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COMMUNICATIONS 1. On a telephone system, the loop is open during a. on-hook condition 9 b. off-hook condition c. both a and b d. none of the condition 2. On the subscribers telephone set employing the touch-tone technique, how many signals are transmitted to the telephone exchange for every button that is pressed? a. two VHF signals b. one VHF signals and one

audio-frequency tone c. two audio-frequency tones 9 d. three audible tones 3. How many different tones can a telephone set, employing the touch-tone technique, generate? a. 10 audio frequency tones b. 8 audible tone frequencies 9 c. 4 VHF signals d. none of the preceding choices 4. An Acoustic Coupler is a. a device that radiates audible

signals via a transmitting antenna.

b. a device that converts electric signals into audio signals (and vice versa), enabling to be transmitted over the public telephone network via a conventional telephone handset. 9

c. a device that receives audible signals and retransmits them at VHF frequencies

d. none of the preceding choices 5. Bend loss is a. a form of increased attenuation

caused by bends radiating from the side of the fiber 9

b. an intermittent decrease of transmitter power caused by the curvature of the earths surface

c. a decrease of signal strength at the receiver caused by the bends of a folded dipole in a yaki antenna.

d. none of the preceding choices 6. A voice-grade channel is suitable for transmission of a. VHF signals b. UHF signals c. VHF and UHF signals d. signals with a frequency

ranging from 300 to 3400 Hz 9 7. Insertion loss is a. caused by thermal noise that

intermodulates with the signal traveling on the same medium.

b. a momentary disruption of signal due to power interruption

c. a low level high frequency signal inserted into the original signal caused by thermal noise

d. none of the preceding choices9

8. Erlang is a. a unit of magnetic field density

measured around a conductor b. the number of erroneous bits

received per unit of time c. a unit of electrical energy

radiated in space d. equal to the number of

simultaneous calls originated during a specific hourly period9

9. The local loop of a telephone system is a. a two-wire or four-wire

communication circuit between the customers premise and the central office 9

b. a group of wires connecting a telephone set to a modem

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c. a four-wire circuit connecting a facsimile machine to a computer

d. a single piece of wire connecting the subscribers telephone set to another telephone set in an adjacent room.

10. A communication link is a. a piece of wire that is

connected to ground terminals of all communications equipment in one establishment.

b. a channel or circuit intended to connect other channels or circuits 9

c. a cable connecting a transmitter to the antenna

d. none of the preceding choices 11. A multidrop line is a. a piece of wire with a thick

insulating material that serves to protect the conductive material from damage in the event the wire is dropped.

b. a line designed to withstand high pressure

c. a line or circuit interconnecting several stations 9

d. none of the preceding choices. 12. Echo is a. a signal of the same amplitude

but 180 out of phase from the original signal and mixed with the original signal at the transmitter to produce a more intelligible output signal.

b. a wave which has been reflecting or otherwise returned with sufficient magnitude and delay for it to be perceptible in some manner as a wave distinct from that directly transmitted. 9

c. the signal having a higher frequency than the original and transmitted back to earth by a passive satellite.

d. none of the preceding choices 13. Singing is a. the result of intermodulating

two or more signals of different frequencies to produce a tone having a frequency equal to the sum of the frequencies of the signals intermodulated

b. the result of intermodulating two or more signals of different frequencies to produce a tone having a frequency higher than that of the signal having the highest frequency.

c. an undesired self-sustained oscillation in a system, generally caused by excessive positive feedback 9

d. none of the preceding choices 14. Termination is the a. result of cutting both ends of a

conductor b. result of disconnecting a line

from a transmitter c. all of the preceding choices9 d. none of the preceding choices 15. Telephone signaling provides status information like a. busy tone, dial tone, and

ringing b. congestion and call charge

data c. all of the preceding choices 9 d. none of the preceding choices 16. A two-wire circuit is a. usually in the subscriber loop,

between the telephone set and the local central office. 9

b. a circuit having only two terminals, both terminals having the same instantaneous voltage.

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c. a circuit with one input terminal, one output terminal, and a common ground

d. none of the preceding choices 17. A four-wire circuit is a. used between serving central

offices for long-distance connections, with one pair being used for each direction of transmission 9

b. is a circuit with three output terminals and one input terminal

c. is an oscillator that produces four different frequencies simultaneously

d. none of the preceding choices 18. A leased line is a. a piece of wire used in a local

area network in one building b. a piece of wire connecting a

telephone set to a PABX c. a temporary connection of one

computer to a mainframe via a modem and a telephone line

d. a permanent circuit for private use within a communication network 9

19. PABX stands for a. Private All-purpose

Broadcasting Exchange b. Private Automatic Branch

Exchange 9 c. Public Access Bi-directional

Exchange d. none of the preceding choices 20. A concentrator is a. a system that improves the

signal-to-noise ratio by compressing

b. a device that varies the characteristic of a carrier signal in accordance with the waveform of a modulating signal which contains useful information.

c. a switching system that lets a large number of telephone or data processing subscribers use a lesser number of transmission lines or a narrower bandwidth. 9

d. none of the preceding choices 21. A trunk is a. the base of a communications

tower b. a telephone line connecting

two central offices 9 c. a line connecting one

telephone set to a PABX d. none of the preceding choices 22. In a microwave communications, the frequency range for super high frequency in megahertz is: a. 30 to 300 b. 300 to 3000 c. 3000 to 30000 9 d. 30000 to 300000 23. A simple convenient means of adjusting waveguide power level is provided by what a. slide screw tuner b. slotted line attenuator c. directional coupler attenuator d. flap attenuator 9 24. It is a high gain, low noise level, audio frequency amplifier and a square law calibrated vacuum tube voltmeter used to amplify and measure the output of a crystal and display the information. a. standing wave indicator 9 b. power level indicator c. voltmeter d. pilot indicator 25. It represents energy that has neither been radiated into space not completely transmitted. a. standing waves 9 b. captured waves

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c. incident waves d. modulated waves 26. A microwave communication system space loss expressed in dB is a. 94.2 + 20 log fGHZ +20 log dmiles b. 94.3 + 20 log fGHZ + 20 log dkm c. 92.4 +20 log fGHZ + 20log dkm9 d. 93.5 + 20 log fGHZ +20 log dmiles 27. Given a paraboloid reflector with a diameter D = 6 feet and is operated at 1.5 Ghz. What is the beamwidth between nulls of the reflector, ? a. 8 b. 8.2 c. 7.7 9 d. 7.0 28. Given a paraboloid reflector with a diameter D = 6 feet and is operated at 1.5 GHz. What is the beamwidth between nulls of the reflector, 0? a. 15.3 9 b. 8.2 c. 7.7 d. 7.0 29. Point to point communication between A & B is 90 km (flat terrain). Point A is on top of a hill, 900 ft. above sea level, with a tower height of 23 m. What is the minimum height of the antenna at point B? a. 65 ft b. 73 ft c. 75 ft d. 69 ft 9 30. A microwave communication set up had the following characteristics: Transmitters & receivers antenna gain ------------------------------------- 10 dB line length (transmitter & receiver) ------------------------------------------ 1.25 ft. line loss --------------------- 1.8 dB/100ft transmitter power ------------ 100 W path loss ----------------------- 125 dB modulation --------------------- 100%

Determine the signal level received at the receiver station a. -91 dBw b. -89.5 dBw 9 c. -88.8 dBw d. -90.7 dBw 31. At a distance of 50 km, a 100 watt microwave radio transmitter is used to link to another microwave radio receiver. The received signal level should be equal to negative 80 dBm at the frequency of 6 GHz. Determine the first Fresnel zone radius at mid-point of path. a. 85 ft b. 78 ft c. 82 ft 9 d. 75 ft 32. A waveguide with 4.5 Ghz cut-off frequency is exited with a 6.7 Ghz signal. What is the wavelength in the waveguide. a. 0.196 m b. 0.336 m c. 0.136 m 9 d. 0.236 m 33. A rectangular waveguide has dimensions of 3 cm x 5 cm. What is the TE10 mode cut-off frequency? a. 2 GHz b. 3 GHz 9 c. 2.5 GHz d. 3.5 GHz 34. What is the power density in W/m2 at a distance of 1 km from a 1000W isotropic source? a. 7.58 x 10-5 b. 7.95 x 10-5 9 c. 7.85 x 10-5 d. 7.59 x 10-5 35. A microwave antenna with a length of 6 cm radiation a 12 cm wavelength signal. Calculate the mean field distance

