Kennedy All

7/31/2019 Kennedy All

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1. In a communications system; noise is most likely to affect the signala. at the transmitterb. in the channelc. in the information sourced. at the destination

2. Indicate the false statement. Fourier analysis shows that a sawtooth wave consist ofa. fundamental and subharmonic sine wavesb. a fundamental sine wave and an infinite number of harmonicsc. fundamental and harmonic sine waves whose amplitude decreases with the harmonic numberd. sinusoidal voltages; some of which are small enough to ignore in practice

3. Indicate the false statement. Modulation is used toa. reduce the bandwidth usedb. separate differing transmissionsc. ensure that intelligence may be transmitted over long distancesd. allow the use of practicable antennas

4. Indicate the false statement. From the transmitter the signal deteriorationbecause of noise is usuallya. unwanted energyb. predictable in character

c. present in the transmitterd. due to any cause

5. Indicate the true statement. Most receivers conforms to thea. amplitude-modulated groupb. frequency-modulated groupc. superheterodyne groupd. tuned radio frequency receiver group

6. Indicate the false statement. The need for modulation can best be exemplified by the following.a. Antenna lengths will be approximately /4 longb. An antenna in the standard broadcast AM band is 16;000 ft

c. All sound is concentrated from 20 Hz to 20 kHzd. A message is composed of unpredictable variations in both amplitude and frequency

7. Indicate the true statement. The process of sending and receiving started as early asa. the middle 1930sb. 1850c. the beginning of the twentieth centuryd. the 1840s

8. Which of the steps is not included in the process of reception?a. decoding

b. encodingc. storaged. interpretation

9. The acoustic channel is used for which of the following?a. UHF communicationsb. single-sideband communicationc. television communicationsd. person-to-person voice communications



10. Amplitude modulation is the process ofa. superimposing a low frequency on a high frequencyb. superimposing a high frequency on a low frequencyc. carrier interruptiond. frequency shift and phase shift

1. One of the following types of noise becomes of great importance at high frequencies. It is thea. shot noiseb. random noisec. impulse noised. transit-time noise

2. Indicate the false statement.a. HF mixers are generally noisier than HF amplifiers.b. Impulse noise voltage is independent of bandwidth.c. Thermal noise is independent of the frequency at which it is measured.d. Industrial noise is usually of the impulse type.

3. The value of a resistor creating thermal noise is doubled. The noise power generator is thereforea. halvedb. quadrupledc. doubled

d. unchanged

4. One of the following is not a useful quantity for comparing the noise performance of receivers:a. Input noise voltageb. Equivalent noise resistancec. Noise temperatured. Noise figure

5. Indicate the noise whose source is in a category different from that of the other three.a. Solar noiseb. Cosmic noise

c. Atmospheric noised. Galactic noise

6. Indicate the false statement. The square of the thermal noise voltage generated by a resistor is proportional toa. its resistanceb. its temperaturec. Boltzmanns constantd. the bandwidth over which it is measured

7. Which of broad classifications of noise are most difficult to treat?a. noise generated in the receiverb. noise generated in the transmitter

c. externally generated noised. internally generated noise

8. Space noise generally covers a wide frequency spectrum; but the strongest interference occursa. between 8 MHz and 1.43 GHzb. below 20 Mhzc. between 20 to 120 MHzd. above 1.5 GHz



9. When dealing with random noise calculations it must be remembered thata. all calculations are based on peak to peak valuesb. calculations are based on peak valuesc. calculations are based on average valuesd. calculations are based on RMS values

10. Which of the following is the most reliable measurement for comparing amplifier noise characteristics?a. signal-to-noise ratiob. noise factorc. shot noised. thermal noise agitation

11. Which of the following statements is true ?a. Random noise power is inversely proportional to bandwidthb. Flicker is sometimes called demodulation noisec. Noise is mixers is caused by inadequate image frequency rejectiond. A random voltage across a resistance cannot be calculated

1. If the plate supply voltage for a plate-modulated class C amplifier is V; themaximum plate-cathode voltage could be almost as high asa. 4Vb. 3Vc. 2V

d. 1V

2. In a low-level AM system; amplifiers following the modulated stage must bea. linear devicesb. harmonic devicesc. class C amplifiersd. nonlinear devices

3. If the carrier of a 100 percent modulated AM wave is suppressed; the percentage power saving will bea. 50b. 150c. 100

d. 66.66

4. Leak-type bias is used in a plate-modulated class C amplifier toa. prevent tuned circuit dampingb. prevent excessive grid currentc. prevent overmodulationd. increase the bandwidth

5. The output stage of a television transmitter is most likely to be aa. plate-modulated class C amplifierb. grid-modulated class C amplifierc. screen-modulated class C amplifierd. grid-modulated class A amplifier

6. The modulation index of an AM wave is changed from 0 to 1. The transmitted power isa. unchangedb. halvedc. doubledd. increase by 50 percent

7. One of the advantages of the base modulation over collector modulation of a transistor class C amplifier is



a. the lower modulating power requiredb. higher power output per transistorc. better efficiencyd. better linearity

8. A carrier is simultaneously modulated by two sine waves with modulation indices of 0.3 and 0.4; the total modulation indexa. is 1b. cannot be calculated unless the phase relations are knownc. is 0.5d. is 0.7

9. Amplitude modulation is used for broadcasting becausea. it is more noise immune than other modulation systems.b. Compared with other systems it requires less transmitting powerc. its use avoids receiver complexity.d. no other modulation system can provide the necessary bandwidth for high fidelity

10. What is the ratio of modulating power to total power at 100 percent modulation?a. 1:3b. 1:2c. 2:3

d. None of the above

1. Indicate the false statement regarding the advantages of SSB over double sideband; full-carrier AMa. More channel space is available.b. Transmitter circuits must be more stable; giving better reception.c. The signal is more noise-resistantd. Much less power is required for the same signal strength

2. When the modulation index of an AM wave is doubled; the antenna current is also doubled. The AM system being used isa. Single-sideband; full carrier (H3E)b. Vestigial sideband (C3F)

c. Single-sideband; suppressed carrier (J3E)d. Double-sideband; full carrier (A3E)

3. Indicate which one of the following advantages of the phase cancellation method of obtaining SSB over the filter method is false :a. Switching from one sideband to the other is simpler.b. It is possible to generate SSB at any frequency.c. SSB with lower audio frequencies present can be generatedd. There are more balanced modulators; therefore the carrier is suppressed better.

