Cabled. Twisted Paire. None of these
62. Demultiplexing by a Time Division Multiplexer occurs based on ___.
a. The position of data within a frame
b. The position of a frame within a group of frames
c. The activity of a connected device
d. The priority assigned to a connected device
63. Which of the following functions is not provided as part of the basic Ethernet design?
a. Access Controlb. Addressingc. Automatic Message
Retransmissiond. Multiple Virtual Networks
64. The requirements for a successful transmission system using light are ___.
a. Powerful, reliable light source
b. Strong glassc. Reliable, low cost
transmission mediumd. Powerful amplifiese. Both (a) and (c)
65. Which of the following is not a useful property of a Manchester line code for an Ethernet?
a. Continuous Energyb. Continuous Clock
Transitionsc. No DC Componentd. No signal change at 1 to
0 transitione. All of these
66. The core of an optical fiber has ___.a. A lower index of refraction
than airb. A lower index of refraction
than the claddingc. A higher index of
refraction than the cladding
d. Equal index of refraction to that of the cladding
67. The network interface that will permit equipment without an ISDN interface to be connected into an ISDN interface is known as ____.
a. TE-1b. TE-2c. TAd. TM-1e. TM-2
68. For single- mode fibers, the core diameter is about ____.
a. 10 times the Fiber Radiusb. 3 times the wavelength
of light carried in the fiber
c. 15 Micrometers
d. 10 times the wavelength of the light carried in the fiber
69. Which of the following data communications functions is generally provided for in a LAN?
a. Data Link Controlb. Applications Processingc. Flow Controld. Routinge. None of these
70. Over a period of 30 years, a kilometer of fiber optic cable is likely to be broken ____.
a. Not at allb. Oncec. 10 timesd. 2 or 3 timese. None of these
71. The purpose of the preamble in an Ethernet is____.
a. Clock Synchronizationb. Error Checkingc. Collision Avoidanced. Broadcaste. None of these
72. Deposition of dopants on fiber performs is done by__
a. Axial depositionb. Inside vapor depositionc. Outside vapor depositiond. All of these
73. Which of the following is possible in a token-passing bus network?
a. In-service expansionb. Multiple time divisionc. Unlimited number of
stationsd. Unlimited distances
74. A light emitting diode is able to couple how much power into an optical fiber?
a. 10 wattsb. 10 Milliwattsc. 100 microwattsd. 1 picowatte. 1 watts
75. A LAN architecture which can be expanded to the greatest total system bandwidth
a. Broadband cable systemb. CSMA/CD basebandc. Digital PBXd. Token-passing network
76. Avalanche photodiode receivers can detect bits of transmitted data by receiving
a. 1 photonb. 10 photonsc. 100 photonsd. 200 photonse. 1000 photons
77. The number of channels on which different operations can occur simultaneously on one ISDN basic access line
a. 1b. 2c. 3d. 4e. 5
78. When the index of refraction is greater than material 1 than it is in material 2, the velocity of propagation in material 1 compared to material 2 is__
a. Equal to or greater thanb. Greater c. Lesserd. Equale. None of these
79. Which of the following systems is the most capable of servicing a wide range of applications?
a. Broadband cable systemb. CSMA/CD basebandc. Digital PBXd. Token-passing network
80. The different angles of entry of light into optical fiber where the diameter of the core is many times the wavelength of the light transmitted are called__
a. Emittersb. Modesc. Sensorsd. Refractorse. Reflectors
81. Digital telephones and integrated voice-data work stations are examples of this type of ISDN equipment
a. NT2b. TAc. TEd. TMe. TP
82. In a single-mode fibers, a large fraction of the power is propagated in the:
a. Airb. Claddingc. Junctions or splicesd. Sheathe. Core
83. A characteristic of toke passing ring as opposed to a token passing bus
a. Flexible polling interfaceb. Passive interfacec. Priority access capabilitiesd. Signal quality control
84. The loss in signal power as light travels down a fiber
a. Absorptionb. Attenuation
c. Propagationd. Scatteringe. Reflection
85. Not a motivation for digitizing a voice signal in the telephone of a digital PBX
a. Fewer wire pairsb. Lower cost telephonesc. Multiplexed voice and
data channelsd. Simplified control
signaling86. The coupling efficiency of an LED
light source to an optical fiber with a numerical aperture of 0.2 or more is
a. 0.1%b. 2%c. 10%d. 30%e. 60%
87. The electrical state of the control leads in a serial interface is a concern of__
a. Link layerb. Data link layerc. Physical layerd. Network layer
88. The FT 3C light wave system contains the following number of fibers__
a. 12b. 64c. 128d. 144e. 256
89. Not a characteristic of the hub architecture of ARCnet
a. Directionalized transmission
b. RIM port isolationc. Zero insertion loss
amplifiersd. Alternative routing
90. A geostationary satellite used for communications systems is not/does not__
a. Remains stationary relative to earth’s surface
b. Rotates with the earthc. Stationary in the sky
91. The X.25 standard specifies a__a. Data bit rateb. DTE/DCE interfacec. Technique for dial accessd. Technique for start-stop
data92. Multiple repeaters in
communications satellites are known as__
a. Detectorsb. Diplexersc. Modulatorsd. Stations
e. transponders93. The transmission of data on an
ISDN line between a customer’s premises and a carrier central office is encoded using__
a. 2BIQ encodingb. Hexadecimal encodingc. BCH encodingd. Octal encodinge. QAM
94. The bandwidth required to send 132 voice-grade channels by FDM on an international satellite system
a. 10 MHZb. 50MHZc. 500MHzd. 1320 MHze. 22.5GHz
95. The X.25 standard is__a. Complete description of a
public data networkb. Required for all packet
switching networksc. A recommendation of
the CCITTd. Used by all packet
terminals96. Communications protocols
always have a____a. BCC b. Start-stop bitsc. Set of symbolsd. Start of headere. Special flag symbols
97. Cannot be provided in broadband LAN
a. CCTVb. Frequency agile modemsc. Fiber optic
transmissionsd. Voice circuits
98. The Baudot Code uses how many bits per symbol
a. 4b. 5c. 7d. 8e. 9
99. Not possible in a digital(data) PBX using twisted pair transmission
a. Computer port concentration
b. 64 kbps circuitsc. High speed file transfersd. Transmission up to
several thousand feet100. When transmitting odd
parity coded symbols, the number of bits that are zeroes in each symbol is:
a. Evenb. Oddc. Unknown
d. None of these101. The electrical state of the
control leads in a serial interface is a concern of the ___layer protocol
a. datab. Linkc. Networkd. Physicale. Session
102. The Hamming distance between the characters 1001101 and 1011011
a. 0b. 1c. 2d. 3e. 4
103. Not considered a primary objective of data networking
a. Accuracyb. Packet switchingc. Securityd. Timeliness
104. Radiation of electrical energy is practicable only above__kHz
a. 5b. 10c. 30d. 12e. 15
105. The X.25 standard specifies a__
a. Data bit rateb. DTE/DCEc. Technique for dial accessd. Technique for start-stop
data106. Which of these statements
is false? Convolutional codes ___a. Are a form of block codeb. Are also called recurrent
codec. Are used with forward
error correctionsd. Depend on both current
characters to be encoded and those that have been endoded previously
107. On a point-to-point data channel using an analog circuit, transfer rate of information bits(TRIB) is___
a. Equal to the modem bit rate
b. Lower than the modem bit rate
c. Not related to the modem bit rate
d. Higher than the modem bit rate
108. Modulation is done in___a. The antenna
b. Between transmitter and receiver
c. Radio receiverd. Transmitter
109. The X.25 standard is___a. A recommendation of the
CCITTb. A complete description of
a public data networkc. Required for all packet
switching networkd. Used by all packet
terminals110. Type of CRT-based
terminals most closely resembles the KSR teletypewriter configuration
a. Buffered terminalb. Bus terminalc. Dumb terminald. Smart terminale. Terminal island
111. The block length that gives maximum TRIB___
a. Decreases as the error rate increases
b. Increases as the error rate increases
c. Is not related to error rated. Is called the optimum
block length112. In a radio transmitter__ is
used.a. Colpitts Oscillatorb. Crystal oscillatorc. Hartley oscillatord. RC phase –shift oscillatore. Wien –bridge oscillator