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a. 6.1 cm b. 6.0 cm 9 c. 6.2 cm d. 5.0 cm 36. A tapered termination of a length of waveguide that provides the impedance transformation between waveguide impedance and free space impedance. a. isotropic radiator b. horn radiator 9 c. dipole d. parabolic reflector 37. Transmission lines which can convey electromagnetic waves only in higher order modes are usually called a. coaxial cable b. twisted pair of telephone wire c. power lines d. waveguides 9 38. Refers to the ratio of an electric field component to a magnetic field component at the same point of the wave a. characteristic impedance b. wave impedance 9 c. load impedance d. intrinsic impedance 39. Refers to the ratio of the phasor fields E and H for a plane (TEM) wave in an unbounded medium a. wave impedance b. load impedance c. intrinsic impedance9 d. characteristic impedance 40. Defined as the quotient of the maximum radiation intensity over the average radiation intensity a. aperture gain b. directivity gain 9 c. transmission gain d. power gain

41. Find the forward tilt angle t for a vertically polarized 3 Ghz wave traveling in air along the surface of a smooth freshwater lake. a. 6.0 b. 6.2 c. 6.4 9 d. 6.8 42. Another term for Amplitude Modulation (AM) is: a. Double Sideband Full Carrier

(DSBFC) 9 b. Single Sideband Suppressed

Carrier (SSBSC) c. Frequency Modulation (FM) d. Pulse Code Modulation (PCM) 43. A pulse amplitude modulator uses a modulating signal whose frequency is 3 kHz maximum. The practical sampling frequency is: a. 6 kHz 9 b. 7.25 kHz c. 2.5 kHz d. 3 kHz 44. If a television channel starts at 66 MHz, the sound carrier is found at: a. 4.5 MHz b. 67 MHz c. 55.25 MHz d. 71.75 MHz 9 45. A two-channel Time Division Multiplexer with channel 1 having the highest frequency of 3 kHz while channel 2 has only 1 kHz. The lowest commutating or sampling frequency is: a. 18 kHz 9 b. 15.5 kHz c. 6 kHz d. 24.75 kHz 46. The main purpose of the 19 kHz pilot in a stereo multiplexed signal in FM is for the receiver to: a. Indicate stereo reception b. Demodulate 9

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c. Modulate d. Over Modulate 47. A Pulse code modulator (PCM) uses an eight-bit quantizer. If the quantizer output has FF(Hex) and 00(Hex) which represents a quantized voltage of 1 volt and 0 volt respectively, then A6(Hex) represents what: a. 6 volts b. 0.25 volts c. 0.1 volts d. 0.65 volts 9 48. Type of operation performed at the transmitter to achieve efficient and reliable information transmission. a. Transmission b. Filtering c. Modulation 9 d. Multiplexing 49. Another name for multiplier circuit a. Balance Modulator 9 b. Discriminator c. Clipper d. Integrator 50. 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 b. Frequency Division

Multiplexing c. Quadrature Multiplexing 9 d. Duplexing 51. A good example of a pilot tone system used in commercial frequency modulation stations. a. Frequency Modulation b. Frequency Division

Multiplexing c. Time Division Multiplexing d. Stereo Multiplexing 9

52. Range of carrier frequencies for commercial FM broadcasting a. 535 kHz 1605 kHz b. 88 GHz 108 GHz c. 88 MHz 108 MHz d. 0.88 kHz 1.08 kHz 9 53. They are subcarriers that are arranged so that the channels occupying adjacent frequency bands with some frequency space between them is known as: a. Guard Bands 9 b. AM Bands c. Band Gap d. Band Diagram 54. The amplitude of a train of constant-width pulses is varied in proportion to the sample values of the modulating signal a. Phase Modulation b. Frequency Shift Keying c. Amplitude Shift Keying d. Pulse Amplitude Modulation 9 55. Determine the bandwidth of an AM transmitter if the carrier frequency is 1000 Khz and the modulating frequency varies from 1 kHz to 10 Khz. a. 2000 Hz b. 2 kHz c. 20 kHz 9 d. 20.1 kHz 56. The information of an AM signal resides in the a. Upper Sideband only b. Lower Sideband only c. Upper & Lower Sideband

Only9 d. Carrier signal 57. The transmission and reception of information is called: a. Modulation b. Communication 9 c. Radiation d. Emission

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58. The process of varying some characteristic of a high frequency sine wave in accordance with the variation of the modulating signal is called: a. Communication b. Propagation c. Restoration d. Modulation 9 59. A 10 Mhz carrier is amplitude modulated by a 100 Khz signal. What frequency components are present in the output wave? a. 10 MHz and 100 kHz b. 10 MHz, 10.1 MHz and 100 kHz c. 10 MHz, 10.1 MHz and 9.9 MHz 9 d. 10 MHz, 9.9 MHz and 9.8 MHz 60. Any unwanted form of energy interfering the reception of wanted signal is called: a. Sidebands b. Frequency spectra c. Noise 9 d. Modulation 61. The instantaneous frequency of the carrier signal is switched between two (or more) values in response to PCM code. a. phase shift keying b. frequency shift keying 9 c. frequency modulation d. amplitude shift keying 62. Digital Signals a. can provide a continuous set of

values b. represent values as discrete

steps 9 c. cant utilize decimal or binary

systems d. none of the above 63. If you are going to receive a message, for example FRIDAY, you could guess that the letter after FRIDA was Y because spoken language is a. Redundant 9

b. Has high information content c. Inflexible d. Both a and b 64. When are bits per second and bands equivalent? a. Never b. When the transmission line

changes state each time a bit changes 9

c. When a telephone modem feeds your personal computer

d. always 65. If the maximum signaling speed on a certain DC cable is 2000 bps, and we are presently passing data at 600 bps, what effect would doubling the cable length have an our ability to communicate? a. No effect b. The maximum speed would

fall, but we would not be affected because we are operating below the maximum speed

c. Lengthening the cable would reduce the maximum speed to below 600 bps, and we could no longer communicate 9

d. The maximum speed would rise to 4000 bpd.

66. Spacing bias distortion results in: a. Space being lengthened and

marks being shortened 9 b. Space being shortened and

marks being lengthened c. Space being lengthened but

marks being unaffected d. Extra spaces being printed on

the teletypewriter 67. An AC transmission path has the characteristics of a. A low-pass filter b. A high-pass filter c. A band-pass filter 9 d. Both a and b

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68. The data transmission rate of a modem is measured in a. bytes per second b. baud rate 9 c. bits per second d. megahertz 69. Which is not an example of data communications? a. A teletype printing news

bulletins b. A computer transmitting files to

another computer c. An automatic teller machine

checking account balances with the banks computer

d. a salesman telephoning orders to the office 9

70. Two-state (binary) communications system are better because: a. They can interface directly with

the analog telephone networks b. The components are simpler,

less costly and more reliable 9 c. People think better in binary d. Interstate calls are less costly 71. Switching systems a. improve the efficiency of data

transfer 9 b. are not used in data systems c. require additional lines d. are limited to small data

networks 72. What are the effects of transmission line loading at AC? a. Attenuation is decreased, and

signaling speed is raised b. Attenuation is increased, and

signaling speed is decreased c. Attenuation is decreased at

some frequencies and raised at others 9

d. You cant tell without more information

73. Which of the following is not an important cause of distortion in DC signaling? a. Line capacitance b. Line Inductance 9 c. Detector hysteresis d. Line resistance 74. The telephone is attractive for transmitting digital data because a. Telephone calls casts are

decreasing with more modem equipment

b. There is no basic difference between the problems faced by a voice signals and those faced by digital signals

c. Digital and human speech share many signal characteristics

d. Telephones are standardized and easy to find 9

75. Which of the statement is true? a. Parallel data transmission is

more complex than serial transmission

b. Serial data transmission is slower than parallel transmission, given the same pulse width in each case

