KENNEDY 4thEDITIONMULTIPLE CHOICESINTRO TO COMMUNICATIONS SYSTEM1. In a communications system, noise is most likely to affect the signala. at the transmitterb. in the channelc. in the information sourced. at the destination2. Indicate thefalsestatement. Fourier analysis shows that a sawtoothwave 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 withthe harmonic numberd. sinusoidal voltages, some of which are small enough to ignore inpractice3. Indicate thefalsestatement. 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 antennas4. Indicate thefalsestatement. From the transmitter the signaldeterioration because of noise is usuallya. unwanted energyb. predictable in characterc. present in the transmitterd. due to any cause5. Indicate thetruestatement. Most receivers conforms to thea. amplitude-modulated groupb. frequency-modulated groupc. superheterodyne groupd. tuned radio frequency receiver group6. Indicate thefalsestatement. The need for modulation can best beexemplified by the following.a. Antenna lengths will be approximately /4 longb. An antenna in the standard broadcast AM band is 16,000 ftc. All sound is concentrated from 20 Hz to 20 kHzd. A message is composed of unpredictable variations in both amplitudeand frequency 7. Indicate thetruestatement. The process of sending and receivingstarted as early asa. the middle 1930sb. 1850c. the beginning of the twentieth centuryd. the 1840s8. Which of the steps is not included in the process of reception?a. decodingb. encodingc. storaged. interpretation9. The acoustic channel is used for which of the following?a. UHF communicationsb. single-sideband communicationc. television communicationsd. person-to-person voice communications10. 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 NOISE1. One of the following types of noise becomes of great importance at highfrequencies. It is thea. shot noiseb. random noisec. impulse noised. transit-time noise2. Indicate thefalsestatement.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 ismeasured.d. Industrial noise is usually of the impulse type.3. The value of a resistor creating thermal noise is doubled. The noisepower generator is thereforea. halvedb. quadrupledc. doubledd. unchanged4. One of the following isnota useful quantity for comparing the noiseperformance of receivers:a. Input noise voltageb. Equivalent noise resistancec. Noise temperatured. Noise figure5. Indicate the noise whose source is in a category different from that ofthe other three.a. Solar noiseb. Cosmic noisec. Atmospheric noised. Galactic noise6. Indicate thefalsestatement. The square of the thermal noise voltagegenerated 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 transmitterc. externally generated noised. internally generated noise8. Space noise generally covers a wide frequency spectrum, but thestrongest interference occursa. between 8 MHz and 1.43 GHzb. below 20 Mhzc. between 20 to 120 MHzd. above 1.5 GHz9. 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 values10. Which of the following is the most reliable measurement for comparingamplifier noise characteristics?a. signal-to-noise ratiob. noise factorc. shot noised. thermal noise agitation11. Which of the following statements istrue?a. Random noise power is inversely proportional to bandwidthb. Flicker is sometimes calleddemodulation noisec. Noise is mixers is caused by inadequate image frequency rejectiond. A random voltage across a resistance cannot be calculated AMPLITUDE MODULATION1. If the plate supply voltage for a plate-modulated class C amplifier isV, the maximum plate-cathode voltage could be almost as high asa. 4Vb. 3Vc. 2Vd. 1V2. In a low-level AM system, amplifiers following the modulated stage mustbea. linear devicesb. harmonic devicesc. class C amplifiersd. nonlinear devices3. If the carrier of a 100 percent modulated AM wave is suppressed, thepercentage power saving will bea. 50b. 150c. 100d. 66.664. 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 bandwidth5. 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 amplifier6. The modulation index of an AM wave is changed from 0 to 1. Thetransmitted power isa. unchangedb. halvedc. doubledd. increase by 50 percent 7. One of the advantages of the base modulation over collector modulationof a transistor class C amplifier isa. the lower modulating power requiredb. higher power output per transistorc. better efficiencyd. better linearity8. A carrier is simultaneously modulated by two sine waves with modulationindices 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 0.79. 