MCQ in Communications by Alejamdro H. Ballado, Jr.

MULTIPLE CHOICE QUESTIONS IN COMMUNICATIONS

ALEJANDRO H. BALLADO, Jr.

ECE BOARD PROBLEMS APRIL 1999 – NOVEMBER 2002 1. (ECE Board Problem, November 2001) “Compulsory interconnection” a.) EO 59 b.) EO 546 c.) EO 109 d.) Act 3846 2. (ECE Board Problem, November 2002) A single measuring circuit having a resistor if 10 kΩ is connected in series with a 0.5 μF capacitor. What is affective bandwidth? a.) 50 kHz b.) 5 Hz c.) 50 Hz d.) 500 Hz 3. (ECE Board Problem, April 1999) An aircraft deviation measured by an ILS localizer. a.) Altitude b.) Ground Speed c.) Vertical d.) Horizontal 4. (ECE Board Problem, November 2001) In order to have a maximum power transfer, what must be the relation of the input circuit impedance? a.) Equal Impedance b.) Infinity c.) Zero d.) Less Than 5. (ECE Board Problem, November 2001) The ratio of the speed of the light in vacuum to the speed of the light in a material. a.) Index of Refraction b.) Dielectric Constant c.) Velocity Factor d.) Permittivity

6. (ECE Board Problem, November 2001) What is the radiation pattern of a half – wave dipole? a.) Doughnut Shape b.) Bi-Directional c.) Unidirectional d.) Omnidirectional

7. (ECE Board Problem, November 2001) It is produced when an object travels faster than the speed of sound. a.) Shock Wave b.) Ultrasound c.) Sonic Wave d.) Light Wave 8. (ECE Board Problem, November 2001) The time used for reference for determining the capacity of accepting calls for telephone system. a.) 12 MN b.) High Usage Hour c.) 12NN d.) Low Usage Hour 9. (ECE Board Problem, November 2001) The term used for deafness of higher frequencies due to old age. a.) Ear Deafness b.) Cortial Deafness c.) Tinnitus d.) Presbycusis 10. (ECE Board Problem, November 2002) Single side band emission is most frequently used in what frequency band? a.) LF b.) HF c.) MF d.) VLF 11. (ECE Board Problem, November 2001) A device that converts voice to data. a.) Vocoder b.) Covoder c.) Modern

d.) Repeater 12. (ECE Board Problem, November 2001) A microwave device which permits signal only in one direction. a.) RF Emitter b.) Capacitor c.) Varactor and triac d.) Ferrite Isolator

13. (ECE Board Problem, November 2001) A very small band of frequency that is used to protect interference of adjacent frequency. a.) Guard b.) Carrier c.) Modulating d.) Tolerance 14. (ECE Board Problem, November 2001) It is a communication system operation where the receiving station controls the effective data transmission rate at the sending station. a.) Pacing b.) Polling c.) Handshaking d.) Contention 15. (ECE Board Problem, November 2001) Where is the AGC in the IF amplifier derived? a.) Mixer b.) Rf Amplifier c.) Detector d.) Local Oscillator 16. (ECE Board Problem, November 2002) What is the voltage in a line, open terminated at the end, quarter-wavelength from the termination? a.) Minimum b.) Maximum c.) The same d.) Increasing 17. (ECE Board Problem, November 2001) What is the cellular system used in Europe? a.) GSM b.) TACS

c.) AMPS d.) NMT 18. (ECE Board Problem, November 2001) Satellite revolution in the same direction as the earth's rotation. a.) Retrograde b.) Accelerated c.) Deccelerated d.) Posigrade 19. (ECE Board Problem, November 2001) What is meant by the term radiation resistance of an antenna? a.) The resistance in the trap coils to received signal. b.) An equipment resistance that would dissipate the same amount of power as that radiated from an antenna c.) The specific impedance of an antenna. d.) Losses in the antenna elements and feed line. 20. (ECE Board Problem, November 2001) How do you connect two digital terminal equipment (DTE) in the absence of a modem? a.) Line Bridging. b.) Direct connection with the use of a null modem. c.) Sharing of line. d.) Using a router. 21. (ECE Board Problem, April 2002) __________ demodulates an FM signal. a.) Frequency Discriminator b.) Frequency Multiplier c.) Diode Detector d.) IF Amplifier 22. (ECE Board Problem, April 2000) The effect of multi mode propagation caused the rays leaving the fiber to interfere constructively and destructively as they leave the end of the fiber, this effect is called ________. a.) multi mode Interference b.) Modal Delay Spreading c.) multi mode Effect d.) Single Modal Effect 23. (ECE Board Problem, November 2000)What is the maximum number of lines for any building other than a one or two story residential building to be required a service

entrance facility under ECE building code? a.) Two Lines b.) Five Lines c.) Three Lines d.) Not Required 24. (ECE Board Problem, November 2000) Which of the following is not part of the audio frequency section of the radio transmitter? a.) AF Voltage b.) Microphone c.) Master Oscillator d.) AF power Amplifier 25. (ECE Board Problem, November 2000) Which of the following solution will you prescribed to a telegraph transmitter power supply to avert a chirp? a.) Resonate power supply filters. b.) Decrease the voltage of power supply. c.) Regulate the power supply voltage d.) Decrease current output. 26. (ECE Board Problem, April 2000) What is the term for the ratio of actual velocity at which a signal travels through a line to the speed of light in a vacuum? a.) Surge Impedance b.) Characteristics Impedance c.) Standing Wave Ratio d.) Velocity Factor 27. (ECE Board Problem, April 1999) Which part of the HF marine antenna safety link is intended to be broken during the unusual movement of the ship? a.) Halkyard b.) Weak Part c.) Mainmast d.) Foremast 28. (ECE Board Problem, November 2002) A PCM has a 30 kHz sampling frequency. What is the maximum input frequency? a.) 15 kHz b.) 60 kHz c.) 45 kHz d.) 30 kHz

29. (ECE Board Problem, April 1999) What is the capture effect? a.) The weak signal received is the only demodulated signal. b.) All signals on a frequency are demodulated by an AM receiver. c.) All signals on a frequency are demodulated by an AM receiver. d.) The loudest signal received is the only demodulated signal. 30. (ECE Board Problem, April 2000) Which of the following microwave antenna is normally used when obtaining an omni – directional radiation requirement? a.) Grid Type b.) Whip c.) Bicone d.) Parabolic 31. (ECE Board Problem, April 1999) What is being measured in RADAR theory to complete the determination of a distance to a target or an object, after a high radio frequency signal is transmitted to a target? a.) Transmission time from the source to target. b.) Transmission time from target back to source. c.) Echo time of the object to the source. d.) Complete signal transmission from source and back. 32. (ECE Board Problem, April 2000) What is the radio horizon distance between a 150 ft. transmitting station and a 70 ft. receiving station? a.) 82.46 mi b.) 82.46 km c.) 29.15 km d.) 29.15 mi 33. (ECE Board Problem, November 2000) Telephone channel has a band-pass characteristics occupying the frequency range of _____. a.) 300-2700 Hz b.) 300-3400 Hz c.) 300-3000 Hz d.) 300-400 Hz

34. (ECE Board Problem, November 1999) This the Nordic analogue mobile radio telephone system originally used in Scandinavia.