4. The most commonly used filters in SSB generation area. mechanical

b. RCc. LCd. low-pass

5. In an SSB transmitter; one is most likely to find aa. class C audio amplifierb. tuned modulatorc. class B RF amplifierd. class A RF output amplifier



6. Indicate in which one of the following only one sideband is transmitted.a. H3Eb. A3Ec. B8Ed. C3F

7. One of the following cannot be used to remove the unwanted sideband in SSB.This is thea. filter systemb. phase-shift methodc. third methodd. balanced modulator

8. R3E modulation is sometimes used toa. allow the receiver to have a frequency synthesizerb. simplify the frequency stability problem in receptionc. reduce the power that must be transmittedd. reduce the bandwidth required for transmission

9. To provide two or more voice circuits with the same carrier; it is necessaryto usea. ISBb. carrier insertionc. SSB with pilot carrier

d. Lincompex

10. Vestigal sideband modulation (C3F) is normally used fora. HF point-to-point communicationsb. monoaural broadc astingc. TV broadcastingd. stereo broadcasting

1. In the stabilize reactance modulator AFC system;a. the discriminator must have a fast time constant to prevent demodulationb. the higher the discriminator frequency; the better the oscillator frequency stabilityc. the discriminator frequency must not be too low; or the system will fail

d. phase modulation is converted into FM by the equalizer circuit

2. In the spectrum of a frequency-modulated wavea. the carrier frequency disappears when the modulation index is largeb. the amplitude of any sideband depends on the modulation indexc. the total number of sidebands depends on the modulation indexd. the carrier frequency cannot disappear

3. The difference between phase and frequency modulationa. is purely theoretical because they are the same in practiceb. is too great to make the two system compatiblec. lies in the poorer audio response of phase modulationd. lies in the different definitions of the modulation index

4. Indicate the false statement regarding the Armstrong modulation systema. The system is basically phase; not frequency modulation;b. AFC is not needed; as crystal oscillator is used.c. Frequency multiplication must be used.d. Equalization is unnecessary

5. An FM signal with a modulation index m is passed through a frequency f tripler. The wave in the output of the tripler will have a modulation index ofa. m /3 f



b. m fc. 3m fd. 9m f 6. An FM signal with a deviation d is passed through a mixer; and has its frequency reduced fivefold. The deviation in the output of the mixer isa. 5db. Indeterminatec. d/ 5d. d

7. A pre-emphasis circuit provides extra noise immunity bya. boosting the bass frequenciesb. amplifying the higher audio frequenciesc. preamplifying the whole audio bandd. converting the phase modulation to FM

8. Since noise phase-modulates the FM wave; as the noise sidebandfrequency approaches the carrier frequency; the noise amplitudea. remains constantb. is decreasedc. is increasedd. is equalized

9. When the modulating frequency is doubled; the modulation index is halved; andthe modulating voltage remains constant. The modulation system isa. amplitude modulationb. phase modulationc. frequency modulationd. any of the three

10. Indicate which one of the following is not an advantage of FM over AM:a. Better noise immunity is providedb. Lower bandwidth is requiredc. The transmitted power is more usefuld. Less modulating power is required

11. One of the following is an indirect way of generating FM. This is thea. reactance FET modulatorb. varactor diode modulatorc. Armstrong modulatord. reactance bipolar transistor modulator

12. In an FM stereo multiplex transmission; thea. sum signal modulates 19 kHz subcarrierb. difference signal modulates the 19 kHz subcarrierc. difference signal modulates the 38 kHz subcarrierd. difference signal modulates the 67 kHz subcarrier

1. Indicate which of the following statements about the advantages of the phase

discriminator over the slope detector is false :a. Much easier alignmentb. Better linearityc. Greater limitingd. Fewer tuned circuits

2. Show which of the following statements about the amplitude limiter is untrue:a. The circuit is always biased in class C; by virtue of the leak-type bias.b. When the input increases past the threshold of the limiting; the gain decreas



es to keep the output constant.c. The output must be tunedd. Leak-type bias must be used

3. In a radio receiver with simple AGCa. an increase in signal strength produces more AGCb. the audio stage gain is normally controlled by the AGCc. the faster the AGC time constant the more accurate the outputd. the highest AGC voltage is produced

4. In a broadcast superheterodyne receiver; thea. local oscillator operates below the signal frequencyb. mixer input must be tuned to the signal frequencyc. local oscillator frequency is normally double the IFd. RF amplifier normally works at 455 kHz above the carrier frequency

5. To prevent overloading of the IF amplifier in a receiver; one should usea. squelchb. variable sensitivityc. variable selectivityd. double conversion

6. A superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200kHz. The image frequency is

a. 750 kHzb. 900 kHzc. 1650 kHzd. 2100 kHz

7. In a ratio detectora. the linearity is worse than in phase discriminatorb. stabilization against signal strength variations is providedc. the output is twice that obtainable from a similar phase discriminatord. the circuit is the same as in a discriminator; except that the diodes are reversed

8. The typical squelch circuit cuts off

a. an audio amplifier when the carrier is absentb. RF interference when the signal is weakc. An IF amplifier when the AGC is maximumd. An IF amplifier when the AGC is minimum

9. Indicate the false statement in connection with communicationsreceivers.a. The noise limiter cuts off the receivers output during a noisepulse.b. A product demodulator could be used for the reception of Morse code.c. Double conversion is used to improve image rejectiond. Variable sensitivity is used to eliminate selective fading

10. The controlled oscillator synthesizer is sometimes preferred over thedirect one becausea. it is a simpler piece of equipmentb. its frequency stability is betterc. it does not require crystal oscillatord. it is relatively free of spurious frequency

11. The frequency generated by each decade in a direct frequencysynthesizer is much higher than the frequency shown; this is done toa. reduce the spurious frequency problem



b. increase the frequency stability of the synthesizerc. reduce the number of decadesd. reduce the number of crystals required

12. Indicate which of the following circuits could not demodulate SSB:a. Balance modulatorb. Product modulatorc. BFOd. Phase discriminator

13. If a FET is used as the first AF amplifier in a transistor receiver;this will have the effect ofa. improving the effectiveness of the AGCb. reducing the effect of negative-peak clippingc. reducing the effect of noise at low modulation depthsd. improving the selectivity of the receiver

14. Indicate the false statement. The superheterodyne receiver replacedthe TRF receiver because the latter suffered froma. gain variation over the frequency coverage rangeb. insufficient gain and sensitivityc. inadequate selectivity at high frequenciesd. instability

15. The image frequency of a superheterodyne receivera. is created within the receiver itselfb. is due to insufficient adjacent channel rejectionc. is not rejected be the IF tuned circuitsd. is independent of the frequency to which the receiver is tuned

16. One of the main functions of the RF amplifier in a superheterodynereceiver is toa. provide improved trackingb. permit better adjacent-channel rejectionc. increase the tuning range of the receiverd. improve the rejection of the image frequency

17. A receiver has poor IF selectivity. It will therefore also have poora. blockingb. double-spottingc. diversion receptiond. sensitivity

18. Three-point tracking is achieved witha. variable selectivity

b. the padder capacitorc. double spottingd. double conversion

19. The local oscillator of a broadcast receiver is tuned to a frequencyhigher than the incoming frequencya. to help the image frequency rejectionb. to permit easier trackingc. because otherwise an intermediate frequency could not be producedd. to allow adequate frequency coverage without switching



20. If the intermediate frequency is very high (indicate false statement)a. image frequency rejection is very goodb. the local oscillator need not be extremely stablec. the selectivity will be po ord. tracking will be improved

21. A low ratio of the ac to the dc load impedance of a diode detectorresults ina. diagonal clippingb. poor AGC operationc. negative-peak clippingd. poor AF response