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 forhigh fidelity10. What is the ratio of modulating power to total power at 100 percentmodulation?a. 1:3b. 1:2c. 2:3d. None of the above SINGLE-SIDEBAND TECHNIQUES1. Indicate thefalsestatement regarding the advantages of SSB overdouble 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 strength2. When the modulation index of an AM wave is doubled, the antenna currentis 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 phasecancellation method of obtaining SSB over the filter method isfalse: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 issuppressed better.4. The most commonly used filters in SSB generation area. mechanicalb. RCc. LCd. low-pass5. 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 amplifier6. Indicate in which one of the following only one sideband istransmitted.a. H3Eb. A3Ec. B8Ed. C3F 7. One of the followingcannotbe used to remove the unwanted sideband inSSB. This is thea. filter systemb. phase-shift methodc. third methodd. balanced modulator8. 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 transmission9. To provide two or more voice circuits with the same carrier, it isnecessary to usea. ISBb. carrier insertionc. SSB with pilot carrierd. Lincompex10. Vestigal sideband modulation (C3F) is normally used fora. HF point-to-point communicationsb. monoaural broadcastingc. TV broadcastingd. stereo broadcasting FREQUENCY MODULATION1. In the stabilize reactance modulator AFC system,a. the discriminator must have a fast time constant to preventdemodulationb. the higher the discriminator frequency, the better the oscillatorfrequency stabilityc. the discriminator frequency must not be too low, or the system willfaild. phase modulation is converted into FM by the equalizer circuit2. 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 disappear3. 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 index4. Indicate thefalsestatement 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 unnecessary5. An FM signal with a modulation index mis passed through a frequencyftripler. The wave in the output of the tripler will have a modulationindex ofa. m/3fb. mfc.3mfd. 9mf6. An FM signal with a deviation d is passed through a mixer, and has itsfrequency reduced fivefold. The deviation in the output of the mixer isa. 5db. Indeterminatec. d/5d. d7. 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 equalized9. When the modulating frequency is doubled, the modulation index ishalved, and the modulating voltage remains constant. The modulation systemisa. amplitude modulationb. phase modulationc. frequency modulationd. any of the three10. Indicate which one of the following isnotan 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 required11. 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 modulator12. 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 RADIO RECEIVERS1. Indicate which of the following statements about the advantages of thephase discriminator over the slope detector isfalse:a. Much easier alignmentb. Better linearityc. Greater limitingd. Fewer tuned circuits2. Show which of the following statements about the amplitude limiter isuntrue:a. The circuit is always biased in class C, by virtue of the leak-typebias.b. When the input increases past the threshold of the limiting, the gaindecreases to keep the output constant.c. The output must be tunedd. Leak-type bias must be used3. 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 produced4. 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 frequency5. To prevent overloading of the IF amplifier in a receiver, one shouldusea. squelchb. variable sensitivityc. variable selectivityd. double conversion6. A superheterodyne receiver with an IF of 450 kHz is tuned to a signalat 1200 kHz. The image frequency isa. 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 phasediscriminatord. the circuit is the same as in a discriminator, except that the diodesare reversed8. The typical squelch circuit cuts offa. 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 minimum9. Indicate thefalsestatement 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 fading10. 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 frequency11. 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 problemb. increase the frequency stability of the synthesizerc. reduce the number of decadesd. reduce the number of crystals required12. Indicate which of the following circuits couldnotdemodulate 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 receiver14. Indicate thefalsestatement. 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. instability15. 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 tuned16. 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 frequency17. A receiver has poor IF selectivity. It will therefore also have poora. blockingb. double-spottingc. diversion receptiond. sensitivity18. Three-point tracking is achieved witha. variable selectivityb. the padder capacitorc. double spottingd. double conversion19. 