a.) NMT b.) GSM c.) PCN d.) PCS 35. (ECE Board Problem, April 2000) When a signal bandwidth of a TV broadcast over the radio is lessen, using a technique that limits a picture frequency, this is referred to as ________. a.) Video Control b.) Interlaced Scanning c.) Demodulation d.) Line Scanninh 36. (ECE Board Problem, April 1999) These are bend of light wavelengths that are too short to be seen by the human eye. a.) Visible b.) Amber c.) Infrared d.) Ultraviolet 37. (ECE Board Problem, April 2000) How does the length of the director element of a parasitic element beam antenna compare with that of the driven element? a.) It is about 5% longer. b.) It is one-half as long. c.) It is twice as long. d.) It is about 5% shorter. 38. (ECE Board Problem, November 2001) Refers to the numeric ratio relating to the radiated signal strength of an antenna to that of another antenna. a.) Antenna Loss b.) Antenna Gain c.) Antenna Bandwidth d.) Antenna Efficiency 39. (ECE Board Problem, November 2001) What will happen if there is a great mismatch between the load and the source? a.) High SWR b.) Low SWR c.) Medium SWR d.) SWR of 1

40. (ECE Board Problem, November 2001) What is used to connect a computer if it is far from the host? a.) Modem b.) AVR c.) Waveguide d.) Transponder 41. (ECE Board Problem, November 2001) Range of frequency that an antenna will perform well. a.) Antenna Bandwidth b.) Antenna Beamwidth c.) Antenna Efficiency d.) Antenna Directivity 42. (ECE Board Problem, November 2001) What is the fastest memory of a computer? a.) RAM b.) Cache c.) Magnetic Disk d.) Magnetic Tape 43. (ECE Board Problem, November 2001) What composes the electromagnetic waves? a.) Electric and Magnetic Field b.) Acoustic and Water Wave c.) Current and Voltage d.) Pressure and Frequency 44. (ECE Board Problem, November 2001) One of the characteristics of an early facsimile machine which electromechanical device. a.) Receive start/stop bits to synchronize. b.) Using heat that would burn the image into heat. c.) Using tubes to amplify the signal. d.) Using fire to heat the thermal paper. 45. (ECE Board Problem, November 2001) What is the cable requirement for one or twostorey building that has more than five telephone lines? a.) Service Entrance b.) Service Cable c.) Building Cable d.) Residential Cable

46. (ECE Board Problem, November 2001) A transmission line consisting of center conductor, a plastic insulation, a fine wire braid shield and outer plastic insulation as a jacket. a.) coaxial cable b.) twin cable c.) wave guide d.) twisted pair 47. (ECE Board Problem, November 2001) The executive branch of government in-charge of policy making in telecommunication. a.) National Telecommunication Commission b.) Telecommunication Control Bureau c.) Department of Transportation and Communication d.) Bureau of Communication 48. (ECE Board Problem, November 2001) What is the dBSPL of an auditorium with contemporary music? a.) 95 – 100 dB b.) 40 – 50 dB c.) 50 – 60 dB d.) 70 – 80 dB 49. (ECE Board Problem, November 2001) What is the symbol designated for a frequency modulated carrier for a single telephony transmission? a.) F3E b.) F3F c.) G3F d.) G3E 50. (ECE Board Problem, November 2001) The layer that is responsible for sky wave propagation and the highest layer? a.) D b.) F2 c.) A d.) E 51. (ECE Board Problem, November 2001) Process of impressing lower intelligent frequency to higher frequency. a.) modulation b.) detection

c.) multiplexing d.) scrambling 52. (ECE Board Problem, November 2001) Find the suitable ground plane for a frequency of 220 MHz. a.) 0.5 m b.) 0.24 m c.) 0.34 m d.) 1.2 m 53. (ECE Board Problem, November 2001) The term used for the mechanism RADAR searchimg for an object. a.) scanning b.) tracing c.) lobing d.) nodding 54. (ECE Board Problem, November 2001) a.) variable capacitance b.) variable resistance c.) variable inductance d.) piezoelectric effect 55. (ECE Board Problem, November 2001) What do you call the telephone system connecting residence and business establishments? a.) Public Telephone System b.) Pay Phone System c.) Private Network System d.) Touch Tone System 56. (ECE Board Problem, April 2000) In Broadcasting, an area characterized to have no interference but wit fading or intermittent variations in intensity is _______. a.) Primary Service Area b.) Intermediate Service Area c.) Tertiary Service Area d.) Secondary Service Area 57. (ECE Board Problem, April 2002) Information capacity is proportional. a.) bandwidth b.) noise

c.) power d.) flux 58. (ECE Board Problem, April 2002) What is the number of lines per field in an NTSC TV? a.) 525 b.) 262.5 c.) 625 d.) 312.5 59. (ECE Board Problem, April 2002) It refers to the time required for a signal to complete one cycle. a.) Wavelength b.) Frequency c.) Amplitude d.) Period 60. (ECE Board Problem, April 2002) What happens when the separation between two conductors having the same diameter decreases? a.) The characteristic impedance decreases. b.) The characteristic impedance increases, c.) The characteristic impedance does not change. d.) Cannot be determined 61. (ECE Board Problem, November 2001) The government entity that regulates the cable television industry in the Philippines. a.) Executive Commission b.) House of Representatives c.) NTC d.) DOTC 62. (ECE Board Problem, November 2001) A modulation which is amplitude modulated that consist of recurrent pulses. a.) PAM b.) PWM c.) PPM d.) AM 63. (ECE Board Problem, November 2001) Which of the following consist of twp of the three primary colors in television signal? a.)red, b)violet,c)yellow, and d)blue. a.) a and b

b.) b and c c.) c and d d.) a and d 64. (ECE Board Problem, November 2001) Which of the navigational equipment which utilizes the principle of RADAR but is use in underwater? a.) TACAN b.) SONAR c.) TASI d.) RADAR 65. (ECE Board Problem, November 2001) How can cross – modulation in a receiver be reduced? a.) Adjust the pass band tuning. b.) Increase RF amplifier gain and decrease AF amplifier gain c.) Installing a filter at the receiver d.) Using a better antenna 66. (ECE Board Problem, November 2001) The circuit that convert signal in order that it can be fed to the medium suitable for transmission. a.) Modulator b.) Mixer c.) Receiver d.) Transmitter 67. (ECE Board Problem, November 2001) A type of Class C amplifier which has 1 to 10 times the gain of input used to generate frequency multiple of the fundamental frequency. a.) Frequency Generator b.) Frequency Multiplier c.) Frequency Amplifier d.) Frequency Divider 68. (ECE Board Problem, November 2001) The definition of modulation index: a.) The radio of deviation frequency and modulating b.) The ratio of the maximum deviation frequency and maximum modulating frequency c.) The ratio of actual deviation to the maximum deviation d.) The ratio of the maximum deviation to the actual deviation 69. (ECE Board Problem, November 2001) One of the following can be best attained by a trap antenna in radio communication?

a.) Increase transmitter gain b.) Directionality c.) Effective filter to noise signal d.) Multi frequency band operation 70. (ECE Board Problem, November 2000)when we talk of the study of acoustics, a sound is considered _____wave. a.) Circular b.) Light c.) Laser d.) Longitudinal 71. (ECE Board Problem, November 1999) One of the major components required under the global maritime distress and safety system. a.) Provision of Morse code b.) Provision of radio telegraph operator c.) Provision of facsmile d.) Provision of radio personnel 72. (ECE Board Problem, November 1999) A resultant effect in launching a satellite from the earth caused by both forward motion away from the earth that produces inertia tending the satellite to travel in straight line upwards and the gravitational pull towards the earth is referred to as _______. a.) Centripetal acceleration b.) Gravity c.) Weight of satellite d.) Satellite Speed 73. (ECE Board Problem, April 2000) A RADAR set receiver has normally a ________ mixer stage. a.) Tunnel diode b.) FET c.) Class A d.) Silicon Crystal 74. (ECE Board Problem, April 1999) Refers to a connector that normally connects RG – 213 coaxial cable to an HF transceiver. a.) N-type Cable b.) F-type Cable c.) PL-259 d.) BNC

75. (ECE Board Problem, November 2000) Which of the following refers to the bandwidth of optical fiber? a.) 1 Hz-30,000 Hz b.) 1 kHz-300 kHz c.) 1MHz-300 MHz d.) 1MHz-500MHz 76. (ECE Board Problem, April 1999) How many commissioners does the National Telecommunications Commission have? a.) 1 b.) 5 c.) 3 d.) 2

77. (ECE Board Problem, November 2000) Which one is referred to the reduction of receiver gain caused by strong signal from nearby transmission of adjacent frequency? a.) Intermodulation b.) Quieting c.) Fading d.) Desensitizing 78. (ECE Board Problem, April 2000) Transmission of information through a communication modem is intended to transmit digital information over which of the following type of communication medium? a.) b.) c.) d.)