22. One of the following cannot be used to demodulate SSB:a. Product detectorb. Diode Balance modulatorc. Bipolar transistor balanced modulatord. Complete phase-shift generator

23. Indicate the false statement. Noting that no carrier is transmitterwith J3E; we see thata. the receiver cannot use a phase comparator for AFCb. adjacent-channel rejection is more difficult

c. production of AGC is a rather complicated processd. the transmission is not compatible with A3E

24. When a receiver has good blocking performance; this means thata. it does not suffer from double-spottingb. its image frequency rejection is poorc. it is unaffected by AGC derived from nearby transmissionsd. its detector suffers from burnout

25. An AM receiver uses a diode detector for demodulation. This enables itsatisfactorily to receivea. single-sideband; suppressed-carrierb. single-sideband; reduced-carrier

c. ISBd. Single-sideband; full-carrier

TRANSMISSION LINES

1. Indicate the false statement. The SWR on a transmission line isinfinity; the line is terminated ina. a short circuitb. a complex impedancec. an open circuitd. a pure reactance

2. A (75- j 50)- is connected to a coaxial transmission line of Z = 75 ;Oat 10 GHz. The best method of matching consists in connectinga. a short-circuited stub at the loadb. an inductance at the loadc. a capacitance at some specific distanced. a short-circuited stub at some specific distance from the load



3. The velocity factor of a transmission linea. depends on the dielectric constant of the material usedb. increases the velocity along the transmission linec. is govern by the skin effectd. is higher for a solid dielectric than for air

4. Impedance inversion may be obtained witha. a short-circuited stubb. an open-circuited stubc. a quarter-wave lined. a half-wave line

5. Short-circuited stubs are preferred to open-circuited stubs because thelatter area. more difficult to make an connectb. made of a transmis sion line with a different characteristic impedancec. liable to radiated. incapable of giving a full range of reactances

6. For transmission-line load matching over a range of frequencies; it isbest to use aa. balunb. broadband directional couplerc. double stub

d. single stub of adjustable position

7. The main disadvantage of the two-hole directional coupler isa. low directional couplingb. poor directivityc. high SWRd. narrow bandwidth

8. To couple a coaxial line to a parallel-wire line; it is best to use aa. slotted lineb. balunc. directional couplerd. quarter-wave transformer

9. Indicate the three types of transmission line energy losses.a. I R ; R ; and temperature 2Lb. Radiation; I R ; and dielectric heating 2c. Dielectric separation; insulation breakdown; and radiationd. Conductor heating; dielectric heating; and radiation resistance.

10. Indicate the true statement below. The directional coupler isa. a device used to connect a transmitter to a directional antennab. a coupling device for matching impedancec. a device used to measure transmission line powerd. an SWR measuring instrument

RADIATION AND PROPAGATION OF WAVES

1. Indicate which one of the following terms applies to troposcatterpropagation:a. SIDsb. Fadingc. Atmospheric stormsd. Faraday rotation

2. VLF waves are used for some type of services because



a. of the low powers requiredb. the transmitting antennas are of convenient sizec. they are very reliabled. the penetrate the ionosphere easily

3. Indicate which of the following frequencies cannot be used for reliablebeyond-the-horizon terrestrial communications without repeaters:a. 20 kHzb. 15 MHzc. 900 MHzd. 12 GHz4. High-frequency waves area. absorbed by the F layer 2b. reflected by the D layerc. capable of use for long-distance communications on the moond. affected by the solar cycle

5. Distances near the skip distance should be used for the sky-wavepropagationa. to avoid tiltingb. to prevent sky-wave and upper ray interferencec. to avoid the Faraday effectd. so as nor to exceed the critical frequency

6. A ship-to-ship communications system is plagued by fading. The bestsolution seems to be use ofa. a more directional antennab. a broadband antennac. frequency diversityd. space diversity

7. A range of microwave frequencies more easily passed by the atmospherethan are the others is called aa. windowb. critical frequencyc. gyro frequency ranged. resonance in the atmosphere

8. Frequencies in the UHF range normally propagate by means ofa. ground wavesb. sky wavesc. surface wavesd. space waves

9. Tropospheric scatter is used with frequencies in the following range:a. HFb. VHFc. UHFd. VLF

10. The ground wave eventually disappears; as one moves away from thetransmitter; because ofa. interference from the sky waveb. loss of line-of-sight conditionsc. maximum single-hop distance limitationd. tilting

11. In electromagnetic waves; polarizationa. is caused by reflectionb. is due to the transverse nature of the waves



c. results from the longitudinal nature of the wavesd. is always vertical in an isotropic medium

12. As electromagnetic waves travel in free space; only one of thefollowing can happen to them:a. absorptionb. attenuationc. refractiond. reflection

13. The absorption of radio waves by the atmosphere depends ona. their frequencyb. their distance from the transmitterc. the polarization of the wavesd. the polarization of the atmosphere

14. Electromagnetic waves are refracted when theya. pass into a medium of different dielectric constantb. are polarized at right angles to the direction of propagationc. encounter a perfectly conducting planed. pass through a small slot in a conducting plane

15. Diffraction of electromagnetic wavesa. is caused by reflections from the ground

b. arises only with spherical wavefrontsc. will occur when the waves pass through a large slotd. may occur around the edge of a sharp obstacle

16. When microwave signals follow the curvature of the earth; this isknown asa. the Fara day effectb. ductingc. tropospheric scatterd. ionospheric reflection

17. Helical antennas are often used for satellite tracking at VHF becauseof

a. troposcatterb. superrefractionc. ionospheric refractiond. the Faraday effe

ANTENNAS

1. An ungrounded antenna near the grounda. acts as a single antenna of twice the heightb. is unlikely to need a ground screenc. acts as an antenna arrayd. must be horizontally polarized

2. One of the following consists of nonresonant antennas:a. The rhombic antennab. The folded dipolec. The end-fire arrayd. The broadside array

3. One of the following is very useful as a multiband HF receivingantenna. This is the:a. conical hornb. folded dipole



c. log periodicd. square loop

4. Which of the following antennas is best excited from a waveguide?a. Bicon icalb. Hornc. Helicald. Discone

5. Indicate which of the following reasons for using a counterpoise withantenna is false :a. Impossibility of a good ground connectionb. Protection of personnel working undergroundc. Provision of an earth for the antennad. Rockiness of the ground

6. One of the following is not a reason for the use of an antenna coupler:a. To make the antenna look resistiveb. To provide the output amplifier with the correct load impedancec. To discriminate against harmonicsd. To prevent reradiation of the local oscillator

7. Indicate the antenna that is not widebandL:a. Discone

b. Folded Dipolec. Helicald. Marconi

8. Indicate which one of the following reasons for the use of a groundscreen with antennas is false:a. Impossibility of a good ground connection

b. Provision of an earth for the antennac. Protection of personnel working underneathd. Improvement of the radiation pattern of the antenna

9. Which one of the following terms does not apply to the Yagi-Uda array?a. Good bandwidthb. Parasitic elementsc. Folded dipoled. High gain