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 (indicatefalsestatement)a. image frequency rejection is very goodb. the local oscillator need not be extremely stablec. the selectivity will be poord. tracking will be improved21. 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 response22. One of the followingcannotbe used to demodulate SSB:a. Product detectorb. Diode Balance modulatorc. Bipolar transistor balanced modulatord. Complete phase-shift generator23. Indicate thefalsestatement. Noting that no carrier is transmitterwith J3E, we see thata. the receiver cannot use a phase comparator for AFCb. adjacent-channel rejection is more difficultc. production of AGC is a rather complicated processd. the transmission is not compatible with A3E24. 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 burnout25. An AM receiver uses a diode detector for demodulation. This enables itsatisfactorily to receivea. single-sideband, suppressed-carrierb. single-sideband, reduced-carrierc. ISBd. Single-sideband, full-carrier TRANSMISSION LINES1. Indicate thefalsestatement. The SWR on a transmission line isinfinity; the line is terminated ina. a short circuitb. a complex impedancec. an open circuitd. a pure reactance2. A (75-j50)- is connected to a coaxial transmission line of Z= 75 ,Oat 10 GHz. Thebestmethod 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 load3. 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 air4. Impedance inversion may be obtained witha. a short-circuited stubb. an open-circuited stubc. a quarter-wave lined. a half-wave line5. Short-circuited stubs are preferred to open-circuited stubs because thelatter area. more difficult to make an connectb. made of a transmission line with a different characteristic impedancec. liable to radiated. incapable of giving a full range of reactances6. For transmission-line load matching over a range of frequencies, it isbest to use aa. balunb. broadband directional couplerc. double stubd. single stub of adjustable position 7. The main disadvantage of the two-hole directional coupler isa. low directional couplingb. poor directivityc. high SWRd. narrow bandwidth8. To couple a coaxial line to a parallel-wire line, it is best to use aa. slotted lineb. balunc. directional couplerd. quarter-wave transformer9. Indicate the three types of transmission line energy losses.a.IR,R, and temperature2Lb. Radiation,IR, and dielectric heating2c. Dielectric separation, insulation breakdown, and radiationd. Conductor heating, dielectric heating, and radiation resistance.10. Indicate thetruestatement 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 WAVES1. Indicate which one of the following terms applies to troposcatterpropagation:a. SIDsb. Fadingc. Atmospheric stormsd. Faraday rotation2. VLF waves are used for some type of services becausea. of the low powers requiredb. the transmitting antennas are of convenient sizec. they are very reliabled. the penetrate the ionosphere easily3. Indicate which of the following frequenciescannotbe used for reliablebeyond-the-horizon terrestrial communications without repeaters:a. 20 kHzb. 15 MHzc. 900 MHzd. 12 GHz4. High-frequency waves area. absorbed by theFlayer2b. reflected by theDlayerc. capable of use for long-distance communications on the moond. affected by the solar cycle5. 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 frequency6. 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 atmosphere8. Frequencies in the UHF range normally propagate by means ofa. ground wavesb. sky wavesc. surface wavesd. space waves9. Tropospheric scatter is used with frequencies in the following range:a. HFb. VHFc. UHFd. VLF10. The ground wave eventually disappears, as one moves away from thetransmitter, because ofa. interference from the sky waveb. loss of line-of-sight conditionsc. maximumsingle-hop distance limitationd. tilting11. In electromagnetic waves, polarizationa. is caused by reflectionb. is due to the transverse nature of the wavesc. results from the longitudinal nature of the wavesd. is always vertical in an isotropic medium12. As electromagnetic waves travel in free space, only one of thefollowing can happen to them:a. absorptionb. attenuationc. refractiond. reflection13. 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 plane15. Diffraction of electromagnetic wavesa. is caused by reflections from the groundb. arises only with spherical wavefrontsc. will occur when the waves pass through a large slotd. may occur around the edge of a sharp obstacle16. When microwave signals follow the curvature of the earth, this isknown asa. the Faraday effectb. ductingc. tropospheric scatterd. ionospheric reflection17. Helical antennas are often used for satellite tracking at VHF becauseofa. troposcatterb. superrefractionc. ionospheric refractiond. the Faraday effect ANTENNAS1. 