Digital Hybrid Radio Analog

79. (ECE Board Problem, April 1999) Determine from the following an advantage using a trap antenna. a.) b.) c.) d.)

It has directivity in the high frequency bands. Can be used for multiband operation. Minimizes harmonic radiation. Has high gain.

80. (ECE Board Problem, November 2002) What do you call a circuit in PCM wherein the instantaneous sinusoidal wave is regular sample and converted to a discrete amplitude levels? a.)analog to digital converter b.) sample and hold c.) modem d.) multiplexer 81. (ECE Board Problem, April 1999) Determine from the following, possible cause for a slow drift of frequency in self-excited transmitter oscillator circuits resulting to poor frequency stability. a.)Faulty capacitors, resistors, tubes or transistors. b.) Loose shielding. c.) Heating in the oscillator device causing a change in electrical characteristics. d.) Loose connections in the oscillator, amplifier or antenna circuits. 82. (ECE Board Problem, November 2000) Which of the following penalty is provided under the existing telecommunications law, should an international carrier unable to comply with its obligation to provide local exchange service in un-served and underserved areas within three years from grant of authority? a.)Financial penalty in accordance with existing schedules. b.)Cancellation of its authority. c.) Given one year to comply. d.) Given two years to comply. 83. (ECE Board Problem, April 2000) In basic transmitter such as CW transmission, the rounding off of square wave emission will reduce________. a.) b.) c.) d.)

Reach Voltage Bandwidth Transmitter power

84. (ECE Board Problem, November 1999) Refers to one possible cause for an abrupt frequency variation in a self-excited transmitter oscillator circuits resulting to a poor frequency stability to hold a constant oscillation. a.) b.) c.) d.)

Poor soldered connections. Heating of capacitor in the oscillator. DC and RF ac heating of resistors, which cause change in values. Aging which cause change condition in parts characteristics.

85. (ECE Board Problem, November 2000)which of the following is referred to the SYN character of ASCII code? a.)32H b.)16H c.)64H d.)8H 86. (ECE Board Problem, November 1999)In a basic radio transmitter, what is the main disadvantage of a single-tube transmitter? a.)Frequency Instability b.)Non-portable c.)Heating Effect d.)Bulky 87. (ECE Board Problem, April 2000) One of the following is considered the largest source of signal power loss in the use of fiber optic as a communication medium such as due to misalignment. a.) Bending b.) Scattering c.) Connection d.) Absorption 88. (ECE Board Problem, November 2000) Statement, which best describe a mixing process in radio communication. a.) Process of eliminating noise through phase differentiation. b.) Producing sum and difference of two frequencies from a combination of two signals. c.) Processing of eliminating noise through phase comparison. d.) Combination of two signals to form three or more output signals. 89. (ECE Board Problem, November 2001)What is the input impedance equivalent of an open-ended transmission line which is longer than a quarter wavelength? a.) Open equivalent b.) Equivalent to reactive circuit c.) As resistive equivalent d.) As pure inductor 90. (ECE Board Problem, November 2000) How would you isolate data communications faults in a basic error determination technique? a.) Test each cards.

b.) Simulate the loop. c.) Test each repeater. d.) Carry out loopback test. 91. (ECE Board Problem, April 2000) Which of the following describes its system services control point, logical units and physical units as network addressable units in a data network? a.) Digital Network Architecture b.) Internetworking c.) Interconnection Point d.) System Network Architecture 92. (ECE Board Problem, November 2000) A telecommunications law that deregulates the paging services in the country. a.) E. O. 125 b.) Act 3846 c.) Act 3396 d.) R.A. 7925

93. (ECE Board Problem, April 2000) What refers to breaking up the data into blocks with some bounded size? a.) Framing b.) Segmentation c.) Encapsulation d.) Packing 94. (ECE Board Problem, November 2001) What is the apogee of a geosynchronous satellite’s temporary orbit before be placed in the geosynchronous orbit? a.) 50,000 mi b.) 40,000 mi c.) 22,300 mi d.) 30,000 mi 95. (ECE Board Problem, November 2001) A device used in television broadcast that prevents any FM signal from entering into the visual transmitter and vice versa. a.) Duplexer b.) Mixer c.) Diplexer d.) Synchronizer

96. (ECE Board Problem, November 1999) A sound intensity that could cause painful sensation in the human ear. a.) Threshold of Sense b.) Threshold of Pain c.) Hearing Threshold d.) Sensation Intensity 97. (ECE Board Problem, April 1999) What is the first symbol of radio signal emission having an amplitude modulated main carrier single sideband suppressed carrier? a.) C b.) A c.) J d.) H 98. (ECE Board Problem, November 1999) What us the baseband frequency of standard FDM basic super group? a.) b.) c.) d.)

300 to 600 kHz 312 to 552 kHz 60 to 2540 kHz 60 to 180 kHz

99. (ECE Board Problem, November 1999) Very High (radio) Frequency in the spectrum refers to _______ waves. a.) b.) c.) d.)

Centimetric Hectometric Kilometric Metric

100. (ECE Board Problem, April 1999) What wave trap frequency is used in the video amplifier? a.) b.) c.) d.)

39.75 MHz 41.25 MHz 4.5 MHz 47.25 MHz

101.(ECE Board Problem, November 2000) Which of the following best described the primary source of errors in the transmission of data over telephone networks? a.) Thermal Noise b.) Crosstalk c.) Impulse Noise

d.) Intermodulation

102. (ECE Board Problem, April 1999) Which part of the HF marine antenna handles the broken safety link, in case it results collision, grounding or storm? a.) b.) c.) d.)

The lead-in. The foremast. The strong part. The halyard.

103. (ECE Board Problem, April 2000) A reduction in receiver sensitivity caused by unwanted high-level adjacent channel signals. a.) b.) c.) d.)

Intermodulation Overloading Interference Desensitizing

104. (ECE Board Problem, November 2000) Which of the following system uses frequency band 870-890 MHz as a transmit band of its base station? a.) b.) c.) d.)

Total Access Communication System (TACS) Nordic Mobile Telephone (NMT) Public Mobile System (PMS) Advance Mobile Phone Services (AMPS)

105. (ECE Board Problem, November 2000) Refers to a mobile earth station in the mobilesatellite service located on board ship. a.) b.) c.) d.)

Mobile Station Ship Station Ship Earth Station Mobile Satellite Station

106. (ECE Board Problem, November 2002) What is the electric field strength in millivolts per meter if the transmitted power is 30kW, at a distance of 5km? a.) b.) c.) d.)