113. The X.25 for packet network is analogous to___
a. Local loop standards for a telephone network
b. Handset standards for a telephone
c. PBX for a telephone network
d. Switching standards for a telephone network
114. Not generally used as a stand-alone data communication terminal
a. Magnetic media transceivers
b. Mainframe computersc. Microcomputerd. Minicomputer
115. Smart TDMsa. Are always better than
FDMb. May be better than dumb
TDMs if the data terminals have a low duty cycle
c. Are always better than dumb TDMs
d. Are the same as modems sharing devices
116. In an AM wave, useful power is carried by___
a. Both sidebands and carrier
b. Carrierc. Sidebandsd. None of these
117. The value of the “A” field in a LAPB frame specifies_____
a. The calling DTE for a virtual call
b. The data sink for a VC or PVC
c. The called DTE for a virtual call
d. One of the two ends of a serial interface
118. Which of the following standards or organizations produce standards which are NOT generally used in the US?
a. ANSIb. CCITTc. ISOd. UL
119. FDM devices can operatea. Like modem sharing
devicesb. On multipoint analog data
channelsc. More efficiently than
dumb TDMsd. More efficiently than
smart TDMs120. In this wave phenomenon,
each little parcel of air vibrates in some fashion and passes on the disturbance to its neighbors
a. Electromagnetic interference
b. Lightc. Magnetic fieldd. Sound
121. A group of packets from a source through an X.25 jacket system to a sink___
a. Arrive in the same order send for VC, but not for PVC
b. Arrive in the same order for PVC but not for VC
c. Arrive in the same order for both PVC and VC
122. The difference between synchronous and asynchronous data transmission can beobserved by noting___
a. How accurate the clock isb. How fast the data is
transmitted on the circuitc. When start and stop
pulses are used
123. Protocol converters are___a. The same as multiplexersb. Same as TDMs c. Usually operated in pairsd. Usually not operated in
pairs124. In this situation, a
significant amount of sound energy is literally lost
a. Absorptionb. Condensationc. Radiationd. Sublimatione. Vibration
125. A protocol is a set of rules governing a time sequence of events that must take place___
a. Across an interfaceb. Between nonpeersc. Between peersd. Between superiors
126. Some characteristics of the EBCDIC code are___
a. It is binary coded decimal code expanded to allow the transmission of letters and control characters
b. EBCDIC can easily be transformed into ASCII-8 by adding hexadecimal constant to the ASCII-8 code
c. It is used exclusively on OBM computers
127. Null modems area a type of___
a. Demultiplexerb. Multiplexerc. Modemd. Modem eliminatore. Protocol converter
128. Distinctly spaced reflection are discrete and perceptible
a. Diffuse reflectionb. Echoc. Irregularityd. Non-linear effectse. Reverberation
129. The OSI Reference Model defines the functions for seven layers of protocols____
a. Including the user and communications medium
b. Including the communications medium but not the user
c. Not including the user or communications medium
d. Including the user but not the communications medium
130. Which of the following techniques will not help to correct transmission line errors?
a. Algorithmic conversionb. Checksumc. N of M codesd. Parity checking
131. A basic technique for isolating data communication faults is____
a. Calling the DTE service department
b. Calling telephone company
c. Performing a loopback test
d. Simulating the system on a special purpose computer
132. What transient beginning or ending is generated when a steady sound source is turned ON or OFF?
a. Early reflectionb. Diffuse reflectionc. Impulsive soundd. Reverberant sound
133. The X.25 standard covers how many OSI layers?
a. Threeb. Fourc. Sevend. Ten
134. The primary consideration when designing an error control system for data communications is___
a. How many errors the system will detect and correct
b. The overall function and needs of the networks
c. The efficiency of the code that results from the design
135. The main purpose of a data link content monitor is to___
a. Determine the type of switching used in a data line
b. Determine the type of transmission used in a data link
c. Detect problems in protocols
136. The total absorption area of a room of 2000 square meter surface area, if half of this surface has absorptivity of 0.1 and the other half is 0.3
a. 400 sq. mb. 800 sq.mc. 750 sq. md. 5000 sq .me. 13,333.33 sq. m
137. Architecturally, link protocols are at a level___
a. Lower than physical protocols
b. The same as physical protocols
c. Higher than physical protocols
138. Which of the following statements is false?
a. Cyclic Redundancy Checking can find all of certain kinds of errors, and more than 99.3% of most other kinds.
b. A Hamming Code of distance 5 can detect and correct 4 errors in transmission.
c. Parity checking is capable of providing enough information to detect and correct errors
d. Checksums detect errors more effectively than checking
139. The most sophisticated type of data communications test equipment is the ___.
a. Simulatorb. Protocol Analyzerc. DTEd. Breakout Boxe. Synthesesizer
140. What is the reverberant sound level of the 100 cubic meter room, reverberation time of 1.2 seconds and moderately vigorous speaking voice can produce acoustic power in the order of 100 microwatts?
a. 60 dBb. 58.8 dBc. 64.2 dBd. 75 dBe. 120 dB
141. A data packet is a packet header together with ____.
a. A network layerb. An administrative layerc. User datad. A packet switche. Either (a) or (b)
142. Pulse Duration Modulation is ___.
a. Similar to FMb. Difficult to detect
accuratelyc. Not widely usedd. Vulnerable to noisee. Similar to wave division
multiplexing
143. Full capability dialed up backup of a multipoint full- duplex 4800 bps private line having 4 remote drops requires ____.
a. 4 callsb. Either 4 or 8 callsc. 8 callsd. 16 callse. Can’t tell
144. What is the basic function of a Public Address System (PAS)?
a. Distortionless Sound Reproduction
b. Maximum Powerc. Intelligible Information
Transferd. Frequency Responsee. None of these
145. A network node joining three or more links is a ____.
a. DSEb. DTEc. DCEd. DTE and DCEe. None of these
146. Pulse Amplitude Duration Modulation is ___.
a. Similar to amplitude modulation in the analog world
b. Used in radio communications
c. Relatively insensitive to noise distortion
d. A version of frequency modulation
e. None of these147. The X.25 standard
specifies how many separate protocol layers at the serial interface gateway?
a. 8b. 2c. 4d. 3e. 6
148. What unit equalizes the time arrival for the sound reinforcement wavefront and the direct sound wavefront at the listening position?
a. High Powe Amplifierb. Hi- Fi amplifierc. Mixerd. Time Delaye. Reverb
149. Ducting in the atmosphere may cause microwave signals to ___.
a. Travel Longer Distancesb. Increase Signal Intensityc. Travel Shorter Distancesd. Improve C/N Ratioe. None of these
150. A 24 voice channel is sampled at 8,000 hertz and encoded into an 8- bit PCM word. The approximate rate of the data stream is ___.
a. 2.048 Mbpsb. 6.28 Mbpsc. 44.735 Mbpsd. 1.544 Mbpse. 2.056 Mbps
151. The (Link Access Procedure Balanced) LABP frame structure and the frame structure of SDLC are:
a. Oppositeb. Identicalc. Reversedd. Amorphouse. None of these
152. What is an early sound arriving from infront of the listener or from the ceiling overhead may leave a feeling of remoteness from the source?
a. Direct soundb. Reverberant soundc. Freedom from noised. Envelopmente. Flutter
153. At microwave frequencies, the LOS distance is sometimes extended through the occurrence of ___.
a. Ionospheric Reflectionsb. Fogc. Sporadic Ed. Dellinger Dropoutse. Ducting
154. The best system configuration to overcome multipath fading on “over-the water” propagation
a. Angle diversityb. Frequency diversityc. Non-diversityd. Space diversity
155. Establishing a virtual connection is functionally equivalent to:
a. Connecting a virtual memory
b. Experimental with virtual reality
c. Physically connecting a DTE and DCE
d. Placing a telephone call prior to a connection
156. How much acoustic power must a public address be able to put out in order to create SPL= 100dB for a musical show in a 105
m3 auditorium with reverberation time of 1.2 seconds?