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 polarized2. One of the following consists of nonresonant antennas:a. The rhombic antennab. The folded dipolec. The end-fire arrayd. The broadside array3. One of the following is very useful as a multiband HF receivingantenna. This is the:a. conical hornb. folded dipolec. log periodicd. square loop4. Which of the following antennas is best excited from a waveguide?a. Biconicalb. Hornc. Helicald. Discone5. Indicate which of the following reasons for using a counterpoise withantenna isfalse:a. Impossibility of a good ground connectionb. Protection of personnel working undergroundc. Provision of an earth for the antennad. Rockiness of the ground6. One of the following isnota 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 oscillator7. Indicate the antenna that isnotwidebandL:a. Disconeb. Folded Dipolec. Helicald. Marconi 8. Indicate which one of the following reasons for the use of a groundscreen with antennas isfalse:a. Impossibility of a good ground connectionb. Provision of an earth for the antennac. Protection of personnel working underneathd. Improvement of the radiation pattern of the antenna9. Which one of the following terms doesnotapply to the Yagi-Uda array?a. Good bandwidthb. Parasitic elementsc. Folded dipoled. High gain10. An antenna that is currently polarized us thea. helicalb. small circular loopc. parabolic reflectord. Yagi-Uda11. The standard reference antenna for the directive gain is thea. infinitesimal dipoleb. isotropic antennac. elementary doubletd. half-wave dipole12. Top loading is sometimes used with an antenna in order to increase itsa. effective heightb. bandwidthc. beamwidthd. input capacitance13. 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 point14. 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 ratio16. The discone antenna isa. useful direction-finding antennab. used as a radar receiving antennac. circularly polarized like other circular antennasd. useful as UHF receiving antennas17. One of the following isnotan omnidirectional antenna:a. Half-wave dipoleb. Log-periodicc. Disconed. Marconi WAVEGUIDES, RESONATORS AND COMPONENTS1. 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 waveguide2. 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 lowerfrequenciesd. they would be too bulky at lower frequencies3. 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 velocity4. 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 asimpedance matchingandstanding-wave ratiocannot beapplied to waveguides5. Compared with equivalent transmission lines, 3-GHz waveguides (indicatefalsestatement)a. are less lossyb. can carry higher 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-electromagnetic7. 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 propagation8. 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 velocityc. group velocityd. phase velocity9. Indicate thefalsestatement. 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 infinite10. 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 isa. TE1,1b. TE1,0c. TM2,2d. TE2,011. The dominant mode of propagation is preferred with rectangularwaveguides because (indicatefalsestatement)a. it leads to the smallest waveguide dimensionsb. 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 system13. In order to couple two generators to a waveguide system withoutcoupling them to each other, on couldnotuse aa. at-racerb.E-plane Tc. hybrid ringd. magic T14. Which of the following waveguides tuning components isnoteasilyadjustable?a. Screwb. Stubc. Irisd. Plunger15. A piston attenuator is aa. vane attenuatorb. waveguide below cutoffc. mode filterd. flap attenuator16. Cylindrical cavity resonators are not used with klystrons because theyhavea. aQthat is too lowb. a shape whose resonant frequency is too difficult to calculatec. harmonically related resonant frequenciesd. too heavy losses17. 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 system18. 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 (indicatefalseanswer)a. circulatorb. isolatorc. garnetd. phase shifter20. The maximum power that may be handled by a ferrite component islimited by thea. Curie temperatureb. Saturation magnetizationc. line widthd. gyromagnetic resonance21. 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 switch22. 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 radar23. For some applications, circular waveguides may be preferred torectangular ones because ofa. the smaller crosssection needed at any frequencyb. lower attenuationc. freedom from spurious modesd. rotation of polarization24. Indicate which of the following cannot be followed by the wordwaveguide:a. Ellipticalb. Flexiblec. Coaxiald. Ridged 25. In order to reduce cross-sectional dimensions, the waveguide to use isa. circularb. ridgedc. rectangulard. flexible26. For low attenuation, the best transmission medium isa. flexible waveguideb. ridged waveguidec. rectangular waveguided. coaxial line MICROWAVE TUBES AND CIRCUITS1. A microwave tube amplifier uses an axial magnetic field and a radialelectric field. This is thea. reflex klystronb. coaxial magnetronc. traveling-wave magnetrond. CFA2. One of the following is unlikely to be used as a pulsed device. It isthea. multicavity klystronb. BWOc. CFAd. TWT3. 