10. An antenna that is currently polarized us thea. helicalb. small circular loop

c. parabolic reflectord. Yagi-Uda

11. The standard reference antenna for the directive gain is thea. infinitesimal dipoleb. isotropic antennac. elementary doubletd. half-wave dipole

12. Top loading is sometimes used with an antenna in order to increase its



a. effective heightb. bandwidthc. beamwidthd. input capacitance

13. Cassegrain feed is used with a parabolic reflector toa. increase the gain of the systemb. increase the beamwidth of the systemc. reduce the size of the main reflectord. allow the feed to be placed at a convenient point

14. Zoning is used with a dielectric antenna in order toa. reduce the bulk of the lenseb. increase the bandwidth of the lensc. increase pin-point focusingd. correct the curvature of the wavefront from a horn that is too short

15. A helical antenna is used for satellite tracking because of itsa. circular polarizationb. maneuverabilityc. broad bandwidthd. good front-to-back ratio

16. The discone antenna isa. useful direction-finding antennab. used as a radar receiving antennac. circularly polarized like other circular antennasd. useful as UHF receiving antennas

17. One of the following is not an omnidirectional antenna:a. Half-wave dipoleb. Log-periodicc. Disconed. Marconi

WAVEGUIDES; RESONATORS AND COMPONENTS

1. When an electromagnetic waves are propagated in a waveguidea. they travel along a broader walls of the guideb. they are reflected from the walls but do not travel along themc. they travel through the dielectric without touching the wallsd. they travel along all four walls of the waveguide

2. Waveguides are used mainly for microwave signals becausea. they depend on straight-line propagation which applies to microwavesonlyb. losses would be too heavy at lower frequenciesc. there are no generators powerful enough to excite them at lower

frequenciesd. they would be too bulky at lower frequencies

3. The wavelength of a wave in a waveguidea. is greater than of free spaceb. depends only on the waveguide dimensions and the free-spacewavelengthc. is inversely proportional to the phase velocityd. is directly propotional to the group velocity



4. The main difference between the operation of transmission lines andwaveguides is thata. the latter are not distributed; like transmission linesb. the former can use stubs and quarter-wave transformers; unlike thelatterc. transmission lines use the principal mode of propagation; andtherefore do not suffer from low-frequency cut-offd. terms such as impedance matching and standing-wave ratio cannot beapplied to waveguides

5. Compared with equivalent transmission lines; 3-GHz waveguides (indicatefalse statement)a. are less lossyb. can carry highe r powersc. are less bulkyd. have lower attenuation

6. When a particular mode is excited in a waveguide; three appears anextra electric component; in the direction of propagation. The resultingmode isa. transverse-electricb. transverse-magneticc. longitudinald. transverse-electromagnetic

7. When electromagnetic waves are reflected at an angle from a wall; theirwavelength along the wall isa. the same as in free spaceb. the same as the wavelength perpendicular to the wallc. shortened because of Doppler effectd. greater than in the actual direction of propagation

8. As a result of reflections from a plane conducting wall;electromagnetic waves acquire an apparent velocity greater than thevelocity of light in space. This is called thea. velocity of propagationb. normal velocity

c. group velocityd. phase velocity

9. Indicate the false statement. When the free space wavelength of asignal equals the cut-off wavelength of the guidea. the group velocity of the signal becomes zerob. the phase velocity of the signal becomes infinitec. the characteristic impedance of the guide becomes infinited. the wavelength within the waveguide becomes infinite

10. A signal propagation in a waveguide has a full wave of electricintensity change between the two further walls; and no component of theelectric field in the direction of propagation. The mode is

a. TE 1;1b. TE 1;0c. TM 2;2d. TE 2;0

11. The dominant mode of propagation is preferred with rectangularwaveguides because (indicate false statement)a. it leads to the smallest waveguide dimensions



b. the resulting impedance can be matched directly to coaxial linesc. it is easier than the other modesd. propagation of it without any spurious generation can be ensured

12. A choke flange may be used to couple two waveguidesa. to help in the alignment of the waveguidesb. because it is simpler than any other joinc. to compensate for discontinuities at the joind. to increase the bandwidth of the system

13. In order to couple two generators to a waveguide system withoutcoupling them to each other; on could not use aa. at-racerb. E -plane Tc. hybrid ringd. magic T

14. Which of the following waveguides tuning components is not easilyadjustable?a. Screwb. Stubc. Irisd. Plunger

15. A piston attenuator is aa. vane attenuatorb. waveguide below cutoffc. mode filterd. flap attenuator

16. Cylindrical cavity resonators are not used with klystrons because theyhavea. a Q that is too lowb. a shape whose resonant frequency is too difficult to calculatec. harmonically related resonant frequenciesd. too heavy losses

17. A directional coupler with three or more holes is sometimes used inpreference to the two-hole couplera. because it is more efficientb. to increase coupling of the signalc. to reduce spurious mode generationd. to increase the bandwidth of the system

18. A ferrite isa. a nonconductive with magnetic propertiesb. an intemetallic compound with particularly good conductivityc. an insulator which heavily attenuates magnetic fieldsd. a microwave semiconductor invented by Faraday

19. Manganese ferrite may be used as a (indicate false answer)a. circulatorb. isolatorc. garnetd. phase shifter

20. The maximum power that may be handled by a ferrite component islimited by thea. Curie temperature



b. Saturation magnetizationc. line widthd. gyromagnetic resonance

21. A PIN diode isa. a metal semiconductor point-contact diodeb. a microwave mixer diodec. often used as a microwave detectord. suitable for use as a microwave switch

22. A duplexer is useda. to couple two different antennas to a transmitter without mutualinterferenceb. to allow the one antenna to be used for reception or retransmissionwithout mutual interferencec. to prevent interference between two antennas when they are connectedto a receiverd. to increase the speed of the pulses in pulses in pulsed radar

23. For some applications; circular waveguides may be preferred torectangular ones because ofa. the smaller cross section needed at any frequencyb. lower attenuationc. freedom from spurious modesd. rotation of polarization

24. Indicate which of the following cannot be followed by the word'waveguide':a. Ellipticalb. Flexiblec. Coaxiald. Ridged

25. In order to reduce cross-sectional dimensions; the waveguide to use isa. circularb. ridgedc. rectangulard. flexible

26. For low attenuation; the best transmission medium isa. flexible waveguideb. ridged waveguidec. rectangular waveguided. coaxial line

MICROWAVE TUBES AND CIRCUITS

1. A microwave tube amplifier uses an axial magnetic field and a radialelectric field. This is thea. reflex klystronb. coaxial magnetronc. traveling-wave magnetrond. CFA

2. One of the following is unlikely to be used as a pulsed device. It is



thea. multicavity klystronb. BWOc. CFAd. TWT

3. One of the reasons why vacuum tubes eventually fail at microwavefrequencies is that theira. noise figure increasesb. transit time becomes too shortc. shunt capactitive reactances become too larged. series inductive reactances become too small

4. Indicate the false statement. Transit time in microwave tubes will bereduced ifa. the electrodes are brought closer togetherb. a higher anode current is usedc. multiple or coaxial leads are usedd. the anode voltage is made larger