a. 28.6 watts
b. 33 wattsc. 31.4 wattsd. 29.8 wattse. 300 watts
157. The quality of digital transmission is measured in terms of
a. Beamwidthb. BERc. Distortiond. Modulation usede. Traffic density
158. In a radio system, noise was measured at 58dBrn. What is its value in dBm?
a. 32b. -32c. 90d. 98e. 148
159. In X.25 network layer protocol, the data packets normally contain:
a. One octet of header plus data
b. Two octets of header plus data
c. Three octets of header plus data
d. Four octets of header plus data
160. Spectrum of a changing source which is continually updated during the change with no incoming data ignored
a. Digital analysisb. Heterodyne analyzerc. Tunable filterd. Real-time analysise. Tunable filter
161. The standing wave ratio of a transmission line can be measured by a:
a. Bolometerb. Power meterc. Reflectometerd. Stroboscopee. Voltmeter
162. In measuring noise, a circuit indicated 58dBrnc with tone and a 33dBrnc in C-notch reading. The S/N ratio of the circuit is__
a. 19 dBb. 25 dBc. 33 dBd. 52 dBe. 91 dB
163. The OSI reference model isa. A protocolb. Not a protocolc. A polling sequenced. Sequence
164. The reference level for sound in air
a. 6 x 10-6 pa2/Hzb. 4 x 10-3 pa2/Hzc. 4 x 10-10 pa2/Hzd. 6 x 10-4 pa2/Hz
165. One method of producing a broadband tuned circuit is by way of
a. Critical couplingb. Loose couplingc. Overcouplingd. Undercoupling
166. An transmitter is rated 100 watts at 100% modulation. The power required for the carrier is__
a. 33.33 wattsb. 50 wattsc. 66.67 wattsd. 86.67 wattse. 100 watts
167. Layer 1 of the OSI model isa. Link layerb. Network layerc. Physical layerd. Session layer
168. The pressure spectrum level at 2 kHz
a. 25.78dBb. 33.47 dBc. 45.32 dBd. 62.51dBe. 120 dB
169. Color TV is made possible through the combination of the primary colors of
a. blue, yellow, greenb. red, green, bluec. red, white , blued. white, red, green
170. A type of modulation technique that conveys audio information from one station to another by varying the carrier frequency at the audio rate
a. Amplitude modulationb. Frequency modulationc. Quadrature modulationd. Phase modulation
171. The applications layer of the OSI model is the
a. First layerb. Second layerc. Seventh layerd. Sixth layere. Third layer
172. Causes modulation either in its internal circuitry or in another associated circuit
a. Detectorb. Modulatorc. Multivibratord. Multiplexer
e. Phasor173. The half-power points of
the beamwidth of the front lobe of a directional antenna is the point equal to
a. 0.707b. 0.636c. 0.318d. 0.5e. 1.414
174. A tuned amplifier uses___load
a. Capacitiveb. Inductivec. LC tankd. Resistive
175. When a single antenna is intended to be used for transmitting and receiving , it is necessary to use__
a. Combinerb. Diplexerc. Duplexerd. Multiplexere. Transponder
176. The receiver’s ability to receive both very weak and extremely strong stations without introducing distortion
a. Dynamic rangeb. Effective rangec. Figure of meritd. Sensitivitye. Selectivity
177. The T-1 North American digital system has 24 channels and require a transmission speed of
a. 64 kbpsb. 640 kbpsc. 960 kbpsd. 1.54 Mbpse. 2.048 Mbps
178. A tuned amplifier is used in ___ applications
a. Audio frequencyb. Low frequencyc. Optical frequencyd. Radio frequency
179. The higher the Q of a circuit, the __ is the frequency bandwidth
a. Broaderb. Low selectivec. Higher stabilityd. Narrower
180. Considered as an FM demodulators
a. Foster-Seely Discriminator
b. Phase-locked loopc. Radio detectord. All of thesee. None of these
181. What is the image frequency when the receiver is tuned to9.81 MHz, the local oscillator is tuned above the desired signal, and the intermediate frequency is 455 kHz?
a. 8.355 MHzb. 8.9 MHzc. 10.265 kHzd. 10. 720 MHze. 11.72 MHz
182. One of the main functions of the RF amplifier in a superheterodyne receiver is to__
a. Improve the rejection of the image frequency
b. Increase tuning range of the receiver
c. Permit better adjacent-channel rejection
d. Provide improve tracking183. At resonance, the circuit
power factor is__a. 0b. 1c. 0.5d. 0.8e. Infinity
184. In broadcast superheterodyne receiver, the__
a. Local oscillator operates below the signal frequency
b. Mixer input must be tuned to the signal frequency
c. Local oscillator frequency is normally double the IF
d. RF amplifier normally works at 455 kHz above the carrier frequency
185. The voltage gain of a tuned amplifier is __ at resonant frequency
a. Halfway between minimum and maximum
b. Maximumc. Minimumd. zero
186. In an FM stereo multiplex transmission, the __
a. Difference signal modulates the 38 KHz subcarrier
b. Difference signal modulates the 67 KHz subcarrier
c. Difference signal modulates the 19 KHz subcarrier
d. Sum signal modulates the 19 KHz subcarrier
187. At parallel resonance, the line current is__
a. Maximumb. Minimumc. Between maximum and
minimumd. Zero
188. In amplitude modulation, bandwidth is ___ the audio signal frequency
a. Thriceb. Four timesc. Twiced. Five timese. Six times
189. At series resonance, the circuit offers __ impedance
a. Infinityb. Negativec. Maximumd. Minimume. Zero
190. It a system which provides the longest digital transmission distances
a. Computer busb. Digital PBXc. Local area networkd. Voice band modem
191. When modulating frequency is disabled , the modulation index is halved, and the modulating voltage remains constant. The modulating system is __
a. Amplitude modulationb. Frequency modulationc. Phase modulationd. Pulse modulation
192. Which of the functions is not provided as part of the basic Ethernet design?
a. Access controlb. Addressingc. Automatic
retransmissiond. Multiple virtual networks
193. The frequency the oscillator must be set at for an output of 95 kHz if the output of the oscillator is being fed to two frequency triplers connected in cascaded form
a. 6.3 MHzb. 9.65 MHzc. 10.56 MHzd. 15.8 MHz
194. A resonant circuit contains ___ element
a. R and Lb. Only Rc. R and Cd. L and C
195. For a monoaural FM receiver, it only receives the__
signal of a stereo multiplex transmission
a. L-Rb. L+Rc. R-Ld. 2R + Le. R + 2L
196. At resonance, a circuit behaves as a ___ load
a. Capacitiveb. Inductivec. magneticd. PN junctione. Resistive
197. The purpose of the preamble in an Ethernet is__
a. Broadcastb. Clock synchronizationc. Error checkingd. Collision avoidance
198. Pre-emphasis and de-emphasis are used in the FM stereo multiplex system to improve__
a. Current ratiob. CMRRc. Power ratiod. Standing wave ratioe. Signal-to-noise ratio
199. At series resonance, the voltage across L is___ voltage across C
a. Equal to but in phase withb. Equal to out of phase
withc. Greater than but in phase
withd. Less than but in phase
with200. The frequency tolerance
for the RF carrier in the standard AM radio broadcast band is___
a. Zerob. ± 20 Hzc. ± 25 Hzd. ± 75 Hze. ± 1000 Hz
201. The TV visual carrier uses a ____transmission
a. Lincompexb. Pilot carrier systemc. SSBSCd. Vestigial sideband
202. When either L or C is increased, the resonant frequency of LC circuit___
a. Decreasesb. Increasesc. Remains the samed. None of these
203. Phosphor colors for a tricolor picture tube
a. Red, yellow, greenb. Blue, red, yellow
c. Red, blue , magentad. Red, green , bluee. Red, white, blue
204. At parallel resonance____a. IL < IC
b. IL = IC
c. Ic > IL
d. IL>> IC
e. IL << IC
205. In parallel LC circuit, if the input signal is increased above resonant frequency, then___
a. XL decreases XC increasesb. XL increases XC decreasesc. Both XL and XC increased. Both XL and XC decrease
206. In amplitude modulation___ of carrier is varied according to the strength of the signal.
a. Amplitudeb. Frequencyc. Phased. period
207. The Q of an LC circuit is given by__
a. XL/Rb. R/XL
c. XL x Rd. R2/XL
e. LC/R208. In AM wave, the majority
of the power is in____.a. Equal tob. Less thanc. Greater than
209. The exact vertical field scanning frequency for color TV
a. 3.579545MHz b. 59.94Hzc. 15,734.27Hzd. 3.58 MHz
210. Any deviation in frequency of reproduced sound from the original frequency
a. Consonanceb. Flutterc. Reverberationd. Rumblee. Wow
211. If Q of an LC circuit increases, the bandwidth
a. Is decreasedb. Is increasedc. Remains the same
212. If L/C ratio of a parallel LC circuit is increase, the Q of the circuit ____.
a. Is increasedb. Is decreasedc. Remains the samed. Either (a) or (b)
213. The transmit frequency range of a cellular telephone system is ____.
a. 140-50 MHzb. 138-174 MHzc. 156-165 MHzd. 825-845 MHz
214. At resonance, the phase angle between applied voltage and circuit current is ____.
a. 90°b. 180°c. 0°d. 270°
215. The channel spacing in a cellular telephone is ____.
a. 1 HKzb. 30 KHzc. 1 MHzd. 150 Hze. 25 Hz
216. If the resistance of a tuned circuit is increase, the Q of the circuit _____.
a. Remains the sameb. Is decreasedc. Is increasedd. Either (a) or (c)
217. The separation between transmit and receive signals in cellular phones is____.
a. 15b. 25c. 35d. 45e. 55
218. A parallel LC circuit draws a line current of 1 mA at resonance. If Q of the circuit is 100, then each branch current is ____.