c. A transmission line will operate faster with parallel data than it will with serial data. 9

d. Serial transmission is suited to use over single pair of wire

76. Knowing the bandwidth of circuit, you can draw a meaningful conclusion about many characteristics of the circuit. Which of the following do you not know about from knowing the bandwidth? a. Maximum information capacity b. Maximum signaling speed c. Operating frequency 9 d. You can tell about all of these if

you know bandwidth

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77. You are presently passing baseband data at 4800 bps over a one-mile cable. Based on Kelvins Law, what would you expect to be a reasonable speed for data transmission if you lengthened the cable to four miles? a. 2400 bps b. 1200 bps c. 600 bps d. 300 bps 9 78. The correctness and accuracy of the transmitted message content is: a. Verified by the modem b. Determined by the sender and

receiver, not by the communication system 9

c. Ensured by used of digital techniques

d. Depends on how long the signals take to arrive at the receiver

79. What is the function of regenerative repeaters? a. To eliminate bias distortion b. To help with loading of the

telegraph lines c. To reshape the pulses after

they have become distorted 9 d. To reduced required signal

levels 80. Extended ASCII a. Adds extra digits to standard

ASCII 9 b. Provides 128 additional

character definitions beyond standard ASCII

c. Doubles the bit length of each ASCII character

d. Provides extra characters that you define

81. The Baudot code a. was invented by the Baudot

brothers, Mark and Space b. requires the escape characters

to print numbers

c. requires shift characters to provide sufficient combinations9

d. was invented by Emiles sister, Bridgette

82. The difference between timing and framing is: a. timing is concerned with the

individuals bits; framing is concerned with the boundaries between characters 9

b. timing refer to serial transmission; framing refers to parallel

c. timing is concerned primarily with a synchronous systems; framing is concerned with synchronous systems

d. none of the preceding choices 83. ASCII terminals are generally defined as: a. Terminals using synchronous

transmission in EBCDIC b. Terminals using synchronous

transmission in ASCCI c. Terminals using a synchronous

transmission in ASCII 9 d. any terminal having an

American (dollar sign) keyboard

84. Teleprinters a. Are only for printing at remote

locations not for input b. After both high speed operation

and a variety of formatting controls

c. Have a printer for output and may have a keyboard for input9

d. Both a and b 85. Reperforators: a. A device for punching paper

tape off-line b. A printer that ahs no keyboard

and the only and print the message on paper

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c. A device that punches paper tape from signal received over the communication line 9

d. A device that reads transmit punched paper tape

86. Impact printers: a. Strike a ribbon against the

paper to produce character image

b. Include ink-jet and terminal devices

c. A receiver-only-printer with a keyboard 9

d. are rapidly becoming absolute 87. Serial printers a. Are used to transmit grains

prices b. Are faster than CRT terminals

and offer more flexibility c. Print one character at a time 9 d. Usually used serial interfaces 88. Which of the following is not common to punched card and magnetic media terminals? a. Both are used to facilitate

transmission of computer data without having to change the medium in which it is stored

b. Both were developed before the teletypewriter

c. Both use the same data transmission principles as the teletypewriter and the telegraph 9

d. both transmit data at higher speeds than teletypewriters

89. CRT terminals: a. Are most widely used hardcopy

terminals b. Offer high-speed display and

formatting flexibility 9 c. Do not normally utilize

microprocessor d. Are strictly typewriter-style

90. The principal difference between batch processing and on-line processing is: a. Computer resources are used

more efficiently for on-line processing

b. Teleprinters are used for batch processing; CRTs are used for on- line processing

c. Transactions are grouped for batch processing; transactions are processed as need for on-line processing. 9

d. none of the preceding choices 91. Which of the following statements about the ASCII code is not true? a. ASCII is an ANSI standard b. ASCII is a BCD code 9 c. ASCII can be represented

using 8 bits d. ASCII and CCITT Alphabet No.

5 are nearly identical 92. What is the Hamming distance between the characters 1001101 and 1011011? a. 0 b. 1 c. 2 d. 3 9 93. Which of the statement is not true? Convolutional codes: a. Depend on both current

characters to be encoded and those that have been encoded previously

b. Are also called recurrent codes c. Are used with forward error

corrections d. Are a form of block code 9 94. What type of CRT-based terminals most closely resembles the KSR teletypewriter configuration? a. Buffered terminal b. Dumb terminal 9 c. Smart terminal d. Bus terminal

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95. Which of the following is not generally used as a stand-alone data communications terminals? a. a microcomputer b. Magnetic media transceivers c. Mainframe computers 9 d. Minicomputers 96. One of the following standards organizations produce standards which are not generally used in the U.S. which one is it? a. CCITT 9 b. ISO c. ANSI d. UL 97. The difference between synchronous and asynchronous data transmission can be observed by noting what? a. How fast the data is

transmitted on the circuit b. When stop and star pulses are

used9 c. How accurate the clock is d. All of the preceding 98. Some characteristics of the EBCDIC code are: a. It is used exclusively on IBM

computers b. It is binary coded decimal code

expanded to allow the transmission of letters and control characters9

c. EBCDIC can easily be transformed into ASCII- 8 by adding hexadecimal constant to the ASCII- 8 code

d. all of the preceding 99. One of the following techniques will not help to correct for transmission line errors. Which is it? a. N-of-M codes b. Checksums c. Algorithmic conversions 9 d. Parity checking

100. What is the primary considerations when designing an error control system for data communications? a. How many errors the system

will detect and correct b. The overall function and needs

of the networks 9 c. The efficiency of the code that

results from the design d. All of the preceding 101. Which of the statement is not true? a. Checksums detect errors more

effectively than checking b. Cyclic Redundancy checking

can find all of certain c. Parity checking is capable of

providing enough information to detect and corrects errors

d. A Hamming code of distance 5 can detect and correct 4 errors in transmission 9

102. Pulse Amplitude Modulation is: a. Similar to amplitude modulation

in the analog world 9 b. Used in radio communication c. Relatively insensitive to noise

distortion d. Aversion of frequency

modulation 103. Pulse Duration Modulation a. Is similar to FM b. Is difficult to detect

accurately9 c. Is not widely used d. Is vulnerable to noise 104. Fourier Analysis a. Is merely a mathematical

exercise b. Tells us how to build a pulls

train c. Provides insight on another

way of looking at a pulse train9

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d. Has no application in data communications

105. What is the easiest type of system to use for secure (encrypted) computer communications? a. Frequency Division

Multiplexing b. Pulse Code Modulation 9 c. Pulse Duration Modulation d. Pulse Position Modulation 106. Multiplexing a. Has been in use since the

1920s b. Involves separating signals into

pieces that dont interfere with anything else

c. Expands telephone plant capability

d. Separates signals in space, frequency, or time 9

107. Which of the following is not a commonly used modern modulation method? a. 8-FSK 9 b. BPSK c. 4-PSK d. 8-QAM 108. Why is it necessary to use carrier in data communications? a. Because it makes modulation

easier b. Because data signals cannot

be transmitted to their destination without the aid of a carrier 9

c. Because multiplexing systems need carriers to function properly

d. All of the preceding 109. What is the relationship between power level, bandwidth, and modulation index of a frequency modulated signal?

a. As modulation index increases, bandwidth and power increases

b. As modulation index increases, bandwidth and power increases

c. As modulation index increases, bandwidth increases and power decreases 9

d. As modulation index increases, bandwidth decreases and power increases

110. Given a signal which ranges in frequency from 100Hz to 10KHz, and 256 quantizing levels, what is the minimum pulse rate required to transmit this signal? Ignore framing pulses a. 10, 000 bps b. 20, 000 bps c. 140, 000 bps d. 160, 000 bps 9 111. The standard first-level digital multiplex system in the U.S. operates at: a. 2.048 Mbps b. 44.736 Mbps c. 1.544 Mbps 9 d. 9, 600 bps 112. The area of coverage of a satellite radio beam is called its: a. Beamwidth b. Circular polarization c. Footprint 9 d. Identity 113. Fiber optic cables operate at frequencies near: a. 20 MHz b. 200 MHz c. 2 GHz d. 800 THz 9 114. Since the optical fibers carry light rays, the frequent y of operation is that of light. The transmission