120 mV/m 190 mV/m 150 mV/m 30 mV/m

107. (ECE Board Problem, November 2000) Frequency band where Total Access Communication System is allocated. a.) b.) c.) d.)

86-869 MHz; 821-824 MHz 870-890 MHz; 825-845 MHz 851-866 MHz; 806-821 MHz 935-960 MHz; 890-915 MHz

108. (ECE Board Problem, November 2000) Which of the following is used as a standard channel spacing for AM broadcast in the Philippines? a.) b.) c.) d.)

25 kHz 12.5 kHz 40 kHz 9 kHz

109. (ECE Board Problem, November 2000) What is the frequency separation between the aural carrier and the lower limits of the total channel band of a monochrome TV broadcast? a.) b.) c.) d.)

1.25 MHz 4.5 MHz 3.0 MHz 5.75 MHz

110. (ECE Board Problem, November 2000) Which salellite transponder has the most number of mixers? a.) b.) c.) d.)

Regenerative Broadband Double-Conversion Channelized

111. (ECE Board Problem, November 2000) An advantage of fiber optic co-axial cable as a result of coupling signals from one to the other due to changing magnetic field in one or both. a.) b.) c.) d.)

Feedback Crosstalk Electric Hazard Shielding

112. (ECE Board Problem, April 2001) How can even-order harmonics be reduced or prevented in transmitter amplifier design? a.) By using a push-push amplifier b.) By using push-pull amplifier c.) By operating Class C

d.) By operating Class AB 113. (ECE Board Problem, April 2002) With which emission type is the capture effect most pronounced? a.) b.) c.) d.)

FM SSB AM CW

114. (ECE Board Problem, April 2002)What is the term used to refer to the reception blockage of one FM-phone signal by another FM-phone signal? a.) b.) c.) d.)

Desensitization Cross-modulation Interference Capture Effect Frequency Discrimination

115. (ECE Board Problem, April 2002) What is the primary purpose of an RF amplifier in a receiver? a.) b.) c.) d.)

To provide most of the receiver gain. To develop the AGC voltage. To improve the receiver’s noise figure. To vary\ the receiver image rejection by utilizing the AGC.

116. (ECE Board Problem, April 2002)What is the product of the power fed to the antenna and its power gain? a.) b.) c.) d.)

Antenna Power ERP PEP Peak Power

117. (ECE Board Problem, April 1999) What is the reason why Hertz antenna is not normally used to radio station or receiver or transmitter antenna that has frequency below 2MHz? a.) b.) c.) d.)

The antenna receives more inter-modulation signal. The antenna receive side becomes non-receptive. The antenna will be physically very small. The antenna will be physically very large.

118. (ECE Board Problem, November 1999) In the study of transmission cable, twin lead is also referred to as________. a.) Twisted pair

b.) Double cable c.) Ribbon cable d.) Open pair 119. (ECE Board Problem, November 1999) In an open architecture concept of data communication, one of the following is not a function of a control layer. a.) b.) c.) d.)

Fault correction Congestion control Fault detection Integrity of data

120. (ECE Board Problem, November 1999)What are the two legislative function of the International Telecommunications Union in its international conference issues on orbital resources? a.) Assign frequencies and organizes conferences. b.) Allocates frequency bands for the services and determine the principle of distribution of orbit/spectrum resources. c.) Determine the principles of spectrum distribution and assignment of frequencies. d.) Conduct conferences and allocation of orbital slot. 121. (ECE Board Problem, April 2002)What transmission medium is capable of carrying up to 10Gbps capacity? a.) b.) c.) d.)

Twisted pair Optical fiber Coax Microwave link

122. (ECE Board Problem, April 2002) What is the controlling node of a star topology system? a.) b.) c.) d.)

Modem Codec Hub ADC

123. (ECE Board Problem, April 2002) What is the most efficient topology used by small business organization? a.) b.) c.) d.)

Mesh Star Bus Ring

124. (ECE Board Problem, April 2002)Which of the following network topology has the fastest speed? a.) b.) c.) d.)

Star Ring Bus Mesh

125. (ECE Board Problem, April 2002) The latest and most advanced equipment in data communications is a/an___________. a.) b.) c.) d.)

Amplifier Simulator Protocol analyzer Spectrum analyzer

126. (ECE Board Problem, April 2002) Which has the highest priority in radio telephone communication? a.) b.) c.) d.)

Distress Safety Urgency Roger

127. (ECE Board Problem, April 2002) In satellite communications, what is the frequency of the V-band? a.) b.) c.) d.)

27-40 GHz 4-8 GHz 8-12GHz 40-75 GHz

128. (ECE Board Problem, April 2002) What is meant by the term antenna gain? a.) The numerical ratio relating the radiated signal strength of an antenna to that of another antenna. b.) The ratio of the signal in the forward direction to the signal in the back direction. c.) The ratio of the amount of power to produce by the antenna compared to the output power of the transmitter. d.) The final amplifier gain minus the transmission line losses. 129. (ECE Board Problem, April 2002) What is an advantage using a trap antenna? a.) It has antenna gain b.) It minimizes harmonic radiation c.) It has high directivity in the high frequency bands

d.) It may be used for multiband operations 130. (ECE Board Problem, April 2002) What is the wavelength of a shorted stub used to absorb even harmonics? a.) b.) c.) d.)

0.5 wavelength 1/3 wavelength 0.25 wavelength 1/8 wavelength

131. (ECE Board Problem, November 2002) Who coined the term fiber optics? a.) b.) c.) d.)

Hansell Hopkins N.S. Kapany Van heel

132. (ECE Board Problem, April 2002) How does the length of the reflector element of a parasitic beam antenna compare with that of a driven element? a.) b.) c.) d.)

It is about 5% longer. It is about 5% shorter It is twice as long It is one-half as long

133. (ECE Board Problem, April 2001) In a half wave antenna, where are the current nodes? a.) b.) c.) d.)

At the ends At the center One-half of the way from the feed point toward the end. Three-quarters of the way from the feed point toward the end.

134. (ECE Board Problem, April 2002) Why is a loading coil often used with an HF mobile antenna? a.) b.) c.) d.)

To improve reception To lower the losses To lower the Q. To tune out the capacitive resistance.

135. (ECE Board Problem, April 2002) What is a frequency discriminator? a.) b.) c.) d.)

A circuit for detecting FM signals A circuit for filtering two closely adjacent signals. An automatic band switching circuit. An FM generator.

136. (ECE Board Problem, April 2002) What is the period of a wave? a.) b.) c.) d.)

The time required to complete one cycle. The number of degrees in one cycle. The number of zero crossing in one cycle. The amplitude of the wave.

137. (ECE Board Problem, April 2002) The implementing guidelines on international satellite communications is___________. a.) b.) c.) d.)

EO 467 EO 846 DO 11 DO 88

138. (ECE Board Problem, April 2002) What was implemented in 1999 which has the purpose of aiding the maritime navigation using satellite as well as advanced terrestrial communication system? a.) b.) c.) d.)

GMDSS AMPS GLONASS NAVSTAR

139. (ECE Board Problem, April 2002) Which of the following is not a DTE? a.) b.) c.) d.)

Telephone set Computer Bridge Printer

140. (ECE Board Problem, April 2002)What is the transmission of data through a different time slots? a.) b.) c.) d.)

TDM FDM WDM CDM

141. (ECE Board Problem, April 2002) What is the parameter that affects the computation of image frequency? a.) Q b.) fLO c.) fIF

d.) D e.) 142. (ECE Board Problem, April 2002) Which of the following could not be observed in a microwave communications? a.) b.) c.) d.)