5. The multicavity klystrona. is not a good low-level amplifier because of noiseb. has a higher repeller voltage to ensure a rapid transit time

c. is not suitable for pulsed operationd. needs a long transit time through the buncher cavity to ensurecurrent modulation

6. Indicate the false statement. Klystron amplifiers may use intermediatecavities toa. prevent the oscillations that occur in two-cavity klystronsb. increase the bandwidth of the devicec. improve the power gaind. increase the efficiency of the klystron

7. The TWT is sometimes preferred to the multicavity klystron amplifier;because it

a. is more efficientb. has a greater bandwidthc. has a higher number of modesd. produces a higher output power

8. The transit time in the repeller space of a reflex klystron must be n +¾ cycles to ensure thata. electrons are accelerated by the gap voltage on their returnb. returning electrons give energy to the gap oscillationsc. it is equal to the period of the cavity oscillationsd. the repeller is not damaged by striking electrons

9. The cavity magnetron uses strapping to

a. prevent mode jumpingb. prevent cathode back-heatingc. ensure bunchingd. improve the phase-focusing effect

10. A magnetic field is used in the cavity magnetron toa. prevent anode current in the absence of oscillationb. ensure that the oscillations are pulsedc. help in focusing the electron beam; thus preventing spreadingd. ensure that the electrons will orbit around the cathode



11. To avoid difficulties with strapping at high frequencies; the type ofcavity structure used in the magnetron is tha. hole-and-slotb. slotc. vaned. rising sun

12. The primary purpose of the helix in a traveling-wave tube is toa. prevent the electron beam from spreading in the long tubeb. reduce the axial velocity of the RF fieldc. ensure broadband operationd. reduce the noise figure

13. The attenuator is used in the traveling-wave tube toa. help bunchingb. prevent oscillationsc. prevent saturationd. increase gain

14. Periodic permanent-magnet focusing is used with TWTs toa. allow pulsed operationb. improve electron bunchingc. avoid the bulk of an electromagnet

d. allow coupled-cavity operation at the highest frequencies

15. The TWT is sometimes preferred to the magnetron as a radar transmitteroutput tube because it isa. capable of a longer duty cycleb. a more efficient bandwidth

c. more broadbandd. less noisy

16. A magnetron whose oscillating frequency is electronically adjustableover a wide range is called aa. coaxial magnetronb. dither-tuned magnetronc. freq uency-agile magnetrond. VTM

17. Indicate which of the following is not a TWT slow-wave structure:a. Periodic-permanent magnetb. Coupled cavity

c. Helixd. Ring-bar

18. The glass tube of a TWT may be coated with aquadag toa. help focusingb. provide attenuationc. improve bunchingd. increase gain

19. A backward-wave oscillator is based on the



a. rising-sun magnetronb. crossed-field amplifierc. coaxial magnetrond. traveling-wave tube

SEMICONDUCTOR MICROWAVE DEVICES AND CIRCUITS

1. A parametric amplifier must be cooleda. because parametric amplification generates a lot of heatb. to increase bandwidthc. because it cannot operate at room temperatured. to improve the noise performance

2. A ruby maser amplifier must be cooleda. because maser amplification generates a lot of heatb. to increase bandwidthc. because it cannot operate at room temperatured. to improve the noise performance

3. A disadvantage of microstrip compared with stripline is that microstripa. does not readily lend itself to printed circuit techniquesb. is more likely to radiatec. is bulkierd. is more expensive and complex to manufacture

4. The transmission system using two ground plane isa. microstripb. elliptical waveguidec. parallel-wire lined. stripline

5. Indicate the false statement. An advantage of stripline over wveguideis itsa. smaller bulkb. greater bandwidthc. higher power-handling capabilityd. greater compatibility with solid-state devices

6. Indicate the false statement. An advantage of stripline over microstripis itsa. easier integration with semiconductor devicesb. lower tendency to radiatec. higher isolation between adjacent circuitsd. higher Q

7. Surface acoustics waves propagate ina. gallium arsenideb. indium phosphidec. striplined. quartz crystal

8. SAW devices may be used asa. transmission media like striplineb. filters



c. UHF amplifiersd. Oscillators at millimeter frequencies

9. Indicate the false statement. FETs are preferred to bipolar transistorsat the highest frequencies because theya. are less noisyb. lend themselves more easily to integrationc. are capable of higher effecienciesd. can provide higher gains

10. For best low-level noise performance in the X-band; an amplifiershould usea. a bipolar transistorb. a Gunn diodec. a step-recovery dioded. an IMPATT diode

11. The biggest advantage of the TRAPATT diode over the IMPATT diode isitsa. lower noiseb. higher efficiencyc. ability to operator at higher frequenciesd. lesser sensitivity to harmonics

12. Indicate which of the following diodes will produce the highest pulsedpower output:a. Varatorb. Gunnc. Schottky barrierd. RIMPATT

13. Indicate which of the following diodes does not use negativeresistnace in its operation:a. Backwardb. Gunnc. IMPATTd. Tunnel

14. One of the following is not used as a microwave mixer or detector:a. Crystal diodeb. Schottky-barrier diodec. Backward dioded. PIN diode

15. One of the following microwave diodes is suitable for very low-poweroscillators only:a. Tunnelb. avalanchec. Gunnd. IMPATT

16. The transferred-electron bulk effect occurs ina. germaniumb. gallium arsenidec. silicon



d. metal semiconductor junctions

17. The gain-bandwidth frequency of a microwave transistor; f ; is theTfrequency at which thea. alpha of the transistor falls by 3 dBb. beta of the transistor falls by 3 dBc. power gain of the transistor falls to unityd. beta of the transistor falls to unity

18. For a microwave transistor to operate at the highest frequencies; the(indicate the false answer)a. collector voltage must be largeb. collector current must be highc. base should be thind. emitter area must be large

19. A varactor diode may be useful at microwave frequencies (indicate thefalse answer)a. for electronic tuningb. for frequency mul tiplicationc. as an oscillatord. as a parametric amplifier

20. If high-order frequency multiplication is required from a diodemultiplier;a. the resistive cutoff frequency must be highb. a small value of the base resistance is requiredc. a step-recovery diode must be usedd. a large range of capacitance variation is needed

21. A parametric amplifier has an input and output frequency of 2.25 GHz;and is pumped at 4.5 GHz. It isa. traveling-wave amplifierb. degenerative amplifierc. lower-sideband up-converterd. upper-sideband up-converter

22. A nondegenerate parametric amplifier has an input frequency f and aipump frequency f . Then idler frequency ispa. f ib. 2 f ic. f f i pd. f - f p i 23. Traveling-wave parametric amplifiers are used toa. provide a greater gainb. reduce the number of varactor diodes required

c. avoid the need for coolingd. provide greater bandwidth

24. A parametric amplifier sometimes uses a circulator toa. prevent noise feedbackb. allow the antenna to be used simultaneously for transmission andreceptionc. separate the signal and idler frequenciesd. permit more efficient pumping