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wavelength used for current single-mode fibers is: a. 1.2 micrometers 9 b. 1.5 micrometers c. 3.0 micrometers d. 4.0 micrometers 115. Which of the following statements about time-division multiplexing is not true? a. TDM is becoming less widely

used as PCM systems are introduced 9

b. TDM is ideal for data communications because the data are already in digital form

c. TDM can use any of several modulation schemes

d. TDM will probably coexist with PDM for many years

116. Modems are used to connect data equipment to communications lines. Which of the following statements about modems is not true? a. Modems operate at 300, 1200,

or 4800 bits per second b. Acoustics-coupled modems are

not useful when an operator is in attendance 9

c. Some modems can operate without being connected to a computer, and transfer data to and from the computer off-line

d. none of the preceding 117. Which of the following is an example of space-division multiplexing? a. Receiving television shows on

different channels b. The distribution in our

automobile c. Telephone wires on the

poles9 d. all of the preceding 118. PDM maybe generated a. by differentiating pulse-position

modulation

b. with a monostable multivibrator9

c. by integrating the signal d. with a free-running

multivibrator 119. Which of the following is not a characteristic of pulse code modulations? a. Applicable to any signal

waveform b. Easily implemented in

hardware, and becoming widely used worldwide

c. Minimize the effect of noise during transmission and provides for coding to remove noise in the signal 9

d. does not actually transmit the signal impressed on the modulator

120. Which statements below is not true? a. Pulse code modulation makes

it possible to make transmission line noise effects arbitrarily low

b. PSK is often used in preference to FSK because it makes more efficient use of bandwidth

c. 8-PSK outperforms 8-QAM for transmitting data efficiently 9

d. Nyquists Sampling Theorem defines the parameters on which pulse code modulation is based

121. Why establish the 4-KHz channel as the basic building block of multiplex systems? a. Because multiples of four make

designing the equipment easier b. Because supergroups and

mastergroups are easier to form based on an even multiple9

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c. Because it represents the width of a voice channel and its guard bands

d. none of the preceding 122. Direct machine-to-machine transmission over long distance without modems is not practical because: a. Copper wire does not transmit

DC efficiently b. A DC path that will handle data

in pulse form does not exist 9 c. Data comes from the computer

in the form of tones, not pulses d. none of the preceding 123. RS 232, RS 530, V.24, and V.21 are examples of: a. Standards for various types of

transmission channels b. Standards for interfaces

between terminals and modems 9

c. Standards for end-to-end performance of data communication systems

d. none of the preceding 124. A smart modem can: a. Detect transmission errors and

correct them automatically b. Correctly answer multiple-

choice quizzes c. Accept commands from the

terminal via the RS 232 interface 9

d. none of the preceding choices 125. RTS/CTS: a. Is the way of the DTE indicates

that it is ready to transmit data, and the way the DCE indicates that it is ready to accept data9

b. Is the way the modem indicates ringing, and the way the terminals indicates it is ready for the call to be answered

c. Are the pins that represent received transmission and carrier transmission

d. none of the preceding choices 126. The CCITT V.26 has a modulation rate of: a. 1200 Hz b. 1200 bauds 9 c. 1560 cps d. 2000 bauds 127. Synchronous modems cost more than asynchronous modems because: a. They are larger b. They must operate on a larger

beamwidth c. The production volume is

larger d. They must contain clock

recovery circuits 9 128. The digital-to-analog converts in a synchronous modem send signals to the: a. Modulator b. Transmission lines c. Terminal d. Equalizer 9 129. Multiplexing is: a. The process of increasing

bandwidth on a channel b. A technique that enables more

than one data source to share the use of a common line 9

c. Mailing letter at the post office d. The ability to share frequency

by time 130. Demultiplexing by a time division multiplexer occurs based upon: a. The position of data within a

time 9 b. The position of frame within a

group of frames c. The activity of a connected

device

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d. The priority assigned to a connected device

131. The PCM sampling rate is 8000 samples per second because: a. The represents the maximum

rate technology supports b. This rate allows unique values c. This rate allows the faithful

reconstruction of an analog signal 9

d. This rate is easily produced by a sampling chip

132. Message switching, as compared to circuit switching, does not offer which of the following: a. Lower costs to users b. Greater link efficiency c. Improved timeliness of

message handling 9 d. Precedence handling of

messages 133. Typical LANs support busses of: a. 500 feet b. 1000 feet 9 c. 5000 feet d. 10000 feet 134. Which of the following is not a dedicated or circuit-switched network? a. Point-to-point teletype circuit b. Torn-tape teletype 9 c. Multipoint data terminal system d. all of the preceding 135. Based upon experienced gained from ARPANET, which of the following application is suitable for packet switching? a. Industrial process control b. Military quick-response

command and control 9 c. Electronic mail d. Remote terminal access to

mainframe programs

136. Which of the following is not a characteristic of packet-switched networks? a. Low cost to establish b. Dynamic allocation of

Bandwidth c. Packet-by-packet routing

decisions made by IMOs 9 d. Sophisticated control software 137. Local area networks draw heavily on the technology of: a. Circuit switching 9 b. Message switching c. Telephone switching d. Packet switching 138. Which of the following pieces of information would you not expect to find in a packet header? a. Message segment 9 b. Packet number c. Error-number d. Routing information 139. What is the major drawback to local area networks at the present time? a. Lack of standards 9 b. Not enough vendors c. Cost of the interconnecting

cable d. Software problems 140. Which of the following is to a message switched system? a. AUTODIN b. ARPANET c. SAGE 9 d. Telex 141. If each character in an XMODEM block has an ASCII value of 50 what would be the value of the check sum added to the block? a. 50 b. 23 c. 41 d. 25 9

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142. In the XMODEM protocol, the sender waits for what character from the receiver before beginning transmission? a. WACK b. ACK c. RVI d. NAK 9 143. 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 of the electric-

wave plane 9 c. the horizontal or vertical plane

of the electric wave d. the direction in which the

magnetic wave is radiated 144. Direct waves of very high frequency a. are refracted less than direct

waves of low frequency b. lag behind earth-reflected

waves c. are affected by changes in

density 9 d. have a transmission range that

can be extended greatly 145. The distance from the transmitting antenna to the point where direct waves strikes the earth is called: a. radio horizon 9 b. optical horizon c. geometric horizon d. the line of sight 146. The D, E, and F layers are called: a. Mark Space layers b. Davidson Miller layers c. Kennelly Heaviside layers 9 d. Maxwell layers 147. The critical frequency of the vertically transmitted radio wave is higher

a. in summer than in winter b. in nighttime than in daytime c. for high frequencies than for

low frequencies d. in times of a very low sunspot

activity than in times of very high sunspot activity

148. For a two-wire line, Z0 is higher when: a. the D:d ratio is smaller b. the wire size is larger with

respect to the spacing of the conductors

c. the spacing is varied in accordance with the frequency

d. the wire size is small with respect to the spacing of the conductors 9

149. In practice, the transmission lines are almost connected to antennas that have a: a. resistive load at the resonant

frequency 9 b. resistive load whose resistance

is greater than the characteristics impedance of the line

c. resistive load whose resistance is less than characteristics impedance of the line

d. capacitive load 150. Typed transmission lines: a. should be used in applications

in which the transmission line is more than a wavelength long

b. are usually connected to the voltage feed point or to the current feed point 9

c. should be designed so that corresponding points on the conductors have opposing fields of unequal magnitude

d. can not be converted into untuned lines

151. The magnetic and electric fields:

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a. reach their greatest points at the same moment

b. occur 90 out of phase 9 c. occur 180 out of phase d. occur 270 out of phase 152. The three components of the magnetic fields are in phase: a. in space with the components