a. 0.01 mAb. 100 mAc. 0.5 mAd. 50 mAe. 300 mA
219. The Automatic Power Control Circuit of a cellular phone causes the transmitter power to ____ based on an input control signal from the MTSO.
a. Change or decreaseb. Remain constantc. Reverberated. Bounce back and forth
220. The resonant frequency of an LC circuit is 1 Megahertz. If L is doubled but C is reduced to one eighth of the original value, the resonant frequency will be ____.
a. 500 KiloHertzb. 250 KiloHertzc. 1 MegaHertzd. 2 MegaHertz
221. A DC signal derived from the demodulator and used to tell the MTSO about received signal strength is called _____.
a. VU meterb. SWR Indicatorc. Received Signal Strength
Indicatord. Dosimeter
222. The Q of a tuned circuit refers to the property of ____.
a. Selectivityb. Sensitivityc. Fidelityd. Conductivity
223. The third harmonic of 400 Hertz is___
a. 300 Hzb. 400 Hzc. 800 Hzd. 1200 Hze. 1600 Hz
224. A coil has XL = 1000 ohms and 5 ohms internal resistance. Its Q is equals to ___.
a. 0.005b. 200c. 1000d. 2000e. 5000
225. The section of the cellular transceiver that interprets the serial digital data from the cell site and the MTSO is the ____ unit
a. Arithmeticb. Bufferc. CPUd. Finale. Logic
226. In a parallel LC circuit, if the signal frequency is decreased below resonant frequency , then ___
a. XL decreases and XC
increasesb. XL increases and XC
increasesc. XL and XC both decrease
current is minimumd. Line current is minimum
227. How many microprocessors do most cellular transceivers contain?
a. 1b. 2c. 3d. 4e. 5
228. The sharpness of a resonance curve depends upon ___ of the tuned circuit
a. Fidelityb. Friction of electronsc. Particle dispersion
d. Qe. Sensitivity
229. When the speed of a radio signal is known, radar can be used to determine ___ of a target
a. Altitudeb. Blind speedc. Directiond. Doppler shifte. Range
230. For frequencies above the resonant frequency, parallel LC circuit behaves as a _____ load
a. Capacitiveb. Inductivec. Resistived. Reverse biased
231. In cellular telephones, the receive frequency range is between ___ Megahertz
a. 138-174b. 140-150c. 500-600d. 800-900e. 825-845
232. The directivity of RADAR antenna determines the ____ of a target
a. Azimuthb. Angle of elevationc. bearingd. either a or ce. Either a or b
233. Printed documents to be transmitted by fax are converted into a baseband electrical signal by the process called___
a. Light variationb. Modulationc. Photostatd. Scanninge. Reflection
234. The elapsed time between a radiating radar signal and receiving its echo is 43.2 microseconds. The target distance is___ nautical miles
a. 3.5b. 4.5c. 5.5d. 6.5e. 7.5
235. The most commonly used light sensor in a modern fax machine is a ___
a. Charge coupled deviceb. Liquid crystal displayc. LASCRd. Phototransistore. Phototube
236. A waveguide assembly that lets the radar transmitter and receiver share an antenna is called___
a. Diplexerb. Duplexerc. Flip-flopd. Translatore. Toggle switch
237. Resolution which produces the best quality fax
a. 96 lines/inchb. 150 lines/inchc. 200 lines/inchd. 300 lines/inche. 400 lines/inch
238. Most commonly used component in a RADAR transmitter is a/an__ tube
a. Cyclotronb. Dynatronc. Magnetrond. Twystrone. Voltron
239. Group of two (2) fax machines uses ____ modulation
a. SSBb. FSKc. Independent Sidebandd. PSKe. Vestigal Sideband
240. A radar using multiple antennas to shape the beamwidth and automatically adjust directivity is known as _____.
a. Phased Arrayb. Continuous Wavec. Pulserd. Search and Rescue
241. In television systems, the spacing between sound and picture carrier is _______ Megahertz
a. 6b. 4.5c. 63.6d. 525
242. Most fax machines are of which type?
a. Impactb. Thermalc. Electrosensitived. Laser Xerographic
243. The transmission speed of Group four (4) fax machine is ____.
a. 4800 Baudsb. 9600 Baudsc. 56 Kbpsd. 192 kbps
244. A popular half-wavelength antenna is the ____________.
a. Ground-planeb. End-firec. Collineard. Dipole
245. The maximum frequency deviation of a cellular transmitter is ______.
a. 6 KHzb. 12 KHzc. 30 KHzd. 45 KHZ
246. Popular vertical antenna is the
a. Collinearb. Dipolec. Ground-planed. Broadside
247. The master control center for a cellular telephone system is the ______.
a. Cell siteb. Mobile Telephone
Switching Officec. Central Officed. Branch Office
248. The magnetic field of an antenna is perpendicular to the earth. The antenna’s polarization in
a. Verticalb. Horizontalc. Circulard. Elliptic
249. Each cell site contains a _____.
a. Repeaterb. Control computerc. Direct link to a PABXd. Touch-tone processor
250. Cellular telephones operate in _____ mode, whereas trunking radios operate _______mode, respectively.
a. Simplex, simplexb. Full-duplex, half-duplexc. Triplex, full-duplexd. Half-duplex, simplex
251. An antenna that transmits or receives equally well in all directions or receives equally well in all directions is said to be _______.
a. Omnidirectionalb. Birectionalc. Unidirectionald. Quasidirectional
252. The output power of a cellular radio is controlled by ___________.
a. User or Callerb. Cell sitec. Called partyd. MTSO
253. Treble tome corresponds to _____.
a. High frequenciesb. Low frequencyc. High amplitudes
d. Low amplitudes254. When a signal from a
mobile cellular unit drops below a certain level, what action occurs?
a. The unit is “handed-off” to a closer cell
b. The cellphone searches for lost signal
c. The cell site switches antennas
d. The cell is terminated255. Typical loudspeaker
impedance rating is _________.a. 1 Ohmb. 8 Ohmsc. 100 Ohmsd. 5000 Ohms
256. Time from the transmission of a radar pulse to its reception is 0.12 msec. The distance to the target is _________ nautical miles.
a. 4.85b. 11.2c. 18.4d. 9.7
257. Typical output from a magnetic microphone is _________
a. 1 mVb. 500 mVc. 1 voltd. 2 volts
258. The ability of the radar to determine the bearing to a target depends upon the _________________.
a. Antenna Directivityb. Speed of lightc. Speed or targetd. Effective capture area
259. At series resonance, the voltage across L or C is ______ the applied voltage
a. Equal tob. Less thanc. Much mored. Either a or b
260. The 45° - 45° system refers to stereo for ________.
a. Magnetic tape recordersb. Photograph recordsc. Crystal microphonesd. Loudspeakers
261. For frequencies below the resonant frequency, a parallel LC circuit behaves as a _________ load
a. Resistiveb. Capacitivec. Inductived. Either a or b
262. The tape speed for cassette tape recorders, I inches per second is
a. 1 7/8b. 3 ¾
c. 45d. 15
263. In series resonance, there is ______.
a. Voltage amplificationb. Current amplificationc. Both voltage and current
amplificationsd. Power attenuation
264. Which of the following would apply to the audio power output stage?
a. Low-level signalb. Complementary
symmetryc. Class cooperationd. Very little distortion
265. In parallel resonance, there is __________.
a. Current Amplificationb. Voltage Amplificationc. Both a and bd. Power Attenuation
266. To Match 8 Ohms to 200 Ohms, an audio output transformer must have turns ratio of
a. 1:1b. 1:5c. 1:8d. 1:400
267. In a parallel LC circuit, each branch current carries a current of 1 at resonance. If the Q of the circuit is 100, then line circuit is _________.