25. The nondegenerate one-port parametric amplifier should have a highratio of pump to signal frequency because thisa. permits satisfactory high- frequency operationb. yields a low noise figurec. reduce the pump power requiredd. permits satisfactory

26. The tunnel diodea. has a tiny hole through its center to facilitate tunnelingb. is a point-contact diode with a very high reverse resistancec. uses a high doping level to provide a narrow junctiond. works by quantum tunneling exhibited by gallium arsenide only

27. A tunnel diode is loosely coupled to its cavity in order toa. increase the frequency stability

b. increase the available negative resistancec. facilitate tuningd. allow operation at the highest frequencies

28. The negative resistance in a tunnel diodea. is maximum at the peak point of the characteristicb. is available between the peak and valley pointsc. is maximum at the valley pointd. may be improved by the use of reverse bias

29. The biggest advantage of gallium antimonide over germanium for tunnel-diode use it that former has aa. lower noise

b. higher ion mobilityc. larger voltage swingd. simpler fabrication process

30. Negative resistance is obtained with a Gunn diode because ofa. electron transfer to a less mobile energy levelb. avalanche breakdown with the high voltage gradientc. tunneling across the junctiond. electron domains forming at the junction

31. For Gunn diodes; gallium arsenide is preferred to silicon because theformera. has a suitable empty energy band; which silicon does not have

b. has a higher ion mobilityc. has a lower noise at the highest frequenciesd. is capable of handling higher power densities

32. The biggest disadvantage of the IMPATT diode is itsa. lower efficiency than that of the other microwave diodesb. high noisec. inability to provide pulsed operationd. low power-handling ability



33. The magnetic field is used with a ruby maser toa. provide sharp focusing for the electron beamb. increase the population inversionc. allow room-temperature operationd. provide frequency adjustments

34. The ruby maser has been preferred to the ammonia maser for microwaveamplification; because the former hasa. a much greater bandwidthb. a better frequency stabilityc. a lower noise figured. no need for a circulator

35. Parametric amplifiers and masers are similar to each other in thatboth (indicate false statement)a. must have pumpingb. are extremely low-noise amplifiersc. must be cooled down to a few kelvins

d. generally required cicultators; since they are one-port devices

36. A maser RF amplifier is not really suitable fora. radioastronomyb. satellite communicationsc. radard. troposcatter receiver

37. The ruby laser differs from the ruby maser in that the formera. does not require pumpingb. needs no resonatorc. is an oscillatord. produces much lower powers

38. The output from a laser is monochromatic; this means that it isa. infraredb. polarizedc. narrow-beamd. single-frequency

39. For a given average power; the peak output power of a ruby laser maybe increased bya. using coolingb. using Q spoilingc. increasing the magnetic fieldd. dispensing with the Fabry-Perot resonator

40. Communications lasers are used with optical fiber; rather than in openlinks; toa. ensure that the beam does not spreadb. prevent atmospheric interferencec. prevent interference by other laserd. ensure that people are not blinded by them

41. Indicate the false statement. The advantages of semiconductor lasersover LEDs include



a. monochromatic outputb. higher power outputc. lower costd. ability to be pulsed at higher rates

DIGITAL COMMUNICATIONS

1. Digital signalsa. do not provide a continuous set of valuesb. represent values as discrete stepsc. can utilize decim al or binary systemsd. all of the above

2. The event which marked the start of the modern computer age wasa. design of the ENIAC computerb. development of the Hollerith codec. development of the transistord. development of disk drives for data storage

3. The baud ratea. is always equal to the bit transfer rateb. is equal to twice the bandwidth of an ideal channelc. is not equal to the signaling rate

d. is equal to one-half the bandwidth of an ideal channel

4. The Shannon-Hartley lawa. refers to distortionb. defines bandwidthc. describes signaling ratesd. refers to noise

5. The code which provides for parity checks isa. Baudotb. ASCIIc. EBCDICd. CCITT-2

6. A forward error-correcting code corrects errors bya. requiring partial retransmission of the signalb. requiring retransmission of the entire signalc. requiring no part of the signal to be retransmittedd. using parity to correct the errors in all cases

7. Full duplex operation

a. requires two pairs of cablesb. can transfer data in both directions at oncec. requires modems a t both ends of the circuitd. all of the above

8. The RS-232 interfacea. interconnects data sets and transmission circuitb. uses several different connectorsc. permits custom wiring of signal lines to the connector pins as



desiredd. all of the above

9. Switching systemsa. improve the efficiency of data transferb. are not used in data systemsc. require additional linesd. are limited to small data networks

10. The data transmission rate of a modem is measured ina. bytes per secondb. baud ratec. bits per secondd. megahertz

BROADBAND CUMMUNICATIONS SYSTEMS 1. Broadband long-distance communications were made possible by the adventofa. telegraph cablesb. repeater amplifiersc. HF radid. Geostationary satellites

2. A scheme in which several channels are interleaved and then transmittedtogether is known asa. frequency-division multiplexb. time-division multiplexc. a groupd. a supergroup

3. A basic group Ba. occupies the frequency range from 60 to 108 kHzb. consists of erect channels onlyc. is formed at the group translating equipmentd. consists of five supergroups

4. Time-division multiplexa. can be used with PCM onlyb. combines five groups into a supergroupc. stacks 24 channels in adjacent frequency slotsd. interleaves pulses belonging to different transmissions

5. The number of repeaters along a coaxial cable link depends ona. whether separate tubes are used for the two directions of

transmissionb. the bandwidth of the systemc. the number of coaxial cables in the tubed. the separation of the equalizers

6. A supergroup pilot isa. applied at each multiplexing bayb. used to regulate the gain of individual repeatersc. applied at each adjustable equalizerd. fed in at a GTE



7. Microwave link repeaters are typically 50 km aparta. because of atmospheric attenuationb. because of output tube power limitationsc. because of the Earths curvatured. to ensure that the applied dc voltage is not excessive

8. Microwave links are generally preferred to coaxial cable for televisiontransmission becausea. they have less overall phase distortionb. they are cheaperc. of their greater bandwidthsd. of their relative immunity to impulse noise

9. Armored submarine cable is useda. to protect the cable at great depthsb. to prevent inadvertent ploughing-in of the cablec. for the shallow shore ends of the cabled. to prevent insulation breakdown from the high feed voltages

10. A submarine cable repeater contains; among other equipment;a. a dc power supply and regulatorb. filters for the two directions of transmissionc. multiplexing and demultiplexing equipment

d. pilot injected pilot extract equipment

11. A geostationary satellitea. is motionless in space (except for its spin)b. is not really stationary at all; but orbits the Earth within a 24-hrperiodc. appears stationary over the Earths magnetic poled. is located at a height of 35;800 km to ensure global coverage

12. Indicate the correct statement regarding satellite communications.a. If two earth stations do not face a common satellite; they shouldcommunicate via a double-satellite hop.b. Satellites are allocated so that it is impossible for two earth

stations not to face the same satellitec. Collocated earth stations are used for frequency diversityd. A satellite earth station must have as many receive chains as thereare carriers transmitted to it