of the electric field b. in time 9 c. four times each cycle d. two times each cycle 153. A transmission line with a characteristics impedance of 450 is terminated in a purely resistive load. It is found by measurement that the minimum value of voltage upon it is 7.5V, and the maximum is 9V. What is the value of load resistance? a. 200 or 450 b. 325 or 500 c. 375 or 540 9 d. 250 or 500 154. A (75 j50) ohm load is to be matched to a 75-ohm line to give SWR = 1. What is the characteristics impedance of the quarter-wave transformer, connected directly to the load? a. 90 ohms 9 b. 100 ohms c. 110 ohms d. 120 ohms 155. To couple a coaxial line to a parallel-wire, it is best to use a: a. directional coupler b. quarter-wave transformer c. balun 9 d. slotted line 156. The velocity factor of a transformer line: a. is higher for a solid dielectric

than for air b. is governed by the skin effect

c. depends on the dielectric constant of the materials used9

d. increases the velocity along the transmission line

157. For transmission-line load matching over a range of frequencies, it is best to use a: a. broadband directional coupler b. balun c. single stub of adjustable

position d. double stub 9 158. Skin effects refers to what? a. The problems associated with

the insulators, or skin, of a cable

b. The tendency of AC to flow near the outer surface of a conductor 9

c. The tingling feeling in your skin when you are near high-frequency transmitters

d. none of the preceding choices 159. Why is open-wire line still found in many telephone system application? a. Because data signals travel

better on open-wire line b. Because it is not economically

sensible to replace it 9 c. Because multiplexing systems

need the bandwidth provided by openwire

d. all of the preceding 160. Which of the following statements about flat unpaired cable is not correct? a. flat cable has a good adjacent

pair noise immunity 9 b. flat cable has poor immunity to

noise induced by sources outside the cable

c. flat cable is widely used in data applications

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d. flat cable is effective in crumpled locations where round cable will not easily fit

161. What is the relationship between possible bandwidth and signal frequency? a. As bandwidth decreases,

signal frequency decreases b. As signal frequency increases,

bandwidth increases 9 c. As signal frequency increases,

bandwidth decreases d. They are not related 162. One of the following transmission impairments is not a problem with a microwave transmission. Which not? a. Multipath fading b. Ducted signals c. Rain attenuation 9 d. all of the preceding 163. What type of cable would you choose if you wanted an inexpensive, longdistance, medium-bandwidth transmission link where several circuits ran in parallel? a. Open wire b. Quaded-exchange cable c. Quadded-toll cable 9 d. Coaxial cable 164. One of the following is not an advantage of coaxial cable for data communications, which is it? a. Wide bandwidth b. Flexibility of the system layout c. Noise immunity d. Right-of-way costs 9 165. Which of the following is not a characteristic of satellite transmission systems? a. Long signal delays from sender

to receiver 9 b. Affected by weather in the

earths surface

c. Vulnerable to the right galactic noise levels of space

d. Require demand assignment schemes to achieve best use

166. You are told that certain satellite uses transmissions in the 4/6 GHz band. What does that mean? a. The satellite transmits to earth

at 4 GHz, the earth station to the satellite at 6 GHz

b. The earth station transmits at 4 GHz, the satellite transmits to earths at 6 GHz

c. The satellite transmits to earth in the frequency band lying near 4 GHz, and the earth station transmits to the satellite in the band lying near 6 GHz 9

d. none of the preceding 167. Which of the following system is least affect by variations in the refractive index of the layers of the earths atmosphere? a. Microwave line of sight

systems b. High frequency radio c. Satellite systems 9 d. UHF radio systems 168. What is the capacitance of 55 miles No. 4 copper wire spaced 18 inches? From wire tables, we find that No. 4 copper has radius of 0.10215 in. a. 0.476 F 9 b. 0.086 F c. 0.86 F d. 0.476 F 169. 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 9 d. reduces the load current

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170. If measurements are taken along transmission line with an oscilloscope when there are no standing waves, the pattern would appear as: a. surge impedance times current b. high voltage peak c. impedance squared d. a sinusoidal waveshape 9 171. A characteristics of an infinite transmission line is that: a. the impedance in equals the

impedance out 9 b. it carries waves at the velocity

of light c. it can be connected to

mismatched loads d. the impedance varies with the

length of the line 172. A quarter-wave transmission line shorted at the end: a. has a minimum current at the

shorted end b. has the characteristics of a

parallel-tuned circuit 9 c. has the characteristics of a

series-tuned circuit d. reflects a low impedance to the

supply 173. The outer conductor of a coaxial transmission line is usually grounded at the: a. input and output 9 b. output only c. input only d. point of higher SWR 174. A certain feed line has a high SWR. It can be caused by: a. an impedance mismatch 9 b. use of non-resonant c. matching the load to the line d. excessive transmitter output 175. Why is nitrogen used in coaxial cables or waveguides?

a. To increase the electrostatic capacitance

b. To keep it dry 9 c. To prevent it from collapsing d. To lower the voltage 176. Waveguide is a. a device used to determine the

wavelength of a signal b. a braided copper wire used for

transmission of high frequencies

c. a plastic tubular transmission line for high RF network

d. a hollow metal tube used for transmission of high frequencies 9

177. How can you couple into and out of a waveguide? a. Wrap a coil of wire around one

end of the waveguide b. Use a piece of wire for coupling

in and out 9 c. Use a resonant tank feeding

slot in waveguide d. Force electrons through the

wall of the waveguide 178. What is the noise level at the output of the amplifier shown, if the noise power is given by 10-5 W? a. 80 dBrn b. 90 dBrn 9 c. 100 dBrn d. none of the preceding 179. For some application, circular waveguides maybe preferred to rectangular ones because of: a. lower attenuation 9 b. rotation of polarization c. the smaller cross-section

needed at any frequency d. freedom from spurious modes 180. In order to reduce cross-sectional dimensions, the waveguide to use is:

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a. circular b. rigid 9 c. rectangular d. flexible 181. The main difference between the operation of transmission lines and waveguides is that: a. Waveguides are not

distributed, like transmission lines

b. Transmission lines can use stubs and quarter wave transformer, unlike the waveguide

c. Transmission lines use the principal mode of propagation, and therefore do not suffer from low-frequency cut-off 9

d. Terms such as impedance matching and standing-wave ratio cannot be applied to waveguide

182. What is the optimum length of a Marconi antenna for the transmission of a 300 MHz signal? The antenna velocity factor is 0.85. a. 0.21 m 9 b. 0.22 m c. 0.23 m d. 0.24 m 183. An ____ is defined as a volume control for specific frequency ranges. a. volume control b. AGC c. Equalizer 9 d. tone controls 184. ______ are usually of the two knots type (one for bass and one for treble). a. volume control b. tone controls 9 c. AGC d. tuning knob

185. ______ is the microphone characteristics that results in a boost in bass frequencies for close microphone spacing a. Field effect b. P.A. effect c. Proximity effect 9 d. Reverberation 186. The audio frequency range is: a. 20 kHz to 20 MHz b. 3 Hz to 20 kHz c. 300 Hz to 3 kHz d. 0 Hz to 4 kHz e. 20 Hz to 20 kHz 9 187. The bass frequency range is a. 20 Hz to 40 Hz b. 1 Hz to 20 Hz c. 40 Hz to 160 Hz 9 d. 10 Hz to 20 Hz 188. The high frequency range of audio signals is a. 2, 500 Hz to 5, 000 Hz b. 5, 000 Hz to 10 kHz 9 c. 10 kHz to 20 kHz d. 20, 000 Hz to 30 kHz 189. The SPL in dB of a voice paging in an office is a. 90 b. 65 9 c. 55 60 d. 80 85 190. The SPL in db of an auditorium with contemporary music is a. 80 b. 85 90 c. 95 100 9 d. 100 105 191. The church in SPL in dB with speech reinforcement only is a. 90 b. 80 85 9 c. 85 90 d. 90 95