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 small4. Indicate thefalsestatement. 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 larger5. The multicavity klystrona. is not a good low-level amplifier because of noiseb. has a higher repeller voltage to ensure a rapid transit timec. is not suitable for pulsed operationd. needs a long transit time through the buncher cavity to ensurecurrent modulation6. Indicate thefalsestatement. 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 ita. is more efficientb. has a greater bandwidthc. has a higher number of modesd. produces a higher output power8. The transit time in the repeller space of a reflex klystron must ben+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 electrons9. The cavity magnetron uses strapping toa. prevent mode jumpingb. prevent cathode back-heatingc. ensure bunchingd. improve the phase-focusing effect10. 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 cathode11. To avoid difficulties with strapping at high frequencies, the type ofcavity structure used in the magnetron is tha. hole-and-slotb. slotc. vaned. rising sun12. 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 figure13. 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 electromagnetd. allow coupled-cavity operation at the highest frequencies15. 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 bandwidthc. more broadbandd. less noisy16. A magnetron whose oscillating frequency is electronically adjustableover a wide range is called aa. coaxial magnetronb. dither-tuned magnetronc. frequency-agile magnetrond. VTM17. Indicate which of the following isnota TWT slow-wave structure:a. Periodic-permanent magnetb. Coupled cavityc. Helixd. Ring-bar18. The glass tube of a TWT may be coated with aquadag toa. help focusingb. provide attenuationc. improve bunchingd. increase gain19. A backward-wave oscillator is based on thea. rising-sun magnetronb. crossed-field amplifierc. coaxial magnetrond. traveling-wave tube SEMICONDUCTOR MICROWAVE DEVICES AND CIRCUITS1. A parametric amplifier must be cooleda. because parametric amplification generates a lot of heatb. to increase bandwidthc. because it cannot operate at roomtemperatured. to improve the noise performance2. 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 performance3. 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 manufacture4. The transmission system using two ground plane isa. microstripb. elliptical waveguidec. parallel-wire lined. stripline5. Indicate thefalsestatement. An advantage of stripline over wveguideis itsa. smaller bulkb. greater bandwidthc. higher power-handling capabilityd. greater compatibility with solid-state devices6. Indicate thefalsestatement. An advantage of stripline over microstripis itsa. easier integration with semiconductor devicesb. lower tendency to radiatec. higher isolation between adjacent circuitsd. higher Q7. Surface acoustics waves propagate ina. gallium arsenideb. indium phosphidec. striplined. quartz crystal 8. SAW devices may be used asa. transmission media like striplineb. filtersc. UHF amplifiersd. Oscillators at millimeter frequencies9. Indicate thefalsestatement. 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 gains10. 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 diode11. 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 harmonics12. Indicate which of the following diodes will produce the highest pulsedpower output:a. Varatorb. Gunnc. Schottkybarrierd. RIMPATT13. Indicate which of the following diodes does not use negativeresistnace in its operation:a. Backwardb. Gunnc. IMPATTd. Tunnel 14. One of the following isnotused as a microwave mixer or detector:a. Crystal diodeb. Schottky-barrier diodec. Backward dioded. PIN diode15. One of the following microwave diodes is suitable for very low-poweroscillators only:a. Tunnelb. avalanchec. Gunnd. IMPATT16. The transferred-electron bulk effect occurs ina. germaniumb. gallium arsenidec. silicond. metal semiconductor junctions17. 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 tounityd. beta of the transistor falls to unity18. For a microwave transistor to operate at the highest frequencies, the(indicate thefalseanswer)a. collector voltage must be largeb. collector current must be highc. base should be thind. emitter area must be large19. A varactor diode may be useful at microwave frequencies (indicate thefalseanswer)a. for electronic tuningb. for frequency multiplicationc. 