LOS Wide BW Better Signal Penetration Directional Antenna

143. (ECE Board Problem, April 2002) The service area where the signal is subject to fading with no objectionable interference. a.) b.) c.) d.)

Primary service area Secondary service area Intermittent service area Quarternary service area

144. (ECE Board Problem, April 2002) By examining the following antenna type, determine which is properly terminated? a.) b.) c.) d.)

Non-resonant Type Half-wave Dipole Whip antenna Type Resonant Type

145. (ECE Board Problem, April 2001) What is the third letter symbol in the emission designation for telemetry? a.) b.) c.) d.)

F B D N

146. (ECE Board Problem, April 2002) What is the frequency tolerance of FM broadcasting? a.) b.) c.) d.)

25 kHz 20 kHz 2 kHz 30 kHz

147. (ECE Board Problem, April 2001) Which of the following is commonly used search engine? a.) .edu

b.) www c.) .org d.) Excite 148. (ECE Board Problem, April 2001)When the electric field is perpendicular to the surface of the earth, what is the polarization of the electromagnetic wave? a.) b.) c.) d.)

Vertical Horizontal Circular Elliptical

149. (ECE Board Problem, April 2001) What is the deviation ratio of an FM signal if the maximum allowable deviation is 12 kHz and the maximum intelligence frequency is 4 kHz? a.) b.) c.) d.)

3 48 2/3 1/3

150. (ECE Board Problem, April 2002) What is the typical satellite communications bandwidth? a.) b.) c.) d.)

20 MHz 30 MHz 40 MHz 500 MHz

151. (ECE Board Problem, April 2001) the following are not used in radio communications, except________. a.) b.) c.) d.)

Infrared Cosmic X-ray Gamma

152. (ECE Board Problem, April 2001) A modem which can be used to send data and fax. a.) b.) c.) d.)

Bell 212A ARQ Fax modem Data modem

153. (ECE Board Problem, April 2001) What is the output of a balanced modulator. a.) SSB

b.) DSB c.) ISB d.) VSB 154. (ECE Board Problem, April 2002) An emission technique where the total current will be twice as much when the modulation index is doubled. a.) J3E b.) H3E c.) A3E d.) R3E 155. (ECE Board Problem, April 2001) Which of the following uses frequency modulator circuit? a.) b.) c.) d.)

A3E F3E H3E R3E

156. (ECE Board Problem, April 2002) What is used to display harmonics and fundamental frequency? a.) b.) c.) d.)

Oscilloscope Spectrum Analyzer Wattmeter Ohmmeter

157. (ECE Board Problem, November 2002) What is the free space loss, in dB, of a microwave system when the frequency is 6 GHz at 40km apart? a.) b.) c.) d.)

170 dB 150 dB 160 dB 140 dB

158. (ECE Board Problem, April 2001) When the signal becomes weak, the base will request the MTSO to find another site. a.) b.) c.) d.)

Roaming Hand-off Frequency Re-use Cell splitting

159. (ECE Board Problem, April 2001) What is the interference between the switching office and the mobile unit.

a.) b.) c.) d.)

Cell sites MTSO Microwave link Base station

160. (ECE Board Problem, April 2001) Which is not an omni-directional antenna? a.) b.) c.) d.)

Vertical folded dipole Discone Rhombic Marconi

161. (ECE Board Problem, April 2001) Which satellite band is affected by VHF signals? a.) b.) c.) d.)

L C P Ku

162. (ECE Board Problem, April 2001) What is produced by over-modulation in AM? a.) b.) c.) d.)

Sidebands Jitter Glitch Spurious Signal

163. (ECE Board Problem, April 2001)_____ is the process of sending out the information in all directions. a.) b.) c.) d.)

Navigation Broadcasting Acoustics Telemetry

164. (ECE Board Problem, April 2001) How do you increase the electrical length of an antenna? a.) b.) c.) d.)

Add an inductor in parallel Add an inductor in series Add a capacitor in series Add a resistor in series.

165. (ECE Board Problem, April 2001) What is the usual electrical length of a driven element in HF beam antenna? a.) ¼ wavelength

b.) ½ wavelength c.) ¾ wavelength d.) 1 wavelength 166. (ECE Board Problem, April 2002) What is the point in the satellite as it crosses the equator? a.) b.) c.) d.)

Apogee Node Perigee Orbit

167. (ECE Board Problem, November 2001) Direct Distance Dialing is________. a.) Private line b.) Public line c.) Lease line d.) Dial-up 168. (ECE Board Problem, November 2001)A path wherein a satellite crosses in the equator heading south. a.) b.) c.) d.)

Ascending node Descending node Orbital Polar

169. (ECE Board Problem, November 2001) In what frequency band does 4-6 GHz fall in the satellite communications? a.) b.) c.) d.)

C-Band L-Band X-band K-band

170. (ECE Board Problem, November 2001) A computer network found in the same building. a.) b.) c.) d.)

Local area network Wide area network Metropolitan area network PLL

171. (ECE Board Problem, April 2002) Which of the following antenna feedline can easily be buried underground for a distance without adverse effects? a.) Waveguide b.) Twisted pair

c.) Coaxial cable d.) Twin lead 172. (ECE Board Problem, April 1999) In the study of wave propagation, a condition at which zero absorption of radio waves is describe as__________. a.) b.) c.) d.)

Zero reflection medium Neutral medium Free space medium Non-active medium

173. (ECE Board Problem, November 1999) Which of the following in the radio emission designation refers to the first symbol? a.) b.) c.) d.)

Nature of signal modulating the main carrier Type of modulation of the main carrier Emission bandwidth Type of information

174. (ECE Board Problem, November 2000) The process of exchanging predetermine codes and signals in telecommunications between two data terminals to establish a connection is called. a.) b.) c.) d.)

Hands-off Polling Handshake Demodulation

175. (ECE Board Problem, April 2000) It is an electronic instrument which can be referred to as a miniature radio transmitter and can be made to generate signals at any desired frequency, normally it is used for test purposes. a.) b.) c.) d.)

Volt-ohm milliammeter Signal generator Oscilloscope Wavemeter

176. (ECE Board Problem, April 1999) A network interconnection facility which is used to interconnect networks whose architectures are entirely different is called________. a.) b.) c.) d.)

Bridge Router Gateway Repeater

177. (ECE Board Problem, November 1999) Type of multi-channel transmission in the optic

fiber communication that uses a twisted pair coupler to transmit two signals of different wavelengths. a.) b.) c.) d.)

Frequency-division multiplexing Forward-division multiplexing Pulse-code multiplexing Time-division multiplexing

178. (ECE Board Problem, April 2000) These are the rules in data communications intended for establishing data links and message interpretation. a.) b.) c.) d.)

Mode EIA Rules CCIR Rules Protocol

179. (ECE Board Problem, November 1999) A radio station in mobile service intended to be used while in motion or during halts at unspecified points. a.) b.) c.) d.)

Maritime radio station Land mobile station Mobile station Mobile earth station

180. (ECE Board Problem, April 1999) What is the advantage on the TV receiver audio by employing FM audio and AM video on the television transmitter? a.) b.) c.) d.)

FM receiver rejects static noise FM receiver is basically insensitive to amplitude modulation Fm receiver is basically insensitive to amplitude modulation FM receiver is clear over AM.

181. (ECE Board Problem, April 1999) What does the elastic store refereed to in the time division multiplex system used in fiber optic? a.) b.) c.) d.)

Amplifier Holding memory Reflector Timer

182. (ECE Board Problem, November 1999) What are the two general categories of methods for generating emission F3E?

a.) The only way to produce an emission F3E signal is with a reactance modulator on the oscillator. b.) The only way to produce an emission F3E signal is with a balanced modulator on the oscillator. c.) The only way to produce an emission F3E signal is with a balanced modulator on the audio amplifier. d.) The only way to produce an emission F3E signal is with a reactance modulator on the final amplifier.