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192. Intensity can also be called as a. volume b. loudness 9 c. sharpness d. bass and treble 193. The loudness of a sound depends upon the energy of motion imparted to the ____ molecules of the medium transmitting the sound. a. loudness b. volume c. moving d. vibrating 9 194. _____ is affected by the distance between the listener and the source of the sound and its intensity varies inversely with the square of this distance a. volume b. bass c. treble d. loudness 9 195. If the distance between the listener and the source of the sound is doubled, the intensity is reduced to a. 1/2 b. 1/3 c. 2/3 d. 9 196. If the distance between the listener and the source of the sound is decreased to 1/2 the original amount, the intensity of the sound would be ___. a. 2 times as great b. 3 times as great c. 4 times as great 9 d. 5 times as great 197. The frequency range of a piano is from 25 to 8, 000 Hz. What is the range of wavelengths in feet? a. 45.2 ft to 0.14125 ft 9 b. 142.3 ft to 163.8 ft c. 0.14125 ft to 45.2 ft

d. 300 ft to 3, 000 ft 198. If the sound waves are converted to electrical waves by a microphone. What is the frequency of the electric current? a. 3 to 30 MHz b. 25 to 8, 000 Hz 9 c. 4 to 40 Hz d. 30 to 3, 000 Hz 199. For a music lover concert A is 440 Hz. If a musical note one octave higher were played, it would be ____ that frequency. a. one-half b. one-fourth c. double 9 d. triple 200. In a 220 Hz, if a note were played one octave below it would be _____. a. 22 Hz b. 27.5 Hz c. 440 Hz d. 110 Hz 9 201. Much of music is generally referred to in a. harmonics b. good hearing c. fidelity d. octaves 9 202. ______ is a undesired change in wave form as the signal passes through a device. a. noise b. vibration c. distortion 9 d. harmonics 203. Distortion enhances intelligibility when an ____ is added. a. equalizer b. igniter c. exciter 9 d. emulsifier

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204. A class of signal processors are known as a. amplifiers b. equalizers c. microprocessors d. exciters 9 205. Hall construction and internal finishes affect the final sound quality a. poorly b. mildly c. significantly 9 d. badly 206. Positioning a loudspeaker near a wall can dramatically alter its frequency response in two distinct ways namely a. gump and dump b. hump and notch 9 c. fade and gone d. bad and worst 207. The acoustics of most auditoria are very ____ when the room is full compared to the empty condition a. different 9 b. similar c. good d. bad 208. A ____ converts acoustical energy to electrical energy a. electro-acoustic b. microphone transducer 9 c. microphone d. electric microphone 209. All microphone have two basic component namely, _____. a. wired and body b. ceramic and crystal c. diaphragm and generating

element 9 d. coil and magnet 210. The kinds of generating elements are ____.

a. expense and fidelity b. complexity and ruggedness c. longevity d. all of the preceding 9 211. At 20C sound travels at 1130 ft./sec. for two loudspeakers separated by 1 ft, calculate the notch frequencies which will cause signal misalignments? a. 130 Hz, 230 Hz b. 130 to 390 Hz c. 1130, 2260, 3390 Hz 9 d. 130, 230, 460, 920 Hz 212. At room temperature, calculate the velocity of sound in meters/sec? a. 348.3 m/s b. 132 m/s c. 980 m/s d. 348.03 m/s 9 213. Calculate the velocity of sound in ft./sec. if the temperature is 300F? a. 132 ft/sec b. 1320 ft/sec c. 1350.303 ft/sec 9 d. 1920.435 ft/sec 214. Atmospheric noise becomes less severe at frequencies a. Above 30 MHz 9 b. Below 30 MHz c. Above 3000 KHz d. Below 3000 KHz 215. Indicate the noise whose source is in category different from that of the other three? a. Solar noise b. Cosmic noise c. Atmospheric noise 9 d. Galantic noise 216. Indicate the false statement a. Industrial Noise is usually of

the impulse type

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b. Static is called by lightning discharges in thunderstorms and other natural electric disturbances occurring in the atmosphere

c. Distant stars have another source of man-made noise 9

d. Fluorescent lights are another source of man-noise

217. Which of the following is not a source of industrial noise? a. Automobile ignition b. Sun 9 c. Electric motors d. Leakage from high voltage line 218. One of the following types of noise becomes of great importance at high, frequencies is the a. Shot noise b. Random noise c. Impulse noise d. Transit-time noise 9 219. Indicate the false statement a. The noise generated in a

resistance or the resistive component of any impedance is random

b. Random noise power is proportional to the bandwidth over which it is measured

c. A random voltage across the resistor does not exist 9

d. All formula referring to the random noise are applicable only to the value of such noise

220. The value of the resistor creating thermal noise is doubled. The noise power generated is therefore. a. Halved b. Quadrupled c. Doubled d. Unchanged 9

221. Indicate the false statement: a. HF mixers are generally noisier then HF Amplifiers b. Impulse noise voltage is

dependent of bandwidth9 c. Thermal noise is independent

of the frequency at which is measured

d. Industrial noise is usually of the impulse type

222. The total space loss of transmission and reception for two ground stations with uplink frequency of 8 GHz and a downlink of 6 GHz with angle of elevation of 3 A and 7 A respectively is: a. 403 dB 9 b. 100 dB c. 20 dB d. 215 dB 223. The maximum propagation delay of a geostationary satellite is: a. 278 ms 9 b. 239 ms c. 300 ms d. 250 ms 224. The total propagation delay time from transmission to reception of signals from a ground transmitter to ground receiver with angle of elevation at 10 degrees respectively is: a. 273 ms 9 b. 239 ms c. 275 ms d. 260 ms 225. A satellite which simplify reflects the signal without further amplifications: a. passive satellite 9 b. active satellite c. geostationary satellite d. domestic satellite 226. Essentially a satellite is a radio repeater in the sky:

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a. Transponder 9 b. Comparador c. Duplexer d. Billboard 227. The first satellite to receive and transmit simultaneously a. Telstar I 9 b. Telstar II c. Score d. Echo 228. The first active earth satellite a. Sputnik I 9 b. Explorer I c. Echo d. Molnia 229. Satellite that orbit in a circular pattern with an angular velocity equal to that of the earth a. Geostationary 9 b. Early Bird I c. Syncom I d. Stationary Satellite 230. Satellite that provide services within a single country a. Domsat 9 b. Comsat c. ARABSAT d. EUTELSAT 231. The round-trip propagation delay between two earth stations through a geosynchronous satellite is a. 500 to 600 ms 9 b. 300 to 400 ms c. 600 to 700 ms d. 400 to 500 ms 232. The signal path from transmitter to satellite a. uplink signal 9 b. reflected signal c. incident signal d. downlink signal

233. Designed to receive a signal from a transmitting station on the ground retransmit it to a receiving station located elsewhere a. communication satellite 9 b. repeater c. relay station d. transpondent 234. The signal path from satellite to earth-based receiver a. downlink signal 9 b. uplink signal c. incident signal d. reflected signal 235. A satellite position is measured by its ______ angle with respect to the horizon a. elevation 9 b. depression c. azimuth d. critical 236. The _____ angle measured the satellite position clockwise from the direction of true north. a. azimuth 9 b. elevation c. depression d. critical 237. The earths are that the satellite can receive from or transmit to a. footprint 9 b. primary area c. secondary area d. coverage area 238. Incidentally propose the geostationary scheme or orbit of the satellite in 1940s a. Clarke 9 b. Carl Friedrich Gauss c. Morse d. Stephen Gray

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239. When the satellite are spaced 4 of the 360 complete circle, how many parking space are available? a. 90 9 b. 85 c. 80 d. 80 340. The control routine necessary to keep the satellite in position is referred to as a. station keeping 9 b. station tracking c. station monitoring d. station maintaining 241. Refers to the satellite orientation with respect to the earth a. satellite altitude 9 b. satellite position c. satellite location d. satellite maintaining 242. The farthest distance from earth, a satellite orbit reaches is called a. apogee 9 b. perigee c. line of apsides d. altitude 243. The minimum distance from earth a satellite orbit reaches is called a. perigee 9 b. apogee c. line of apsides d. altitude 244. The first Intelsat satellite that was launched in 1965 was named a. Early Bird I 9 b. Echo c. Telstar I d. Courier 245. The round-trip propagation delay between two earth stations through a geosynchronous satellite is a. 500 to 600 ms 9 b. 400 to 500 ms

c. 200 to 400 ms d. 300 to 400 ms 246. The fist satellite launched for a geosynchronous orbit but unfortunately lost during orbit injection a. Syncom I 9 b. Telstar I c. Sputnik I d. Early Bird I 247. When the elevation angle of a geostationary satellite is 23 and the transmitting frequency is 3840 MHz, what is the free space loss in dB? a. 196 dB 9 b. 200 dB c. 150 dB d. 100 dB 248. What is the propagation delay when a signal is transmitted by an earth station to a geosynchronous satellite about 38, 500 km above earths equator and then received by the same earth station? a. 256 msec 9 b. 128 msec c. 300 msec d. 400 msec 249. What is the free space attenuation of a satellite communication system operating at 36, 000 km above the earth at 5.0 GHz? a. 198 dB 9 b. 200 dB c. 180 dB d. 190 dB 250. The distance between the two antennas of a geostationary satellite system is 22, 300 miles and is operating at a downlink frequency of 12.2 GHz, what is the free space loss in dB? a. 205 dB 9 b. 130 dB