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 needed21. 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-converter22. A nondegenerate parametric amplifier has an input frequencyfand aipump frequencyf. Then idler frequency ispa.fib. 2fic.ffipd.f-fpi23. Traveling-wave parametric amplifiers are used toa. provide a greater gainb. reduce the number of varactor diodes requiredc. avoid the need for coolingd. provide greater bandwidth24. 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 pumping25. 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 only27. A tunnel diode is loosely coupled to its cavity in order toa. increase the frequency stabilityb. increase the available negative resistancec. facilitate tuningd. allow operation at the highest frequencies28. 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 bias29. The biggest advantage of gallium antimonide over germanium for tunnel-diode use it that former has aa. lower noiseb. higher ion mobilityc. larger voltage swingd. simpler fabrication process30. 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 junction31. For Gunn diodes, gallium arsenide is preferred to silicon because theformera. has a suitable empty energy band, which silicon does not haveb. has a higher ion mobilityc. has a lower noise at the highest frequenciesd. is capable of handling higher power densities32. 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 adjustments34. 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 circulator35. Parametric amplifiers and masers are similar to each other in thatboth (indicatefalsestatement)a. must have pumpingb. are extremely low-noise amplifiersc. must be cooled down to a few kelvinsd. generally required cicultators, since they are one-port devices36. A maser RF amplifier is not really suitable fora. radioastronomyb. satellite communicationsc. radard. troposcatter receiver37. 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 powers38. The output from a laser is monochromatic; this means that it isa. infraredb. polarizedc. narrow-beamd. single-frequency39. For a given average power, thepeakoutput power of a ruby laser maybe increased bya. using coolingb. usingQspoilingc. 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 them41. Indicate thefalsestatement. The advantages of semiconductor lasersover LEDs includea. monochromatic outputb. higher power outputc. lower costd. ability to be pulsed at higher rates DIGITAL COMMUNICATIONS1. Digital signalsa. do not provide a continuous set of valuesb. represent values as discrete stepsc. can utilize decimal or binary systemsd. all of the above2. 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 storage3. 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 rated. is equal to one-half the bandwidth of an ideal channel4. The Shannon-Hartley lawa. refers to distortionb. defines bandwidthc. describes signaling ratesd. refers to noise5. The code which provides for parity checks isa. Baudotb. ASCIIc. EBCDICd. CCITT-26. 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 cases7. Full duplex operationa. requires two pairs of cablesb. can transfer data in both directions at oncec. requires modems at 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 asdesiredd. all of the above9. Switching systemsa. improve the efficiency of data transferb. are not used in data systemsc. require additional linesd. are limited to small data networks10. The data transmission rate of a modem is measured ina. bytes per secondb. baud ratec. bits per secondd. megahertz BROADBAND CUMMUNICATIONS SYSTEMS1. Broadband long-distance communications were made possible by the adventofa. telegraph cablesb. repeater amplifiersc. HF radid. Geostationary satellites2. A scheme in which several channels are interleaved and then transmittedtogether is known asa. frequency-division multiplexb. time-division multiplexc. a groupd. a supergroup3. A basic groupBa. occupies the frequency range from 60 to 108 kHzb. consists of erect channels onlyc. is formed at the group translating equipmentd. consists of five supergroups4. 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 transmissions5. The number of repeaters along a coaxial cable link depends ona. whether separate tubes are used for the two directions oftransmissionb. the bandwidth of the systemc. the number of coaxial cables in the tubed. the separation of the equalizers6. 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 excessive8. 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 noise9. 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 voltages10. 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 equipmentd. pilot injected pilot extract equipment11. 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 coverage12. 