a. 100 x Ib. 200/Ic. 100/Id. I/100
268. Negative feedback is used in audio amplifiers to
a. Increase gainb. Increase distortionc. Reduce distortiond. Operate class c
269. For frequencies below resonant frequency, a series LC circuit behaves as a _____________ load
a. Resistiveb. Capacitivec. Inductived. Either a and b
270. Less capacitive reactance in shunt with audio amplifier has the effect of
a. Bass cutb. Treble boostc. Treble cutd. More negative feedback
271. For frequencies above resonant frequency, a series of LC circuit behaves as a _______ load.
a. Inductiveb. Capacitivec. Resistived. Purgative
272. The auxiliary input jacks of a ratio receiver require audio output of _________.
a. 0.1 to 0.5 mVb. 1 to 5 mVc. 200 to 500 mVd. 5 to 10 volts
273. Tuning is generally accomplished by charging ________ of the tuning circuit
a. Both L and Cb. Lc. Cd. RL
274. Two 4 Ohm speakers in series have a total impedance of
a. 2 Ohmsb. 4 Ohmsc. 8 Ohmsd. 16 Ohms
275. If a high degree of selectivity is desired, then tuned circuits should have _______ coupling
a. Looseb. Tightc. Criticald. Both b and c
276. The gain of an RF amplifier with a tuned LC circuit for the collector is maximum at resonance at the resonant frequency because of ___.
a. Series resonanceb. Parallel resonancec. Low Qd. High Emitter Resistance
277. If the coupling between tuned circuits is increased, the level of resonance curve _______
a. Remains the sameb. Is raisedc. Is loweredd. Either a or c
278. The Q of a single tuned circuit is lower when its
a. Series R, is reducedb. Shunt RD is reducedc. Shunt RD is increasedd. Capacitance is reduced
279. Double tuned circuits are used in ____________ stages of a radio receiver
a. IFb. Outputc. Audiod. RF
280. The pulse duration of a RADAR signal is 600 nanoseconds.
The PRF is 185 pulses per second. The duty cycle is ______.
a. 0.01%b. 5.5%c. 31%d. 47%
281. Snow in a TV picture is a result of ______.
a. High Q in the tuned circuits
b. Excessive gainc. Random noise in the
signald. Insufficient wavetraps
282. Doppler effect allows which characteristic of a RADAR target to be measured?
a. Distanceb. Speedc. Size of Targetd. Azimuth
283. The response curve of a double-tuned circuit shows two peaks when the transformer has ___________.
a. Loose couplingb. Critical couplingc. Tight couplingd. Excessive dampling
284. The Doppler effect is a change in what signal characteristic produced by relative motion between RADAR set and a target?
a. Amplitudeb. Phasec. Frequencyd. Duty cycle
285. Which of the following methods can not be used to increase the bandwidth for cascaded RF amplifier stage?
a. A shunt damping resistor across each tuned circuit
b. Stagger tuningc. Wave traps in each staged. Double-tuned
transformers with tighter coupling
286. The most widely used oscillator in a radar transmitter is
a. Klystronb. Magnetronc. TWTd. Power Transistor
287. Which of the following circuits has the greatest bandwidth?
a. fr is 50 MHz with Q of 50b. fr is 455 KHz with Q of
100c. fr is 1 MHz with Q of 100d. fr is 1 MHz with Q of 10
288. Low power radar transmitters and receiver local oscillator use
a. Ga As FETb. Twystronc. Gunn Dioded. Varactor
289. When both primary and secondary resonant circuits of a double-tuned transformer have a Q of 50, the value of critical coupling Kc is _____.
a. 50b. 0.5c. 1d. 1/50 or 0.2
290. Most radar antennas use a _____.
a. Dipoleb. Broadside arrayc. Horn and parabolic
reflectord. Collinear array
291. Two main parts of a tank circuit are _______.
a. R and Cb. R and Lc. R and an NPN Transistord. L and C
292. The most common radar display is ______.
a. A-scopeb. Color CRTc. Liquid Crystal Displayd. Plan Position Indicator
293. When L is doubled and C is halved, the resonant frequency (fr) is
a. Doubleb. One-halfc. One quarterd. The same
294. A radar antenna using multiple dipoles or slot antennas in a matrix with variable phase shifters is called ________.
a. A-scanb. Phased Arrayc. Broadside arrayd. Endfire array
295. Positive feedback is the same as _____.
a. Regenerationb. Degenerationc. Negative feedbackd. Frequency synthesis
296. The black and white or monochrome brightness signal in TV is called _________.
a. RGBb. Color subcarrierc. Q and Id. Luminance Y
297. The oscillator that uses a tapped coil in the LC tuned circuit is the __________.
a. Pierceb. Colpittsc. Hartleyd. Wien
298. The assembly around the neck of the TV picture tube that produces the magnetic fields to deflect and scan the electron beam is called _______.
a. Shadow maskb. Phosphorc. Electron gund. Yoke
299. The circuit that uses a capacitive voltage divider to provide feedback is the _____________.
a. Colpittsb. Hartleyc. Armstrongd. Multivibrator
300. What type of circuit is used to modulate and demodulate the color signals of television?
a. Phase Locked Loopb. Differential Peak Detectorc. Quadrature Detectord. Balanced Demodulator
301. RF feedback oscillator are usually tuned by varying the _____.
a. Biasb. Supply Voltagec. L or Cd. Load Impedance
302. What TV receiver circuit is used to develop the high voltage needed to operate the picture tube?
a. Low voltage power supplyb. Horizontal Outputc. Vertical sweepd. Sync separator
303. The oscillator with the best frequency stability and accuracy is the
a. Hartleyb. Colpittsc. Ticker feedbackd. Crystal controlled
304. The technique used to allow hundreds of TV signals to share a common cable is ________
a. Frequency Modulationb. Mixingc. Time division multiplexingd. Frequency division
multiplexing305. When a 5 MHz crystal is
followed by a frequency tripler, the output will be _____.
a. 6 MHz
b. 12 MHzc. 18 MHzd. 54 MHz
306. The varactor in a Voltage Controlled Oscillator (VC0) needs ____.
a. Audio signal below 1000Hz
b. Reverse DC control voltage
c. Forward biasd. Parallel capacitance more
than 5 microfarads307. The phase comparator in a
PLL circuit is used to provide a. One-half of the crystal
oscillator frequencyb. RF output with audio
modulationc. DC Control voltaged. Double the crystal
oscillator signal308. In which of the following
frequency bands are the standard AM broadcast stations?
a. MFb. HFc. VHFd. UHF
309. The commercial FM radio broadcast band is
a. 535 to 1605 KHzb. 27 to 29 KHzc. 88 to 108 MHzd. 300 to 3000 MHz
1. The RF power output of a transmitter in a cellular mobile telephone system authorized by NTC for use in the Philippines.a. 20.5 dBm c 31.5 dBm b. 34.8 dBm d. 22.1 dBm
2. In telephony, M88 loading coil (88-mH loading coil) is placed at an interval of ______ feet.a. 5000 c. 7500 b. 8000 d. 9000
3. MPEG 21 is the standard that aims at defining an open framework for MULTIMEDIA applications with standard namea. ISO/IEC 14496 c.
ISO/IEC 2100 b. ISO/IEC 15938 d.