183. (ECE Board Problem, November 2002) Pressure us measured in terms of Pascal, microbar, or__________. a.) b.) c.) d.)

Newtons Newtons per meter Newtons per meter squared Pascal per meter squared

184. (ECE Board Problem, April 1999) What is the function of the network layer in the computer communications? a.) b.) c.) d.)

Parity control Direction control Congestion control Error control

185. (ECE Board Problem, April 2000) Which of the following limits the top speed of transmitting information in fiber optic? a.) b.) c.) d.)

Noise Detector speed Time domain Refractor index

186. (ECE Board Problem, April 1999) A mobile telephone system which uses an analogue cellular radio standard which was superseded by Advanced Mobile Phone System in the U.S. a.) b.) c.) d.)

TDMA IMTS CDMA D-AMPS

187. (ECE Board Problem, November 2000) Satellite that rotates around the earth in a low altitude elliptical or circular pattern.

a.) b.) c.) d.)

Geosynchronous Satellite Prograde Nonsynchronous satellite Apogee

188. (ECE Board Problem, April 2000) One of the following processes or system best describe an example of a pilot tone system normally use in commercial broadcast FM stations. a.) b.) c.) d.)

Time division Frequency division Stereo multiplex QSK

189. (ECE Board Problem, November 2000) What is the main reason why coaxial cable is not used in microwave signal transmission? a.) b.) c.) d.)

Wide bandwidth Number of repeaters Low impedance High attenuation

190. (ECE Board Problem, April 2000) Refers to a characteristic of a multimode fiber optic. a.) Cladding thickness is less than the radius of the core and diameter of the core must be greater than the wavelength of the light to be carried. b.) Cladding thickness is greater than the radius of the core and the diameter of the core must be lesser than the wavelength of the light to be carried. c.) Cladding thickness is less than the radius of the core and the diameter of the core must be lesser than the wavelength of the light to be carried. d.) Cladding thickness is greater than the radius of the core and the diameter of the core must be much greater than the wavelength of the light to be carried. 191. (ECE Board Problem, April 2000) Two or more LAN linked together over the wide geographical area. a) b) c) d)

HAN WAN MAN RAN

192. (ECE Board Problem, April 2000) A process of sending data in computing technology by asking each remote computer terminal one at a time if such computer terminal has data to send. a) Selection b) Networking

c) Polling d) Coding 193. (ECE Board Problem, November 1999) What is the primary purpose of an RF amplifier in receiver? a) b) c) d)

To vary the receiver image rejection by utilizing the AGC. To provide the most receiver gain. To develop the AGC voltage. To improve the receiver’s noise figure.

194. (ECE Board Problem, April 2000) Why are fiber optic cables considered less expensive compared to coaxial cables in communication system? a) b) c) d)

Coaxial is very expensive than fiber optic. Due to weight. Installation cost of coaxial. Use of less repeaters.

195. (ECE Board Problem, November 1999) Refers to as a linkage by wire, radio, satellite or other means, of two or more telecommunications carrier or operators with one another for the purpose of allowing or enabling the subscriber of one carrier or operator to access or reach the subscribers of the other carrier or operator. a) Interconnection b) Toll patching c) Gateway d) Outside plant sharing 196. (ECE Board Problem, November 1999) In order to have an effective radio antenna the design of its radiator must have a minimum length equivalent to________. a) b) c) d)

Λ/10 Λ/4 Λ/14 Λ/6

197. (ECE Board Problem, April 2000) Referred as the forward link channel of the cellular duplex system. a) b) c) d)

Cell to Cell Mobile to Mobile unit Mobile to Cell unit Cell to Mobile unit

198. (ECE Board Problem, November 2000) Method of a telecommunications operation where transmission can be made simultaneously in both direction of a channel.

a) b) c) d)

Semi-duplex Operation Duplex Operation Half-duplex Operation Simplex Operation

199. (ECE Board Problem, April 2000) Which symbol in radio signal emission designation is referred to type of modulation of the main carrier? a) b) c) d)

Second Fourth Third First

200. (ECE Board Problem, November 2000) What type of emission is produced when an amplitude-modulated transmitter is modulated by a facsimile signal? a. b. c. d.

A3F F3 A3C F3F

201. (ECE Board Problem, November 2000) A point in the satellite orbit known to be the closest location to the surface of the earth. a) b) c) d)

Zenith Perigee Apogee Azimuth

202. (ECE Board Problem, November 2000) Determine from the following the common use of DSB in broadcast and telecommunication. a) b) c) d)

Satellite Communication FM/TV Stereo Two-Way Communication Telephone System 203. (ECE Board Problem, November 2000) Determine the image frequency of a broadcast band receiver using a 455 kHz IF tuned to 630kHz-DZMM.

a) b) c) d)

1085 kHz 1530 kHz 1540 kHz 1715 kHz

204. (ECE Board Problem, November 2000) A phenomenon which causes the speed of light rays propagation in the fiber material changes, as it passes through different medium in the fiber. a) b) c) d)

Bending Refraction Diffraction Reflection 205. (ECE Board Problem, November 1999) An electronic equipment used in the radio communication to measure standing wave ratio.

a) b) c) d)

Radio meter Reflectometer Oscilloscope Wave Meter

206. (ECE Board Problem, November 2000) Referred as an effect of parasitic elements in an antenna system. a) b) c) d)

Decrease its directivity Makes the antenna omni directional Makes the antenna isotropic Increase its directivity 207. (ECE Board Problem, November 2000) Radio wave concentration in the direction of the signal emitted by a directional antenna.

a) b) c) d)

Side lobe radiation Major lobe radiation Back lobe radiation Transmitted signal

208. (ECE Board Problem, November 2002) What is the main principle used by ITU in determining the distribution of the orbit/ spectrum resources? a) b) c) d)

Depending on the geographical boundary of a nation Efficient use and equitable access. Depending on a national sovereignty declaration Equal distribution

209. (ECE Board Problem, April 2000) What quarter-wave transformer will match a 600Ω transmission line to an antenna whose value is 70 Ω? a.) b.) c.) d.)

205 Ω 502 Ω 600 Ω 75 Ω

210. (ECE Board Problem, November 1999) Let us consider a frequency range of 405.0125 MHz to 405.0875 MHz and a 25 kHz channeling plan, determine the center frequency of the second channel from the lower limit. a.) b.) c.) d.)

405.050 MHz 405.0125 MHz 405.025 MHz 405.011 MHz

211. (ECE Board Problem, April 2000) What is the reason why 5/8-whip vertical antenna is of advantage than quarter wave vertical whip antenna? a.) b.) c.) d.)

Less interference Can handle high power signal More gain Flexible

212. (ECE Board Problem, April 1999) Why is it that almost all switching type integrated data communication circuits are called digital? a.) b.) c.) d.)

They are mostly on/off devices. They process digital information They are small type They are integrated circuits.

213. (ECE Board Problem, November 2000)Which of the following shall be complied by an international ship pursuant to the global maritime distress and safety system implemented last 1999? a.) b.) c.) d.)

A facsimile A radio personnel A Morse code A radio telegraph operator

214. (ECE Board Problem, November 2000) Bit rate of a telecommunications carrier T2. a.) b.) c.) d.)

7.312 Mb/s 7.318 Mb/s 6.511 Mb/s 6.312 Mb/s

215. (ECE Board Problem, November 2000) In propagation of radio signals through an aerial at what angle does not magnetic field is positioned with reference to the direction of propagation. a.) b.) c.) d.)