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 earthstations 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. Intelsat14. Identical telephone numbers in different parts of a country aredistinguished by theira. language digitsb. access digitsc. area codesd. central office codes15. Telephone traffic is measureda. with echo cancellersb. by the relative congestionc. in terms of the grade of serviced. in erlangs16. In order to separate channels in aTDMreceiver, it is necessary tousea. AND gatesb. bandpass filtersc. differentiationd. integration17. To separate channels in an FDM receiver, it is necessary to usea. AND gatesb. bandpass filtersc. differentiationd. integration18. Higher order TDM levels are obtained bya. dividing pulse widthsb. using the a-lawc. using the -lawd. forming supermastergroups19. Losses in optical fibers can be caused by (indicate thefalsestatement)a. impuritiesb. microbendingc. attenuation in the glassd. stepped index operation 20. The 1.55 m window is not yet in use with fiber optic systemsbecausea. the attenuation is higher than at 0.85 mb. the attenuation is higher that at 1.3 mc. suitable laser devices have notyet been developedd. it does not lend itself to wave21. Indicate which of the following isnota submarine cablea. TAT-7b. INTELSAT Vc. ATLANTISd. CANTAT 222. Indicate which of the following is an American domsat systema. INTELSATb. COMSATc. TELSTARd. INMARSAT RADAR SYSTEMS1. 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. 8d. 162. 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. 83. If the ratio of the antenna diameter to the wavelength in a radarsystem is high this will result in (indicate thefalsestatement)a. large maximum rangeb. good target discriminationc. difficult target acquisitiond. increased capture area4. The radar cross section of a target (indicate thefalsestatement)a. depends on the frequency usedb. may be reduced by special coating of the targetc. depends on the aspect of a target, if this nonsphericald. is equal to the actual cross-sectional area for small targets5. Flat-topped rectangular pulses must be transmitted in radar to(indicate thefalsestatement)a. allow a good minimum rangeb. make the returned echoes easier to distinguish from noisec. prevent frequency changes in the magnetrond. allow accurate range measurements6. A high PRF will (indicate thefalsestatement)a. make the returned echoes easier to distinguish from noiseb. make target tracking easier with conical scanningc. increase the maximum ranged. 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 power8. 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 is9. After a target has been acquired, the best scanning system for trackingisa. noddingb. spiralc. conicald. helical10. If the target cross section is changing, the best system for accuratetracking isa. lobe switchingb. sequential lobingc. conical scanningd. monopulse11. 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 position12. 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 velocity13. The Doppler effect is used in (indicate thefalsestatement)a. moving-target plotting on the PPIb. the MTI systemc. FM radard. CW radar 14. Thecohoin MTI radar operates at thea. intermediate frequencyb. transmitted frequencyc. received frequencyd. pulse repetition frequency15. 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 it16. A solution to the blind speed problem isa. to change the Doppler frequencyb. to vary the PRFc. to use monopulsed. to use MTI17. Indicate which one of the following applications or advantages ofradar beacons isfalse:a. Target identificationb. Navigationc. Very significant extension of the maximum ranged. More accurate tracking of enemy targets18. Compared with other types of radar, phased array radar has thefollowing advantages (indicate thefalsestatement)a. very fast scanningb. ability to track and scan simultaneouslyc. circuit simplicityd. ability to track many targets simultaneously PULSE COMMUNICATIONS1. Indicate which of the following isnota binary codea. Morseb. Baudotc. CCITT-2d. ARQ2. To permit the selection of 1 out of 16 equi-probable events, the numberof bits required isa. 2b. log1610c. 8d. 43. 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 required4. The Hartley states thata. the maximum rate of information transmission depends on the channelbandwidthb. the maximum rate of information transmission depends on the depth ofmodulationc. redundancy is essentiald. only binary codes may be used5. Indicate thefalsestatement. 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 reduced6. The most common modulation system used for telegraphy isa. frequency-shift keyingb. 