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c. 145 dB d. 166 dB 251. The elevation angle and azimuth angle of a satellite are called a. look angles 9 b. tracking angles c. horizontal angles d. vertical angle 252. A satellite service between earth stations located at fixed geographical points on earth is called a. fixed-point 9 b. mobile c. broadcast d. intersatellite 253. Satellite-to-satellite cross link-link is also called a. intersatellite links (ISLs) 9 b. mobile link c. broadcast link d. fixed point link 254. The most common carrier frequencies used for satellite communications are a. 6/4 and 14/12 GHz bands 9 b. 8/6 and 16/14 GHz bands c. 20/18 and 28/26 GHz bands d. 12/10 and 18/16 GHz bands 255. One (1) angstrom (A) is often used to express wavelength which is equivalent to a. 10-10 meter 9 b. 10-12 meter c. 0.001 micron d. 10-4 meter 256. When making the transition from one energy level to another, the atom absorbs a packet of energy called a. photon 9 b. proton c. electron d. atom

257. Plancks constant is equivalent to a. 6.625 x 10-34 J s 9 b. 6.526 x 10-34 J s c. 6.255 x 10-34 J s d. 5.256 x 10-34 J s 258. Gallium-arsenide has a refractive index of a. 3.6 9 b. 3.4 c. 3.3 d. 3.5 259. The minimum angle of incidence at which a light ray may strike the interface of two media is called a. critical angle 9 b. angle of incidence c. angle of refraction d. angle of reflection 260. A ____ has a central core with a uniform refractive index a. step index 9 b. graded index fiber c. single mode fiber d. multi mode fiber 261. In a ____ there is no cladding and refractive index of the core is nonuniform a. graded-index fiber 9 b. step-index fiber c. single-mode fiber d. multi-mode fiber 262. A figure of merit that is used to measure the light-gathering or light collecting ability of an optical fiber a. Numerical Aperture 9 b. Critical Aperture c. Acceptance Cone d. none of these 263. Developed the first optical maser

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a. Theodore H. Maiman 9 b. A. Javin c. Charles H. Townes d. H. H. Hopkins 264. Developed the helium laser. a. A. Javin 9 b. Theodore H. Maiman c. Charles H. Townes d. H. H. Hopkins 265. A type of laser that uses a mixture of helium and neon enclosed in a glass tube a. Gas laser 9 b. Solid laser c. Liquid laser d. Semiconductor laser 266. The branch of electronics that deals with light. a. Optoelectronics 9 b. Microelectronics c. Optical science d. none of these 267. A scientist who coined the term fiber optics in 1956 a. N. S. Kapany 9 b. A. C. S. Van Heel c. C. W. Hansell d. H. H. Hopkins 268. Light frequencies used in fiber optic systems are between a. 1014 & 1015 Hz 9 b. 1012 & 1014 Hz c. 1015 & 1016 Hz d. 1016 & 1017 Hz 269. Band of light wavelengths that are too long to be seen by the human eye a. Infrared 9 b. Visible c. Ultraviolet d. Amber

270. Band of light wavelengths that are too short to be seen by the human eye a. Ultraviolet 9 b. Infrared c. Visible d. White 271. Band of light wavelengths that the human eye will respond to. a. Visible 9 b. Infrared c. Ultraviolet d. Blue 272. What is the frequency of operation of a dipole cut to length of 5 m? a. 30 MHz 9 b. 3 MHz c. 300 MHz d. 0.3 MHz 273. An amplifier operating over the frequency range of 455 to 460 KHz has a 200 K input resistor. What is the RMS noise voltage at the input to this amplifier if the ambient temperature is 17C? a. 40 V b. 4.0 V 9 c. 400 V d. 4.0 mV 274. The first stage of a two-stage amplifier has a voltage gain of 10, a 600 input resistor, a 1600 equivalent noise resistance and a 27 K output resistor. For the second stage, these values are 25, 81 K, and 1 M, respectively. Calculate the equivalent input-noise resistance of this two-stage amplifier. a. 2, 518 k b. 2, 518 k 9 c. 251.8 k d. 12.518 k

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275. The noise output of a resistor is amplified by a noiseless amplifier having a gain of 60 and a bandwidth of 20 KHz. A meter connected to the output of the amplifier reads 1 mV RMS. IF the bandwidth of the amplifier is reduced to 5 KHz, its gain remaining constant, what does the meter read now? a. 0.5 mV 9 b. 0.5 V c. 5.0 mV d. 5.0 V 276. The front-end of a television receiver, having a bandwidth of 7 MHz, and operating at a temperature of 27C, consists of an amplifier having a gain of 15, followed by a mixer whose gain is 20. The amplifier has a 300 input resistor and a shot noise equivalent resistance of 500 ; for the mixer, these values are 2.2 k and 13.5 k, respectively, and the load resistance of the mixer is 470 k. Calculate the equivalent noise resistance for this television receiver a. 8, 760 b. 876 9 c. 8.76 d. 0.876 277. One of the following is not a useful quantity for comparing the noise performance of receivers. a. input noise voltage 9 b. Equivalent noise resistance c. Noise temperature d. Noise figure 278. Indicate the false statement. Noise figure is defined as: a. the ratio of the s/n power

supplied to the input terminals of a receiver or amplifier to the S/N power supplied to the output or load resistor

b. Noise factor expressed in decibels

c. An unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signals9

d. S/N of an ideal system divided by S/N at the output of the receiver or amplifier under test, both working at the same temperature over the same bandwidth and fed from the same source.

279. Calculate the noise figure of the amplifier whose RF has an input resistance of 1000 and an equivalent shot-noise resistance of 2000 , a gain of 25 and a load resistance of 125 k. Given that the bandwidth is 1.0 MHz and the temperature is 20C, and that the receiver is connected to an antenna with an impedance of 75. a. 30.3 9 b. 3.03 c. 303 d. 0.303 280. A receiver connected to an antenna whose resistance is 50 has an equivalent noise resistance of 30 . Calculate its equivalent noise temperature if the noise figure is equal to 1.6. a. 17.4 K b. 174 K 9 c. 1.74 K d. 17 K 281. What is the frequency tolerance of a standard broadcast station? a. 20.5 Hz b. 20 Hz 9 c. 19.8 Hz d. 33 Hz

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282. What type of antenna site is technically best for an AM broadcast station? a. dry land b. highly elevated c. marshly land 9 d. average terrain 283. A pre-amplifier with a -30 dBm output is connected through a mixer with 20 dB loss of a line amplifier. What must be the voltage gain of the line amplifier to feed a +6 dBm to a 600 line? a. 60 dB 9 b. 72 dB c. 66 dB d. 81 dB 284. In FM, what produces the sidebands? a. Baseband freq. 9 b. Signal amplitude c. Carrier harmonics d. Oscillator 285. Do the harmonics of an FM transmission contain modulation? a. no b. is not possible c. yes 9 d. is possible 286. If a PM transmitter has a tripler and two doublers with an output of 154.32 MHz, what is the crystal frequency? a. 4.6 b. 10.2 c. 4.2864 9 d. 9.8763 287. What type of modulation does the video and audio transmitter at a TV broadcast station employ? a. AM / FM 9 b. FM / FM c. FM / AM d. AM / AM