180 90 0 45

216. (ECE Board Problem, April 1999) What is the frequency separation between the visual carrier and the upper limits of its total channel bandwidth of a monochrome TV broadcast? a.) b.) c.) d.)

4.5 MHz 4.75 MHz 3.0 MHz 1.25 MHz

217. (ECE Board Problem, November 2000) In radio communications, the term trap antenna is referred to in one of the following statements. a.) b.) c.) d.)

Antenna with wide beam width Those antennas with high rejecting capability to interfering signals. Those antenna with long coverage in terms of distance Antenna which can be used on more than one band due to the use of parallel LC networks.

218. (ECE Board Problem, April 1999) What is the range of an AM broadcast frequency tolerance above or below its assigned frequency? a.) b.) c.) d.)

25kHz 20 Hz 60 kHz 120 kHz

219. (ECE Board Problem, April 2000) Which part of the housing system in ECE code is a circular opening through the floor structure to allow the passage of cable and wire.

a.) b.) c.) d.)

Insert Sleeve Raceway Slot

220. (ECE Board Problem, April 2000) What is the length of a simple quarter wave antenna using a VHF frequency of 150.55 MHz? a.) b.) c.) d.)

0.98 ft. 1.24 ft. 1.80 ft. 1.55 ft.

221. (ECE Board Problem, November 2000) In the study of acoustics, the velocity of sound is dependent to one of the following. a.) b.) c.) d.)

Temperature Loudness Source of sound Properties of the medium

222. (ECE Board Problem, April 1999) Which of the following is not considered as one of the causes for the loss of signal power as light travels through a fiber optic? a.) b.) c.) d.)

Scattering Intermodulation Fiber bending Absorption

223. (ECE Board Problem, November 1999) Referred to as a light source of fiber optic, which supplies power level of 5 to 7 mW and having a narrow spectrum of emission. a.) b.) c.) d.)

Injection laser diode Photodiode Light emitting diode Crystal diode

224. (ECE Board Problem, April 2000) A digital mobile telephone system, which is called European derivative of Global System for Mobile Communication System operating at a higher frequency band. a.) b.) c.) d.)

E-TACS IMTS DCS-1800 TACS

225. (ECE Board Problem, April 1999) Communication through the use of a modem is transmission of__________ data information in ____________ medium.

a.) b.) c.) d.)

Analog, analog Analog, digital Digital, analog Digital, digital

226. (ECE Board Problem, November 1999) What type of emission is produced when amplitude modulated transmitter is modulated by a television signal? a.) b.) c.) d.)

A3F F3C F3F A3C

227. (ECE Board Problem, April 1999) A term, used in radio communication defining the frequency band from the lowest to its highest limits, designed to be passed through a component, system or a device with an acceptable attenuation. a.) b.) c.) d.)

Allocated band Baseband Bandwidth Transmitted signal

228. (ECE Board Problem, April 2000) Which body in the present ITU structure took the place of CCITT? a.) b.) c.) d.)

ITU-R ITU-D ITU-T RAG

229. (ECE Board Problem, November 2002) What is the frequency range of VLF? a.) b.) c.) d.)

10-10 kHz 30-300 kHz 300-3000 kHz 3-30 kHz

230. (ECE Board Problem, April 1999) What is a wave front? a.) b.) c.) d.)

A voltage pulse in a conductor A current pulse in the conductor A voltage pulse across a resistor A fixed point in an electromagnetic wave

231. (ECE Board Problem, November 2000) How would you best describe an example of a pilot tone system use in commercial frequency modulation broadcast radio stations?

a.) b.) c.) d.)

Frequency simplex Time division Stereo multiplex QSK

232. (ECE Board Problem, April 1999) Kind of broadcasting system where television programs are transmitted directly to home/user receivers via satellite, thus making the reception cover not only individuals in their homes but other places as well. a.) b.) c.) d.)

Pay TV Direct to Home TV Cable TV VHF TV

233. (ECE Board Problem, November 1999) In telecommunication, what do we call the difference in the voltage level between a driver and a terminator? a.) b.) c.) d.)

System gain Noise margin System loss Noise difference

234. (ECE Board Problem, April 2000) Why is parallel transfer method in data transmission faster then serial? a.) b.) c.) d.)

Wider channel bandwidth Bits are transferred simultaneously Bits are lighter in parallel Due to faster changes in symbol

235. (ECE Board Problem, November 2000) Radio frequency where waveguide is not used extensively. a.) b.) c.) d.)

3,750 MHz 2,000 MHz 10,300 MHz 150 MHz

236. (ECE Board Problem, April 1999) One of the following central office switching equipment resistance limit refers to the longest subscriber loop length. a.) b.) c.) d.)

1500Ω 300Ω 2000Ω 800Ω

237. (ECE Board Problem, November 1999) A particular area on the surface of the earth where the boresight of a steerable satellite beam is intended to be pointed. a.) b.) c.) d.)

Footprint area Contour boresight area Equivalent service area Effective boresight area

238. (ECE Board Problem, April 1999) Kind of information transfer in digital communication where the bits comprising one character are sent in sequence one at a time. a.) b.) c.) d.)

Parallel transmission Batch transmission Simplex transmission Serial transmission

239. (ECE Board Problem, November 1999) Which of the following antenna where its beamwidth is determine by the dimension of its horn, lens or reflector? a.) b.) c.) d.)

Whip antenna Aperiodic antenna Aperture antenna Long wire antenna

240. (ECE Board Problem, April 1999) In a transoceanic satellite conversation, how much is the typical delay before a reply is heard? a.) b.) c.) d.)

200ms. 900ms. 50ms. 600ms.

241. (ECE Board Problem, November 2000)Position of the maritime ship main antenna, when the radio watch is secured or when the ship is in electrical storm. a.) b.) c.) d.)

AA Main Transmitter Grounded HF

242. (ECE Board Problem, April 1999) Best applies to an optical fiber core. a.) b.) c.) d.)

The same refractive index with the cladding A higher refractive index than the cladding A lower refractive index than the cladding A lower refractive index than air

243. (ECE Board Problem, November 1999) What measure will help you adopt on the antenna system of VHF or UHF mobile transceivers that has very low height antenna? a.) b.) c.) d.)

Increase transmitter to antenna cable Use directional antenna Check grounding system Provide loading coil

244. (ECE Board Problem, April 1999)How do you account the effect of light intensity on the refractive index of a fiber optic? a.) b.) c.) d.)

Decrease Stable Increase Decrease by half

245. (ECE Board Problem, November 1999) Refers to major advantage in the selection of a guided tube. a.) b.) c.) d.)

Durability Low cost Accuracy High power

246. (ECE Board Problem, November 2000) This is the terminal where riser cable pairs are terminated to serve a portion or an entire floor of a building. a.) b.) c.) d.)

Floor terminal distribution area Raceway terminal Floor distribution terminal Riser terminal

247. (ECE Board Problem, November 1999) This referred to a condition in a telephone network where the calling party cannot get connected to the party being called. a.) b.) c.) d.)

Disconnection Open network Blocked call Loss call

248. (ECE Board Problem, April 2000) In data transmission technology, signals such as voice or video are binary transmitted over a cable known as_________. a.) b.) c.) d.)

Video signals Cable signals Baseband signals Audio signals

249. (ECE Board Problem, November 1999) In satellite communications where satellite revolves in an orbit that forms a plane passing through the center of gravity of the erath, this center is called___________. a.) b.) c.) d.)