ISO/IEC-13818
4. In digital television, 480 p format means _____
a. 480 x 640 pixels interlace b. 480 x 640 pixels progressivec. 640 x 480 pixels interlace d. 640 x 480 pixels progressive
5. The average absorption of a person is
a. 1.7 sabines b. 4.7 sabines c. 47 sabinesd. 7.4 sabines
6. For TV broadcasting stations, median field strengths required for various grades of service are oftentimes expressed in dBu. It signifies the field strength in decibels above______a. one microvolt per ft b. one microvolt per km c. one microvolt per meterd. one millivolt per meter
7. OSI network layer which has aninter-host communicationa. network layer b. physical layerc. presentation layer d. session layer
8. The IEEE 802.4 standarda. Token passing for bus
topologyb. Token passing for ring
topologyc. Token passing for mesh
topologyd. Token passing for star
topology
9. Code assigned to duly authorized local access network providers for 3G Network Operators.a. 100 c. 209b. 306 d. 404
10. Among the connectors and transmission lines for coaxial, which is the least expensive as is widely used for CATV, VCRs, and TV sets?a. F – type c. PL – 529 b. L-type d. RG -11
11. A section which would be a complete antenna by itselfa. bay c. gayb. hay d. hertz
12. In accordance with the Philippine Electronics Code, the maximum radiation from electronics equipment must not exceed ____ per week in order not to experience genetic and somatic damage to cells.
a. 1 rem c. 100 rems b. 10 rems d. 50 rems
13. Determine BW efficiency for QPSK modulation at rate 10 Mbps.
a. 1 bit/cycle c. 3 bits/cycle
b. 2 bits/cycle d. 4 bits/cycle
14. To make the tape speed the same in playback as in recording, the tape speed is regulated by the
a. audio track b. control-track pulses c. erase headd. video slant tracks
15. Luminance signal or Y signal componentsa. 21 % red, 52 % green & 31 %
blue b. 30 % red, 59 % green, & 11 %
bluec. 60 % red, 28 % green, & 32 %
blue d. 30 % red, 11 % green, & 59 %
blue
16. Iridium is an example of LEO, and has a mean elevation ofa. 48 miles b. 84 miles b. 840 miles d. 480 miles
17. NTC has defined Outdoor Radio Equipment Devices used for Wireless Data Network as those effective power exceeds _____a. 150 mW b. 175 mW c. 200 mWd. 250 mW
18. The period for a single time slot in a GSM-TDMA slot structure is ____ μseca. 577 b. 57.7 c. 75.7 d. 757
19. The formula used to calculate the overall noise performance of a receiver or of multiple stages of RF amplification is the _____ formula
a. Arceo’s c. .Frii’s b. Hartley’s d.
Shannon’s
20. Mandatory date of compliance to NTC requirement of installing NAVTEX receiver by cargo and passenger vessels/ships engaged in coastwise trade is on or before ______
a. 30 September 2002 b. 30 September 2003 c. 30 Sept 2004 d. 30 Sept 2005
21. High speed networks as defined by the National Telecommunications Commission(NTC) memorandum circular are networks in ICT that
have a capacity of at least _______a. 1.024 Mbps c. 2.048
Mbpsb. 512 kbps d. 4.096
Mbps
22. The instrument used to measure the interval height of a layer in the ionosphere used for wave propagationa. Altimeter c. iconoscope b. ionosonde d. ionoscope
23. Horizontal polarization is nothing but
a. Circular polarizationb. Elliptical polarizationc. X-polarizationd. Y-polarization
24. The maximum electronic efficiency of reflex klystron
a. 40% c. 22.7%b. 50% d. 35%
25. Directional couplera. Amplifierb. Non-reciprocal devicec. Oscillatord. Reciprocal device
26. The maximum unambiguous range in a system depends on:
a. Maximum power of the transmitter
b. Pulse repetition frequencyc. Width of the transmitted
pulsed. Sensitivity of the radar
receiver
27. To calculate the Thevenin’s equivalent value in a circuit
a. All independent voltage sources are opened and all independent current sources are short circuited
b. All voltage and current sources are shorted
c. All voltage sources are shorted while current sources are opened
d. Both voltage and current sources are open circuited
28. The characteristic impedance of a low pass filter in attenuation band is
a. Complex quantityb. Purely imaginaryc. Real valued. Zero
29. The real part of the propagation constant shows:
a. Reduction in voltage, current values of signal
amplitudeb. Reduction of only voltage
amplitudec. Variation of phase
shift/position of voltaged. Variation of voltage and
current on basic unit
30. The control system of electronic switching systems are called as
a. Combination Switching System
b. Crossbar Systemsc. Gigantic Switching Systemd. Stored Program Control
Systems
31. A fully connected network supports full duplex communication using unidirectional links. The total number of links in such a network with n nodes is
a. nC2 c. 2 x nC2
b. n2 d. 2n
32. Near-end crosstalk refers to:a. Coupling form a transmitter
into a receiver at a common location
b. Interference caused by other cables routed close to the cable of interest
c. Unwanted coupling into a received from transmitter at a distant location
d. None of these
33. The horizontal resolution of a picture is decided by:
a. Aspect ratiob. No. of horizontal linesc. No. of vertical linesd. Pixel
34. The chrominance signal isa. Result of colour difference
signalsb. Resultant of modulated
quadrature colour difference signals
c. Sum of colour difference signals
d. Sum of primary colours
35. The patter of scanning lines in a video system
a. Interfaceb. Rasterc. Resolutiond. Retrace
36. With an increase in temperature, the Fermi level in an intrinsic semiconductor
a. Moves closer to the conduction band edge
b. Moves closer to the valence band edge
c. Moves into the conduction band
d. Remains at the centre of forbidden gap
37. The purpose of impedance matching between the output of previous stage and input of next stage in a cascaded amplifier
a. To achieve high efficiencyb. To achieve reduced
distortionc. To achieve maximum
power transferd. To achieve reduced noise
38. If one of the diode in a full wave bridge rectifier opens the output is
a. 0 Vb. ¼ of the amplitude of the
input voltagec. A half wave rectified
voltaged. A 120 Hz voltage
39. The expression for carrying C in the half adder with inputs A and B is given by
a. ABb. A.Bc. ABd. None of these
40. Bandwidth of MSK is ___ that of QPSK
a. Equal tob. Higher thanc. Less than or equal tod. Lower than
41. Which of the following modulation schemes provides 4 bits per baud?
a. QPSKb. 16-QAMc. 8-PSKd. 64- AQAM
42. Hamming weight (Si) of a code Si is defined as the
a. No of 0’s in codeword Sib. No. of 1’s in codeword Sic. No. of 1’s in even locations
of Sid. No. of 0’s in even locations
of Si
43. In the eye pattern, as eye closesa. ISI decreasesb. ISI increasesc. Timing jitter decreasesd. Timing jitter increases
44. The CRC circuit is basicallya. Adder circuitb. Decoder circuitc. Multiplexer circuitd. Shift register circuit
45. When a thyristor gets turned on, the gate drive
a. May or may not be removedb. Should be removedc. Should be removed in order
to avoid increased losses and higher junction temperature
d. Should benot be removed as it will turn-off the SCR
46. The intersection of a V-I curve with the load line is called the
a. Load pointb. Q-pointc. Transfer curved. Transition point
47. If a single diode in a center tapped full-wave rectifier opens, the output
a. 0Vb. Half-wave rectifiedc. Reduced in amplituded. Unaffected
48. The purpose of a small capacitor placed across the output of an IC regulator is to
a. Couple the output signal to the load
b. Filter the acc. Improve transient responsed. Protect the IC regulator
49. When the collector resistor in a CE amplifier is increased in value , the voltage gain
a. Becomes erraticb. Decreasesc. Increasesd. Is not affected
50. The place where telephone companies terminate customer lines and locate switching equipment to interconnect those lines with other networks
a. Central officeb. Customer care centrec. Customer premises endd. Network service providers
51. ___ layers of OSI model send frames with the necessary synchronization, error control and flow control
a. Data linkb. Networkc. Physical d. Transport
52. In___ coding scheme, 0 is transmission from high to low in middle of interval and 1 is the transition from low to high in middle of interval
a. Bipolar AMIb. Differential Manchesterc. Manchesterd. Pseudoternary
53. The ISDN encodinga. 2B1Q encoding c. 4B2Q
encoding b. 1B2Q d. 2B2Q
54. Typical PBX configurationa. Star topology c. bus
topologyb. ring topology d. mesh
topology
55. 3G wireless technology that has a Broadband-like data speeda. WIFI c. EDGEb. WIMAX d. ZIGBEE
56. One of the following if NOT a system specification for 3G wireless system.a. IMT 2000 c.
TC/CDMAb. CDMA 2000 d. WCDMA
57. 3G wireless technology that has a Broadband-like data speedc. WIFI b. EDGE c. WIMAX
d. ZIGBEE
58. One of the following if NOT a system specification for 3G wireless system.c. IMT 2000 c.
TC/CDMA d. CDMA 2000 d.