13. Satellite used for intercontinental communications are known asa. Comsatb. Domsatc. Marisatd. Intelsat

14. Identical telephone numbers in different parts of a country aredistinguished by theira. language digitsb. access digitsc. area codesd. central office codes



15. Telephone traffic is measureda. with echo cancellersb. by the relative congestionc. in terms of the grade of serviced. in erlangs

16. In order to separate channels in a TDM receiver; it is necessary tousea. AND gatesb. bandpass filtersc. differentiationd. integration

17. To separate channels in an FDM receiver; it is necessary to usea. AND gatesb. bandpass filtersc. differentiationd. integration

18. Higher order TDM levels are obtained bya. dividing pulse widthsb. using the a-lawc. using the µ-law

d. forming supermastergroups

19. Losses in optical fibers can be caused by (indicate the falsestatement)a. impuritiesb. microbendingc. attenuation in the glassd. stepped index operation

20. The 1.55 µm 'window' is not yet in use with fiber optic systemsbecausea. the attenuation is higher than at 0.85 µmb. the attenuation is higher that at 1.3 µm

c. suitable laser devices have not yet been developedd. it does not lend itself to wave

21. Indicate which of the following is not a submarine cablea. TAT-7b. INTELSAT Vc. ATLANTISd. CANTAT 2

22. Indicate which of the following is an American domsat systema. INTELSATb. COMSATc. TELSTAR

d. INMARSAT

RADAR SYSTEMS

1. If the peak transmitted power in a radar system is increased by afactor of 16; the maximum range will be increased by a factora. 2b. 4c. 8



d. 16

2. If the antenna diameter in a radar system is increased by a factor of4; the maximum range will be increased by a factor ofa. v2b. 2c. 4d. 8

3. If the ratio of the antenna diameter to the wavelength in a radarsystem is high this will result in (indicate the false statement)a. large maximum rangeb. good target discriminationc. difficult target acquisitiond. increased capture area

4. The radar cross section of a target (indicate the false statement)a. depends on the frequency usedb. may be reduced by special coating of the targetc. depends on the aspect of a target; if this nonspherical

d. is equal to the actual cross-sectional area for small targets

5. Flat-topped rectangular pulses must be transmitted in radar to(indicate the false statement)a. allow a good minimum rangeb. make the returned echoes easier to distinguish from noisec. prevent frequency changes in the magnetrond. allow accurate range measurements

6. A high PRF will (indicate the false statement)a. make the returned echoes easier to distinguish from noiseb. make target tracking easier with conical scanningc. increase the maximum range

d. have no effect on the range resolution

7. The IF bandwidth of a radar receiver is inversely proportional to thea. pulse widthb. pulse repetition frequencyc. pulse intervald. square root of the peak transmitted power

8. If a return echo arrives after the allocated pulse interval;a. it will interfere with the operation of the transmitterb. the receiver might be overloadedc. it will not be receivedd. the target will appear closer than it really is

9. After a target has been acquired; the best scanning system for trackingisa. noddingb. spiralc. conicald. helical

10. If the target cross section is changing; the best system for accuratetracking is



a. lobe switchingb. sequential lobingc. conical sc anningd. monopulse

11. The biggest disadvantage of CW Doppler radar is thata. it does not give the target velocityb. it does not give the target rangec. a transponder is required at the targetd. it does not give the target position

12. The A scope displaysa. the target position and rangeb. the target range; but not positionc. the target position; but not ranged. neither range nor position; but not only velocity

13. The Doppler effect is used in (indicate the false statement)a. moving-target plotting on the PPIb. the MTI systemc. FM radard. CW radar

14. The coho in MTI radar operates at thea. intermediate frequencyb. transmitted frequencyc. received frequencyd. pulse repetition frequency

15. The function of the quartz delay line in an MTI radar is toa. help in subtracting a complete scan from the previous scanb. match the phase of the coho and the staloc. match the phase of the coho and the output oscillatord. delay a sweep so that the next sweep can be subtracted from it

16. A solution to the 'blind speed' problem is

a. to change the Doppler frequencyb. to vary the PRFc. to use monopulsed. to use MTI

17. Indicate which one of the following applications or advantages ofradar beacons is false:a. Target identificationb. Navigationc. Very significant extension of the maximum ranged. More accurate tracking of enemy targets

18. Compared with other types of radar; phased array radar has the

following advantages (indicate the false statement)a. very fast scanningb. ability to track and scan simultaneouslyc. circuit simplicityd. ability to track many targets simultaneously

PULSE COMMUNICATIONS

1. Indicate which of the following is not a binary codea. Morse



b. Baudotc. CCITT-2d. ARQ

2. To permit the selection of 1 out of 16 equi-probable events; the numberof bits required isa. 2b. log 1610c. 8d. 4

3. A signaling system in which each letter of the alphabet is representedby a different symbol is not used becausea. it would be too difficult for an operator to memorizeb. it is redundantc. noise would introduce too many errorsd. too many pulses per letter are required

4. The Hartley states thata. the maximum rate of information transmission depends on the channelbandwidthb. the maximum rate of information transmission depends on the depth ofmodulation

c. redundancy is essentiald. only binary codes may be used

5. Indicate the false statement. In order to combat noise;a. the channel bandwidth may be increasedb. redundancy may be usedc. the transmitted power may be increasedd. the signaling rate may be reduced

6. The most common modulation system used for telegraphy isa. frequency-shift keying

b. two-tone modulationc. pulse-code modulationd. single-tone modulation

7. Pulse-width modulation system used for telegraphy isa. by differentiating pulse-position modulationb. with a monostablec. by integrating the signald. with a free-running multivibrator

8. Indicate which of the following system is digital.a. Pulse-position modulationb. Pulse-code modulation

c. Pulse-width modulationd. Pulse-frequency modulation

9. Quantizing noise occurs ina. time-division multiplexb. frequency division multiplexc. pulse-code modulationd. pulse-width modulation

10. The modulation system inherently most noise-resistant is



a. SSB; suppressed-carrierb. Frequency modulationc. pulse-position modulationd. pulse-code modulation

11. In order to reduce quantizing noise; one musta. increase the number of standard amplitudesb. send pulses whose sides are more nearly verticalc. use an RF amplifier in the receiverd. increase the number of samples per second

12. The Hartley-Shannon theorem sets a limit on thea. highest frequency that may be sent over a given channel

b. maximum capacity of a channel with a given noise levelc. maximum number of coding levels in a channel with a given noise leveld. maximum number of quantizing levels in a channel of a given bandwidth

13. Indicate which of the following pulse modulation systems is analoga. PCMb. Differential PCMc. PWMd. Delta

14. Companding is useda. to overcome quantizing noise in PCMb. in PCM transmitters; to allow amplitude limited in the receiversc. to protect small signals in PCM from quantizing distortiond. in PCM receivers; to overcome impulse noise

15. The biggest disadvantage of PCM isa. its inability to handle analog signalsb. the high error rate which its quantizing noise introducesc. its incompatibility with TDMd. the large bandwidths that are required for it