Geocenter Earth center Plane center Center of gravity

250. (ECE Board Problem, November 1999) In television, the color with the most luminance is ________________. a.) b.) c.) d.)

Blue Green Yellow Red

251. (ECE Board Problem, April 2000) What do you call the dissipated power affecting the antenna efficiency caused by arching effect in high-powered transmitters? a.) b.) c.) d.)

Dissipated power Antenna resistance Corona discharge Antenna loss

252. (ECE Board Problem, November 1999) What is the process in radio communication where information or intelligence signal at a lower frequency is put unto higher radio frequency for transmission to receiving station? a.) b.) c.) d.)

Detection Mixing Modulation Demodulation

253. (ECE Board Problem, April 2000) An inductor that is inserted in an antenna element or transmission line for the purpose of producing a resonant system at specific. a.) b.) c.) d.)

Reflector Traps Loading coil Base loading

254. (ECE Board Problem, November 2000) Satellite orbit around the earth are either, a) all are circular, b) all are elliptical, c) they are either circular or elliptical and d) none of these three. a.) D b.) B

c.) C d.) A 255. (ECE Board Problem, April 2002) What is the main reason why television picture signal uses amplitude modulation, while voice is frequency modulated? a.) b.) c.) d.)

Maintain the power signal at received end. Eliminate attenuation of both video and audio Maintain synchronized scanning between transmit and received video. To minimize interference between signals at received end

256. (ECE Board Problem, April 2002) Which of the following is referred to as a disadvantage of using squelch circuit? a.) b.) c.) d.)

Effect of AGC is reduced for strong signals. Receiver sensitivity is reduced for strong signals. Very weak signals might not be received. Receiver selectivity is reduced for strong signals.

257. (ECE Board Problem, November 2000) How does spatial isolation technique in satellite communications avoid interference? a.) b.) c.) d.)

Use of different polarity antennas. Use of different types of antenna. Employment of highly directional spot-beam Use of low gain antenna

258. (ECE Board Problem, November 2000) A parameter of light beam that do not change quantity when it enters one medium from another. a.) b.) c.) d.)

Intensity Penetration Frequency Wavelength

259. (ECE Board Problem, November 2000) How far is the visual carrier from the aural in the monochrome television broadcast channel have? a.) b.) c.) d.)

1.5 MHz 3 MHz 4.5 MHz 1.25 MHz

260. (ECE Board Problem, November 2000) An order signed by former President F. Ramos last March 1998 providing the national policy in the operation and use of international satellite communication in the Philippines a.) Executive Order 3846

b.) Executive Order 59 c.) Executive Order 456 d.) Executive Order 467 261. (ECE Board Problem, November 2000) Where does the Secretary General in the organizational structure of present ITU report? a.) b.) c.) d.)

WTSG TDAB WRC Council

262. (ECE Board Problem, November 2000) In wire communication system using fiber optic, the packing fraction is related to one of the following statement when referred to fiber optic bundle. a.) Ratio of the total fiber radius, to the sum of the fiber optic bundle radius. b.) Ratio of half of the total fiber radius, to the sum of the fiber optic bundle radius. c.) Ratio of half-sectional area of the fiber optic bundle, to the cross-sectional area of the core d.) Ratio of the total cross-sectional area to the total cross-sectional area of the fiber bundle 263. (ECE Board Problem, April 2000) Determine the local oscillator frequency of a broadcast band receiver using a 455kHz IF and is tuned at 630kHz. a.) b.) c.) d.)

175 kHz 1085 kHz 280 kHz 1530 kHz

264. (ECE Board Problem, April 1999) One of the following is not a probable cause of radiating spurious signal from basic transmitter. a.) b.) c.) d.)

Harmonics Regulated supply Internal heating Parasitic

265. (ECE Board Problem, April 2000) What is the purpose of the two Yagi beam antenna on a VHF TV receiver? a.) b.) c.) d.)

Used to receiver VHF and UHF stations. For receiving low and high band stations. To increase selectivity To increase sensitivity on both hands.

266. (ECE Board Problem, November 2000) What is the noise that is develop in the RF amplifier front end of a TV receiver, which is indicated by a white dot in the picture? a.) b.) c.) d.)

Inter carrier Black Snow IF

267. (ECE Board Problem, April 1999) Region in the atmosphere where ducting occurs? a.) b.) c.) d.)

Ground region Stratosphere Ionosphere Troposphere

268. (ECE Board Problem, April 2000) Who issues an authority to install, operate, and maintain a cable television or render a television service within a specified area in the country? a.) b.) c.) d.)

Department of Transportation and Communication. Board of Communication Congress of the Philippines National Telecommunications Communication

269. (ECE Board Problem, April 1999) What is the source of sidebands in frequency modulation? a.) b.) c.) d.)

Oscillator Baseband Frequency Mixer Carrier Harmonics

270. (ECE Board Problem, November 2000) Which of the very thin layers of the tube’s front surface of the vidicon TV camera located at the middle layer and possess very high resistance when dark, while it reduces greatly when struck by photons of light? a.) b.) c.) d.)

Transparent Conductive Film Photoresistive Layer Photo Inductive Lens Photosensitive Layer

271. (ECE Board Problem, April 2000) One of the following refers to the standard frequency band limits of AM broadcast band? a.) b.) c.) d.)

30-300 MHz 88-108 MHz 3-30 MHz 535-1605 kHz

272. (ECE Board Problem, November 2000)In a cable facilities for a building communications service,________ is referred to as the physical cable within a building or series of buildings which may include both main cable pairs and house cable pairs but not station wiring cable? a.) b.) c.) d.)

Entrance cable Floor distribution cable House cable Building cable

273. (ECE Board Problem, April 1999) What is the range of the lower sideband of an amplitude modulated signal whose carrier is 1.5 MHz and the intelligence component is 50 Hz to 20 kHz? a.) b.) c.) d.)

1.550 MHz to 1.700 MHz 1,499.980 kHz to 2,520.00 kHz 1.48 MHz to 1.4995 MHz 1,500.980 kHz to 2,480.00 kHz

274. (ECE Board Problem, November 2000) A stage in cellular communications where voice channel is assigned to link up a call connection after a mobile or network originated a call. a.) b.) c.) d.)

Call termination Call completion Call connection Call drops

275. (ECE Board Problem, April 1999) How many satellites does not the GPS system consists? a.) b.) c.) d.)

12 satellites 3 satellites 24 satellites 60 satellites

276. (ECE Board Problem, April 2000) Ratio of radiation resistance to the total resistance on an antenna? a.) b.) c.) d.)

Antenna gain Antenna sensitivity Antenna efficiency Antenna ratio

277. (ECE Board Problem, November 2000) What is the frequency of an LED at 1.9eV? a.) 645 GHz b.) 459 GHz

c.) 458 THz d.) 337 THz 278. (ECE Board Problem, April 1999) One of the characteristics of a fiber optic used in order to carry light in several modes of propagation or to become a multimode fiber. a.) Diameter of the core must be equal to the wavelength of the light to be carried. b.) Diameter of the core must be very much greater than the wavelength of the light to be carried. c.) Diameter of the core must be very small compared to the wavelength of light to be carried. d.) Diameter of the core must be much half the wavelength of the light to be carried. 279. (ECE Board Problem, April 2000) One of the following is a communications filter generally used in the transceiver of a single sideband generator. a.) b.) c.) d.)

Low-pass filter Crystal filter Bandpass filter Mechanical filter

280. (ECE Board Problem, April 2000) In computer communications, the term RS-232C is referred to as__________. a.) b.) c.) d.)

Analog connection standard Serial interference standard Digital connection standard Parallel port standard