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 multivibrator8. Indicate which of the following system is digital.a. Pulse-position modulationb. Pulse-code modulationc. Pulse-width modulationd. Pulse-frequency modulation9. Quantizing noise occurs ina. time-division multiplexb. frequency division multiplexc. pulse-code modulationd. pulse-width modulation10. The modulation system inherently most noise-resistant isa. SSB, suppressed-carrierb. Frequency modulationc. pulse-position modulationd. pulse-code modulation11. 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 second12. The Hartley-Shannon theorem sets a limit on thea. highest frequency that may be sent over a given channelb. 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 bandwidth13. 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 noise15. 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 FUNDAMENTALS1. The number of lines per field in the United States TV system isa. 262b. 525c. 30d. 602. The number of frames per second in the United States TV system isa. 60b. 262c. 4.5d.303. The number of lines per second in the United States TV system isa. 31,500b. 15,750c. 262d. 5254. The channel width in the United States TV system, in MHz, isa. 41.25b. 6c. 4.5d. 3.585. 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 flicker6. 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, theintercarrierfrequency, in MHz, isa. 3.58b. 3.57945c. 4.5d. 45.758. Indicate which voltages arenotfound in the output of a normalmonochrome receiver video detector.a. Syncb. Videoc. Sweepd. Sound9. The carrier transmitted 1.25 MHz above the bottom frequency in theUnited States TV channel is thea. sound carrierb. chroma carrierc. intercarrierd. picture carrier10. In television, 4:3 represents thea. interlace ratiob. maximum horizontal deflectionc. aspect ratiod. ratio of the two diagonals11. Equalizing pulses in TV are sent duringa. horizontal blankingb. vertical blankingc. the serrationsd. the horizontal retrace12. An odd number of lines per frame forms part of every one of theworlds 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 theserrationsin 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 pulse14. The width of the vertical sync pulse in the United States TV system isa. 21Hb. 3Hc.Hd. 0.5H15. Indicate which of the following frequencies willnotbe found in theoutput of a normal TV receiver tuner:a. 4.5 MHzb. 41.25 MHzc. 45.75 MHzd. 42.17 MHz16. 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 cathode17. The circuit that separates sync pulses from the composite videowaveform isa. the keyed AGC amplifierb. a clipperc. an integratord. a differentiator18. 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 thea. mains transformerb. vertical output stagec. horizontal output staged. horizontal deflection oscillator20. Another name for the horizontal retrace in a TV receiver is thea. ringingb. burstc. damperd. flyback21. Indicate which of the following signals isnottransmitted in colorTV:a.Yb.Qc.Rd.I22. Theshadow maskin 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 screen23. In a TV receiver, thecolor killera.cuts 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 TECHNOLOGY1. What is the frequency limit of copper wire?a. approximately 0.5 MHzb. approximately 1.0 MHzc. approximately 40 GHzd. None of the above2. Approximately what is the frequency limit of the optical fiber?a. 20 GHzb. 1 MHzc. 100 MHzd. 40 MHz3. 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 cable4. 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 periodically5. The termdispersiondescribes 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 scattering6. Which of the following terms describes the reason that light isrefracted at different angles?a. Photon energy changes with wavelengthb. Light is refracted as a function of surface smoothnessc. The angle is determined partly byaandbd. 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 another8. 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 constant9. The reflective index number isa. 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 elasticity10. The termssingle modeandmultimodeare 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 number11. The higher the index numbera. the higher the speed of lightb. the lower the speed of lightc. has no effect on the speed of lightd. the shorter the wavelength propagation12. 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 detector13. As light is coupled in a multipoint reflective device, the power isreduced bya. 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 lossesd. Detector sensitivity15. The termresponsivityas 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 current16. Loss comparisons between fusion splices and mechanical splices area. 1:10b. 10:1c. 20:1d. 1:2017. 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 factor18. 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 thefiber19. 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 termpower budgetingrefers 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