WCDMA
59. Room whose boundaries absorbs effectively all incident sounda. acoustic roomb. anechoic roomc. Helmholtz resonator d. Helmholtz room
60. Navigational display that provides range versus azimuth.a. A-scope c. B-scanb. PPI d. RHI
61. An 802 standard used for wireless regional area network.a. 802.25 b. 802.16 c. 802.19
d. 802.22
62. In broadband ISDN (B-ISDN), the
channel rate of H21 is ______
a. 43 to 45 Mbps c. 132 Mbps
b. 138.24 Mbps d. 32.786 Mbps
63. Type of antenna array consisting of a linear arrangement of a simple dipoles fed 90˚ out of phase and have radiation pattern of maximum directivity in plane of the array.a. broadside arrayb. collinear arrayc. end-fire array d. parasitic array
64. In integrator, the feedback element is a
a. Capacitorb. Diodec. Inductord. Resistor
65. Wein-bridge oscillations are based on
a. High gainb. Negative feedbackc. Piezoelectric effectd. Positive feedback
66. A feature in which a data frame has a field to hold the sequence number of the frame as well as sequence number for acknowledgement
a. Flow controlb. Go-back-Nc. Piggy backingd. Stop and wait
67. The data rate provided by DS-I transmission format is
a. 2.048 Mbpsb. 64 kbpsc. 1.544 Mbpsd. 51.84 Mbps
68. Virtual Circuit Packet Switching needs
a. Dedicated pathb. Fixed bandwidthc. Non-dedicated pathd. None of the above
69. In ___ avoidance, the network alerts end systems to growing congestion they intrn reduce the offered load to the network
a. Implicit congestionb. Explicit congestionc. Both a and bd. None of the above
70. IEEE 802.ID specification defines the protocol architecture for__
a. LANSb. Bridgesc. Gateways
d. None of the above
71. In a transmission line terminated by characteristic impedance, Zo
a. The incident current is zero for any applied signal
b. The reflection is maximum due to termination
c. There are a large number of maximum and minimum on the line
d. There is no reflection of the incident wave
72. For a coil with inductance L and resistance R in series with a capacitor C has
a. Resonance impedance as infinity
b. Resonance impedance as zero
c. Resonance impedance L/RC
d. Resonance impedance R
73. All pass filtera. Passes all frequencies with
very low attenuationb. Passes all frequencies
without attenuation but phase is changed
c. Passes whole of the audio band
d. Passes whole of the radio band
74. A series resonant circuit is inductive at f = 1000Hz. The circuit will be capacitive somewhere at f 1000 Hz.
a. f 1000 Hzb. f 1000 Hzc. f equal to 1000 Hz and by
adding a resistance in seriesd. F = 1000 + fo ( resonance
frequency)
75. Compensation theorem is applicable to
a. Non-linear networkb. Linear and non-linear
networksc. Linear networksd. None of the above
76. In fast frequency hopping (FFH)a. Hopping rate is equal to or
greater than the bit rate of baseband signal
b. Hopping rate is equal to or less than the bit rate of baseband signal
c. The desired frequency and interference protection is less
d. None of the above
77. The use of non-uniformquantization levels lead to
a. Increase in maximum SNRb. Increase in SNR for low
level signalsc. Reduction in transmission
bandwidthd. Simplification of
quantization process
78. Which encoding method uses alternating positive and negative values for 1s?
a. NRZ-Ib. RZc. AMId. Manchester
79. CDMA technique is not used in satellite communication because of
a. Complexity of operationb. Increase in delayc. Wastage of bandwidthd. Wastage of power
80. In PCM system, the amplitude levels are transmitted in a 7 unit code. The sampling is done at rateof 10 kHz. The bandwidth should be
a. 35 kHzb. 5 kHzc. 5 MHzd. 70 kHz
81. The horizontal deflection circuit helps in the following processes
a. Horizontal and vertical deflection
b. Horizontal deflectionc. Horizontal deflection and
H,V generationd. Synchronization
82. In a TV receiver, the colour killera. Cuts off the chroma stages
during monochrome reception
b. Ensures that no colour is transmitted to monochrome receivers
c. Makes sure that the colour burst is not mistaken for sync pulses by cutting off reception during the back porch
d. Prevents overloading
83. CSMA stands fora. Carrier sense multiple
accessb. Central station mobile
applicationsc. Chart security maintenance
applicationd. Common signaling multi-
tone access
84. Materials which can store electrical energy are called
a. Magnetic materialsb. Semi-conductorc. Dielectric materialsd. Super conductor
85. A FET hasa. Current controlled featuresb. Forward biased p=n
junctionc. Very high input resistanced. Very low input resistance
86. A PN junction offereda. Conducts in forwarded
direction onlyb. Conducts in reverse
direction onlyc. High resistance in
forwarded as well as reverse direction
d. Low resistance in forwarded as well as reverse direction
87. Wireless access network unit (WANU) consists of:
a. Base station transceiversb. Access managerc. Radio controllerd. All of the above
88. The design process of selecting and allocating channel groups for all cellular base station within a system is called:
a. Adjacent channel interference
b. Co-channel interferencec. Frequency planningd. Near far affect
89. If the subscriber moves from one cell to other cell within BSC then this type of hand off is called:
a. Inter MSC handoverb. Inter-cell-inter BSC
handoverc. Inter-cell-intra BSC
handoverd. Intra-cell-intra BSC
handover
90. The expression Pe = Q (2Eb/No)1/2
is probability of error for which of the following:
a. QPSKb. BPSKc. DPSKd. /4 QPSK
91. If the bandwidth of signal is greater than that of channel then it is:
a. Fast fading
b. Frequency selective fadingc. Multipath fadingd. Slow fading
92. The major problem in a unipolar format of coding
a. Aliasingb. Complexityc. DC componentd. Synchronization
93. The detector that minimizes Pe if P(S1)= P(S2) is known as
a. Ratio detectorb. Minimum likelihood
detectorc. Discriminatord. Maximum likelihood
detector
94. Shannon’s Hartley Law isa. C = B log (1 +S/N) bits/secb. B = C log ( 1 + S/N) bits/secc. C= B log ( (1+S)/N) bits/secd. C = B log (1/N +S) bits/sec
95. Which protocol working at the Transport layer provides a connectionless service between hosts?
a. IPb. ARPc. TCPd. UDP
96. In OSI network architecture , the dialogue control and token management are responsibility of
a. Data link layerb. Network layerc. Session layerd. Transport layer
97. A routera. Determines on which
outgoing link a packet is to be forwarded
b. Forwards a packet to all outgoing links
c. Forwards a packet to the next free outgoing link
d. Forwards a packet to all outgoing links except the link upon which the packet originated
98. In AM a message signal of 5 kHz is modulated by a carrier of 100 kHz, the bandwidth of the modulated signal is
a. 5 kHzb. 10 kHzc. 100 kHzd. 105 kHz
99. An FM signal with a deviation is
passed through a mixer, and it has frequency reduction fivefold. The deviation at the output of the mixer is
a. b. 5c. /5d. 25
100.If the transmission line is properly matched, then the VSWR is
a. Ob. 1c. Less than 1d. Greater than 1
1. The discrete-time signal x (n) = (-1)n is periodic with fundamental period(A) 6 (B) 4(C) 2 (D) 0
2. The frequency of a continuous time signal x (t) changes on transformationfrom x (t) to x (α t), α > 0 by a factor(A) α . (B) 1/α(C) α2. (D) √α.
3. A useful property of the unit impulse (t) is that(A) (at) = a (t) . (B) (at) = (t) .(C) (at)=
(D) (at) = [ (t)]a.
4. Two sequences x1 (n) and x2 (n) are related by x2 (n) = x1 (- n). In the z- domain, theirROC’s are(A) the same. (B) reciprocal of each other.(C) negative of each other. (D) complements of each other.
5. The Fourier transform of the exponential signal ejw
0t is
(A) a constant. (B) a rectangular gate.(C) an impulse.(D) a series of impulses.
6. If the Laplace transform of f (t ) is ( ), then the value of
(A) cannot be determined. (B) is zero.