TELEVISION FUNDAMENTALS

1. The number of lines per field in the United States TV system isa. 262½b. 525c. 30d. 60

2. The number of frames per second in the United States TV system is

a. 60b. 262½c. 4.5d. 30

3. The number of lines per second in the United States TV system isa. 31;500b. 15;750c. 262½d. 525



4. The channel width in the United States TV system; in MHz; isa. 41.25b. 6c. 4.5d. 3.58

5. Interlacing is used in television toa. produce the illusion of motionb. ensure that all the lines on the screen are scanned; not merely thealternate onesc. simplify the vertical sync pulse traind. avoid flicker

6. The signals sent by the TV transmitter to ensure correct scanning inthe receiver are calleda. syncb. chromac. luminanced. video

7. In the United States color television system; the intercarrierfrequency; in MHz; is

a. 3.58b. 3.57945c. 4.5d. 45.75

8. Indicate which voltages are not found in the output of a normalmonochrome receiver video detector.a. Syncb. Videoc. Sweepd. Sound

9. The carrier transmitted 1.25 MHz above the bottom frequency in the

United States TV channel is thea. sound carrierb. chroma carrierc. intercarrierd. picture carrier

10. In television; 4:3 represents thea. interlace ratiob. maximum horiz ontal deflectionc. aspect ratiod. ratio of the two diagonals

11. Equalizing pulses in TV are sent duringa. horizontal blankingb. vertical blankingc. the serrationsd. the horizontal retrace

12. An odd number of lines per frame forms part of every one of the



worlds TV systems. This isa. done to assist interlaceb. purely an accidentc. to ensure that line and frame frequencies can be obtained from thesame original sourced. done to minimize interference with the chroma subcarrier

13. The function of the serrations in the composite video waveform is toa. equalize the charge in the integrator before the start of verticalretraceb. help vertical synchronizationc. help horizontal synchronizationd. simplify the generation of the vertical sync pulse

14. The width of the vertical sync pulse in the United States TV system isa. 2 1 Hb. 3 Hc. Hd. 0.5 H

15. Indicate which of the following frequencies will not be found in theoutput of a normal TV receiver tuner:a. 4.5 MHzb. 41.25 MHz

c. 45.75 MHzd. 42.17 MHz

16. The video voltage applied to the picture tube of a television receiveris fed ina. between grid and groundb. to the yokec. to the anoded. between grid and cathode

17. The circuit that separates sync pulses from the composite videowaveform isa. the keyed AGC amplifier

b. a clipperc. an integratord. a differentiator

18. The output of the vertical amplifier; applied to the yoke in a TVreceiver; consists ofa. direct currentb. amplified vertical syncc. a sawtooth voltaged. a sawtooth current

19. The HV anode supply for the picture tube of a TV receiver is generatedin the

a. mains transformerb. vertical output stagec. horizontal output staged. horizontal deflection oscillator

20. Another name for the horizontal retrace in a TV receiver is thea. ringingb. burstc. damperd. flyback



21. Indicate which of the following signals is not transmitted in colorTV:a. Yb. Qc. Rd. I

22. The shadow mask in a color picture tube is used toa. reduce x-ray emissionb. ensure that each beam hits only its own dotsc. increase screen brightnessd. provide degaussing for the screen

23. In a TV receiver; the color killera. c uts off the chroma stages during monochrome receptionb. ensures that no color is transmitted to monochrome receiversc. prevents color overloadingd. makes sure that the color burst is not mistaken for sync pulses; bycutting off reception during the back porch

INTRODUCTION TO FIBER OPTIC TECHNOLOGY

1. What is the frequency limit of copper wire?a. approximately 0.5 MHzb. approximately 1.0 MHzc. approximately 40 GHzd. None of the above

2. Approximately what is the frequency limit of the optical fiber?a. 20 GHzb. 1 MHzc. 100 MHz

d. 40 MHz

3. A single fiber can handle as many voice channel asa. a pair of copper conductorsb. a 1500-pair cablec. a 500-pair cabled. a 1000-pair cable

4. An incident ray can be defined asa. a light ray reflected from a flat surfaceb. a light ray directed toward a surfacec. a diffused light rayd. a light ray that happens periodically

5. The term dispersion describes the process ofa. separating light into its component frequenciesb. reflecting light from a smooth surfacec. the process by which light is absorbed by an uneven rough surfaced. light scattering

6. Which of the following terms describes the reason that light isrefracted at different angles?a. Photon energy changes with wavelength



b. Light is refracted as a function of surface smoothnessc. The angle is determined partly by a and bd. The angle is determined by the index of the materials

7. The term critical angle describesa. the point at which light is refractedb. the point at which light becomes invisiblec. the point at which light has gone from the refractive mode to thereflective moded. the point at which light has crossed the boundary layers from oneindex to another

8. The cladding which surrounds the fiber corea. is used to reduce optical interferenceb. is used to protect the fiberc. acts to help guide the light in the cored. ensures that the refractive index remains constant

9. The reflective index number is

a. a number which compares the transparency of a material with that ofairb. a number assigned by the manufacturer to the fiber in questionc. a number which determines the core diameterd. a term for describing core elasticity

10. The terms single mode and multimode are best describes asa. the number of fibers placed into a fiber-optic cableb. the number of voice channels each fiber can supportc. the number of wavelengths each fiber can supportd. the index number

11. The higher the index number

a. the higher the speed of lightb. the lower the speed of lightc. has no effect on the speed of lightd. the shorter the wavelength propagation

12. The three major groups in the optical system area. the components; the data rate and response timeb. the source; the link; and the receiverc. the transmitter; the cable; and the receiverd. the source; the link; and the detector

13. As light is coupled in a multipoint reflective device; the power isreduced by

a. 1.5 dBb. 0.1 dBc. 0.5 dBd. 0.001 dB

14. When connector losses; splice losses; and coupler losses are added;what is the final limiting factor?a. Source powerb. Fiber attenuationc. Connector and splice losses



d. Detector sensitivity

15. The term responsivity as it applies to a light detector is bestdescribed asa. the time required for the signal to go from 10 to 90 percent ofmaximum amplitudeb. the ratio of the diode output current to optical input powerc. the ratio of output current to output powerd. the ratio of output current to input current

16. Loss comparisons between fusion splices and mechanical splices area. 1:10b. 10:1c. 20:1d. 1:20

17. The mechanical splice is best suited fora. quicker installation under ideal conditionsb. minimum attenuation lossesc. field service conditionsd. situations in which cost of equipment is not a factor

18. EMD is best describe by which statement?a. 70 percent of the core diameter and 70% of the fiber NA should befilled with lightb. 70 percent of the fiber diameter and 70% of the cone of acceptanceshould be filled with lightc. 70 percent of input light should be measured at the outputd. 70 percent of the unwanted wavelengths should be attenuated by thefiber

19. Which of the following cables will have the highest launch powercapability?a. 50/125/0.2b. 85/125/0.275c. 62.5/125/0.275d. 100/140/0.3

20. The term power budgeting refers toa. the cost of cables; connectors; equipment; and installationb. the loss of power due to defective componentsc. the total power available minus the attenuation lossesd. the comparative costs of fiber and copper installations

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