288. If a TV transmission is assigned to the 82 88 MHz channel, what is the color subcarrier frequency? a. 83.25 b. 86.83 MHz 9 c. 87.75 d. 83.35 289. What is the frequency tolerance for TV transmission? a. 2 kHz b. 2.2 kHz c. 1 kHz 9 d. 1.1 kHz 290. If the aural transmitter of a TV station is modulation 80% by a 5 kHz sine wave, what is the frequency swing of the aural carrier? a. 20 kHz 9 b. 25 kHz c. 10 kHz d. 12.5 kHz 291. Spell out the following abbreviation: FCC, ENG and CCTV a. Federal Communications

Commission Electronic news gathering Closed-circuit tv 9

b. Federal communications commission Electronic network guide closed caption tv

c. Federal commission on communications Electronic network guide Closed-circuit television

d. none of the preceding 292. A 20 dBmV signal level is attenuated in an 18 dB line run, and then amplified by 22 dB. What is the final signal level in volts? a. 13.66 mV b. 9.876 mV c. 15.849 mV 9 d. 16.445 mV

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293. What is the other term for video encryption? a. scrambling 9 b. signature c. encoding d. distortion 294. It is a standard feature on CATV amplifiers that controls the gain with respect to the frequency a. gain control b. equalizer c slope control 9 d. attenuator 295. A must test equipment for CATV: a. multitester b. field level meter 9 c. oscilloscope d. swr meter 296. The starting point for a cable distribution system a. launch amplifier b. receiving system antenna c. TVRO system d. head end 9 297. The signal coverage area of a satellite a. Region b. INTELSAT c. Domestic d. Footprint 9 298. What is the IF range of a satellite TV receiver? a. 950 to 1450 MHz 9 b. 3.7 to 4.2 GHz c. 13.7 to 14.2 GHz d. 40 to 42 MHz 299. A feedhorn having an f/d ratio of 0.375 is to be installed on a 16 foot parabolic dish. Compute for the required spacing of the feedhorn from the vertex of the parabolic antenna

a. 5.24 ft b. 5.5 ft c. 6 ft 9 d. 7.5 ft 300. A device that converts high frequency current into electromagnetic wave is a/an a. antenna 9 b. loudspeaker c. microphone d. transistor 301. The amount of voltage induced in a wire by an electromagnetic wave is determined by the waves a. field strength 9 b. direction of travel c. velocity d. frequency 302. An antenna supported by insulators appears electrically longer than its physical length due to a. end effect 9 b. reflection c. the ionosphere d. the troposphere 303. In a half-wave dipole maximum radiation occurs a. broadside of the antenna 9 b. off the ends c. at 45 angle to the direction of

dipole d. when the end effects are

reduce to zero 304. An electromagnetic wave consists of a. both electric and magnetic

fields 9 b. an electric field only c. a magnetic field only d. non-magnetic field only 305. Antenna polarization is determined by

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a. the direction of the electric field vector 9

b. the frequency of the radiated wave

c. the direction of the radiated wave

d. the direction of the magnitude field vector

306. What is the impedance of a half-wave dipole? a. 73 9 b. 36 c. 100 d. 300 307. The length of a half-wave dipole for 28 MHz is approximately a. 17 ft 9 b. 23 ft c. 30 ft d. 34 ft 308. The quarter-wave vertical antenna requires an excellent ground system to fully utilize the a. mirror image principle 9 b. ground current principle c. troposcatter effect d. end effect 309. A vertical quarter-wave antenna has a. an omnidirectional radiation

pattern 9 b. an input impedance of 300 c. an unidirectional radiation

pattern d. a bidirectional radiation pattern 310. If the transmitter output is 700 watts, transmission line loss is 100 watts and the antenna gain is 10, what is the effective radiated power? a. 6 kW 9 b. 610 kW c. 811 kW d. 7 kW

311. A yagi antenna is an example of a/an a. parasitic array 9 b. driven-array c. log-periodic array d. omnidirectional array 312. The collinear antenna is an example of a/an a. driven-array 9 b. parasitic array c. log-periodic array d. omnidirectional array 313. In a Yagi antenna a. The director is shorter than the

driven element 9 b. The elements are spaced at

least one wavelength apart c. The reflectors are shorter than

the driven element d. There are usually more

reflectors than the direction 314. The angular separation between the two half-power points on the power density radiation pattern a. beamwidth 9 b. bandwidth c. polarization d. spectrum 315. Is said to exist below the ground and is a true mirror image of the actual antenna a. image antenna 9 b. dipole antenna c. Marconi antenna d. Hertz antenna 316. Known as a grounded labda/4 antenna a. Marconi antenna 9 b. Hertz antenna c. Image antenna d. dipole antenna

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317. A device whose function is to radiate electromagnetic energy and/or intercept electromagnetic radiation a. antenna 9 b. transmitter c, transmission line d. transceiver 318. A polar diagram which indicates how well an antenna transmits or receives in different directions a. radiation pattern and field

pattern 9 b. radiation only c. field pattern only d. transmitter 319. Defined as a fictitious resistance which would dissipate as much power as the antenna in question is radiating if it were connected to the same transmission line. a. radiation resistance 9 b. antenna resistance c. ohmic resistance d. ground resistance 320. A resistance that represents the actual image losses caused by the conversion of electrical energy to heat as a result of the resistivity of the various conducting elements of the antenna a. ohmic resistance 9 b. antenna resistance c. radiation resistance d. ground resistance 321. An antenna which has highly directional properties, essentially radiating a beam of electromagnetic radiation a. beam antenna 9 b. half-wave dipole c. Hertz antenna d. Marconi antenna

322. An interesting variation on the dipole antenna is called a. turnstile antenna 9 b. folded dipole c. rhombic antenna d. Yagi-Uda antenna 323. An antenna which is used very frequently but almost entirely as a reception antenna and is usually found on the back of ac-dc table radios a. loop antenna 9 b. turnstile antenna c. folded antenna d. rhombic antenna 324. A comparison of the output, in a particular direction of the antenna in question and a reference antenna a. antenna gain 9 b. antenna efficiency c. directivity d. antenna power 325. The ratio expressed in dB of the output in most optimum direction to the output 180 away from the optimum direction a. front-to-back ratio 9 b. antenna gain c. directivity d. antenna power 326. The elementary doublet is a theoretical antenna which is used as a standard to which all the other antenna characteristics can be compared and is sometimes called as a. Hertzian dipole 9 b. Marconi antenna c. Yagi antenna d. loop antenna 327. Defined as the ratio of the power density in a particular direction of one antenna to the power density that would be radiated by an isotropic antenna

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a. directivity gain 9 b. antenna gain c. efficiency d. power gain 328. The gain of a Hertzian dipole with respect to an isotropic antenna is a. 1.76 dB 9 b. 2.15 dB c. 4.15 dB d. 5.15 dB 329. The gain of a half-wave dipole compared to the isotropic antenna is a. 2.15 dB 9 b. 3.15 dB c. 4.15 dB d. 5.15 dB 330. The angle created by comparing the half-power points (3dB) on the main radiation lobe to its maximum power point a. beamwidth 9 b. bandwidth c. polarization d. beamwidth between nulls 331. A network composed of reactances and transformers used to provide matching a. antenna coupler or coupling

network 9 b. antenna coupler and coupling

network c. Thevenins network d. Nortons network 332. How much power will an antenna having a radiation resistance of 50 radiate when it is fed 10 A? a. 5 kW 9 b. 500 kW c. 0.5 kW d. 5 kW 333. What is the radiation resistance of an antenna which radiates 20 KW when it draws 20 A?

a. 50 9 b. 5 c. 5 K d. 500 334. How much current flows into the antenna having a radiation resistance of 300 radiating 5 kW? a. 4.08 A 9 b. 5.08 A c. 3.08 A d. 2.08 A 335. What is the Q of an antenna with a bandwidth of 6 MHz and a frequency of 300 MHz a. 50 9 b. 0.5 c. 5 d. 500 336. What is the length of a practical dipole used to receive a 6 MHz radio signals? a. 23.75 m 9 b. 26.75 m c. 25.75 m d. 24.75 m 337. Calculate the noise figure of the amplifier whose REQ equals 2518 (RT = 600) if its driven by a generator whose output impedance is 50. a. 39.4 9 b. 3.94 c. 394 d. 0.394