(C) is unity. (D) is infinity.
7. The unit impulse response of a linear time invariant system is the unit stepfunction u(t ). For t > 0, the response of the system to an excitation e-at u(t), a > 0, will be(A) ae-at
(B)
(C) a(1 - e-at) (D) (1 - e-at)
8. The auto-correlation function of a rectangular pulse of duration T is
(A)a rectangular pulse of duration T.(B) a rectangular pulse of duration
2T.(C) a triangular pulse of duration T.(D)a triangular pulse of duration
2T.
9. The FT of a rectangular pulse existing between t = -T / 2 to t = T / 2 is a
(A)sinc squared function. (B) sinc function.(C) sine squared function.(D) sine function.
10. An analog signal has the spectrum shown in Fig. The minimum samplingrate needed to completely represent this signal is(A) 3 KHz .(B) 2 KHz .(C) 1 KHz .(D) 0.5 KHz .
11. A given system is characterized by the differential equation:
The system is:(A) linear and unstable.(B) linear and stable.(C) nonlinear and unstable. (D) nonlinear and stable.
12. The system characterized by the equation y(t ) = ax(t )+ b is(A) linear for any value of b.
(B) linear if b > 0.(C) linear if b < 0. (D) non-linear.
13. Inverse Fourier transform of u(w) is
(A)
(B)
(C)
(D)
14. The impulse response of a system is h(n) = an u(n). The condition for the system to be BIBO stable is(A) a is real and positive. (B) a is real and negative(C) a > 1. (D) a < 1.
15. If R1is the region of convergence of x (n) and R2 is the region of convergence ofy(n), then the region of convergence of x (n) convoluted y (n) is(A) R1+R2 . (B) R1 - R2 .(C) R1 R2 .(D) R1 R2 .
16. The continuous time system described by y(t) = x (t2) is
(A)causal, linear and time varying.(B) causal, non-linear and time
varying.(C) non causal, non-linear and time-
invariant.(D)non causal, linear and time-
invariant.
17. If G(f) represents the Fourier Transform of a signal g (t) which
is real and odd
symmetric in time, then G (f) is(A) complex.
(B) imaginary.(C) real.
(D) real and non-negative.
18. If white noise is input to an RC integrator the ACF at the output is proportional to
(A)
(B)
(C) (D)
19. x(n) = a|n|, |a|<1 is(A)an energy signal.(B) a power signal.(C) neither an energy nor a power
signal.(D)an energy as well as a power
signal.
20. The spectrum of x (n) extends from - 0 to + 0 , while that of h(n) extends from -2 0 to + 2 0. The spectrum of y(n) = extends from(A) -4 0 to + 4 0.(B) -3 0 to + 3 0.(C) -2 0 to + 2 0. (D) - 0 to + 0
21. The signals x1(t ) and x2 (t) are both bandlimited to (- 1, + 1) and (- 1, + 1) and respectively. The Nyquist sampling rate for the signal x1(t) x2 (t) will be(A) 2 1 if 1 > 2
(B) 2 2 if 1 < 2
(C) 2 1 + 2)(D) 1 + 2)/2
22. If a periodic function f(t) of period
T satisfies f(t) = -f(t + T/2), then in its Fourierseries expansion,
(A) the constant term will be zero.(B) there will be no cosine terms.(C) there will be no sine terms.(D) there will be no even harmonics.
23. A band pass signal extends from 1 KHz to 2 KHz. The minimum sampling frequency needed to retain all information in the sampled signal is(A) 1 KHz. (B) 2 KHz.(C) 3 KHz. (D) 4 KHz.
24. The region of convergence of the
z-transform of the signal 2n u(n) -3n u(-n – 1)(A) is |z| >1. (B) is |z| <1.(C) is 2 < |z| < 3 .(D) does not exist.
25. The number of possible regions of convergence of the function
is
(A) 1. (B) 2.(C) 3. (D) 4.
26. Given a unit step function u(t), its time-derivative is:(A) a unit impulse.(B) another step function.(C) a unit ramp function. (D) a sine function.
27. The impulse response of a system described by the differential equation
will be
(A) a constant. (B) an impulse function..(C) a sinusoid. (D) an exponentially decaying function.
28. The function is denoted by:
(A) sin c( u). (B) sin c(u).(C) signum. (D) none of these.
29. The order of a linear constant-coefficient differential equation representing a systemrefers to the number of(A) active devices. (B) elements including sources.(C) passive devices. (D) none of those.
30. z-transform converts convolution of time-signals to(A) addition. (B) subtraction.(C) multiplication. (D) division.
31. Region of convergence of a causal LTI system(A) is the entire s-plane. (B) is the right-half of s-plane.(C) is the left-half of s-plane. (D) does not exist.
32. The DFT of a signal x(n) of length N is X(k). When X(k) is given and x(n) is computed from it, the length of x(n)(A) is increased to infinity(B) remains N(C) becomes 2N – 1 (D) becomes N2
33. The Fourier transform of u(t) is
(A) (B)
(C) (D) none of these.
34. The system having input x(n) related to output y(n) as y(n) = log10 x(n) is:(A) nonlinear, causal, stable.(B) linear, noncausal, stable.(C) nonlinear, causal, not stable. (D) linear, noncausal, not stable.
35. To obtain x(4 – 2n) from the given signal x(n), the following precedence (or priority)rule is used for operations on the independent variable n:(A) Time scaling Time shifting
Reflection.(B) Reflection Time scaling
Time shifting.(C) Time scaling Reflection
Time shifting.(D)Time shifting Time scaling
Reflection.
36. The unit step-response of a system with impulse response h(n) = (n) – (n – 1) is:(A) (n – 1). (B) (n).(C) u(n – 1). (D) u(n).
37. Zero-order hold used in practical reconstruction of continuous-time signals is mathematically represented as a weighted-sum of rectangular pulses shifted by:(A) Any multiples of the sampling interval.(B) Integer multiples of the sampling interval.(C) One sampling interval.(D) 1 second intervals.
38. The region of convergence of the z-transform of the signal x(n) ={2, 1, 1, 2}is (A) all z, except z = 0 and z = (B) all z, except z = 0.(C) all z, except z = . (D) all z.
39. When two honest coins are simultaneously tossed, the probability of two heads on anygiven trial is:(A)1 (B) 3/4(C)1/2 (D) ¼
40. A continuous-time periodic signal x(t) , having a period T, is convolved withitself. The resulting signal is(A) not periodic
(B) periodic having a period T(C) periodic having a period 2T (D) periodic having a period T/2
41. If the Fourier series coefficients of a signal are periodic then the signal must be(A) continuous-time, periodic (B) discrete-time, periodic(C) continuous-time, non-periodic (D) discrete-time, non-periodic
42. The region of convergence of a causal finite duration discrete-time signal is(A) the entire z-plane except z = 0(B) the entire z-plane except z = (C) the entire z-plane(D)a strip in z-plane enclosing j -axis
43. The transfer function of a stable system is H(z) =
Its impulse response will be(A) (0.5)n u[n] + (2)n u[n](B) (0.5)n u[-n – 1] + (2)n u[n](C) (0.5)n u[n] − (2)n u[-n −1] (D) − (0.5)n u[-n −1] − (2)n u[-n −1]
44. The probability cumulative distribution function must be monotone and(A) increasing (B) decreasing(C) non-increasing (D) non-decreasing
45. Convolution is used to find:(A) The impulse response of an LTI System(B) Frequency response of a System(C) The time response of a LTI system(D)The phase response of a LTI system
46. The Fourier Transform of a rectangular pulse is(A) Another rectangular pulse (B) Triangular pulse(C) Sinc function (D) Impulse.
47. The property of Fourier Transform which states that the compression in timedomain is equivalent to expansion in the frequency domain is
(A) Duality. (B) Scaling.(C) Time Scaling. (D) Frequency Shifting.
48. What is the Nyquist Frequency for the signal x(t) =3cos 50 t +10 sin 300 t – cos100 t?(A) 50 Hz (B) 100 Hz(C) 200 Hz (D) 300 Hz
49. The step response of a LTI system when the impulse response h(n) is unit stepu(n) is(A) n+1 (B) n(C) n-1 (D) n2
50. The function which has its Fourier transform, Laplace transform, and Z transformunity is(A) Gausian (B) impulse(C) Sinc (D) pulse