Frenzel Full

8/11/2019 Frenzel Full

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CHAPTER 1

INTRODUCTION TO

ELECTRONIC

COMMUNICATIONS

1. Communication is the process

ofa. keeping in touchb. broadcastingc. exchanging informationd. entertainment by

electronics

2. Two key barriers to humancommunication are

a. distance

b. costc. ignoranced. language

3. Electronic communicationswas discovered in which century?

a. sixteenthb. eighteenthc. nineteenthd. twentieth

4. Which of the following is not amajor communications medium?

a. free spaceb. waterc. wiresd. fiber optic cable

5. Random interference totransmitted signals is called

a. adjacent channel overlapb. cross talkc. garbage-in-garbage-outd. noise

6. The communications mediumcauses the signal to be

a. amplifiedb. modulated

c. attenuatedd. interfered with

7. Which of the following is not asource of noise?

a. another communications

signal

b. atmospheric effectsc. manufactured electrical

systemsd. thermal agitation in

electronic components

8. One-way communications iscalled

a. half duplex

b. full duplexc. monocommd. simplex

9. Simultaneous two-waycommunications is called

a. half duplexb. full duplexc. bicommd. simplex

10. The original electricalinformation signal to be transmittedis called the

a. modulating signalb. carrierc. baseband signald. source signal

11. The process of modifying a

high-frequency carrier with theinformation to be transmitted iscalled

a. multiplexingb. telemetryc. mixingd. modulation


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12. The process of transmittingtwo or more information signalssimultaneously over the samechannel is called

a. multiplexingb. telemetry

c. mixingd. modulation

13. Continuous voice or videosignals are referred to as being

a. basebandb. analogc. digitald. continuous waves

14. Recovering information from acarrier is known as

a. demultiplexingb. modulationc. detectiond. carrier recovery

15. Transmission of graphicalinformation over the telephonenetwork is accomplished by

a. televisionb. CATVc. videotextd. facsimile

16. Measuring physical conditionsat some remote location andtransmitting this data for analysis isthe process of

a. telemetry

b. instrumentationc. modulationd. multiplexing

17. Receiving electromagneticemissions from stars is called

a. astrologyb. optical astronomyc. radio astronomy

d. space surveillance

18. A personal communicationshobby for individuals is

a. ham radiob. electronic bulletin board

c. CB radiod. cellular radio

19. Radar is based upona. microwavesb. a water mediumc. the directional nature of

radio signalsd. reflected radio signals

20. A frequency of 27 MHz has awavelength of approximately

a. 11 mb. 27 mc. 30 md. 81 m

21. Radio signals are made up ofa. voltages and currentsb. electric and magnetic

fieldsc. electrons and protonsd. noise and data

22. The voice frequency range isa. 30 to 300 Hzb. 300 to 3000 Hzc. 20 Hz to 20 kHzd. 0 Hz to 15 kHz

23. Another name for signals in theHF range isa. microwavesb. RF wavesc. shortwavesd. millimeter waves

24. Television broadcasting occursin which ranges?


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a. HFb. EHFc. VHFd. UHF

25. Electromagnetic waves

produced primarily by heat arecalled

a. infrared raysb. microwavesc. shortwavesd. x-rays

26. A micron isa. one-millionth of a footb. one-millionth of a meter

c. one-thousandth of a meterd. one ten-thousandth of an

inch

27. The frequency range ofinfrared rays is approximately

a. 30 to 300 GHzb. 4000 to 8000 Ac. 1000 to 10,000 A

d. 0.7 to 100 m

28. The approximate wavelengthof red light is

a. 1000 mb. 7000 Ac. 3500 Ad. 4000 A

29. Which of the following is notused for communications?

a. x-raysb. millimeter wavesc. infraredd. microwaves

30. A signal occupies the spectrumspace from 1.115 to 1.122 GHz.The bandwidth is

a. 0.007 MHzb. 7 MHzc. 237 MHzd. 700 MHz

31. In the United States, the

electromagnetic spectrum isregulated and managed by

a. business and industryb. ITUc. FCCd. The United Nations

32. For a given bandwidth signal,more channel space is availablefor signals in the range of

a. VHFb. UHFc. SHFd. EHF

CHAPTER 2

AMPLITUDE MODULATION AND

SINGLE-SIDEBAND

MODULATION

1. Having an information signalchange some characteristic of acarrier signal is called

e. multiplexingf. modulationg. duplexingh. linear mixing

2. Which of the following is not

true about AM?e. The carrier amplitudevaries.

f. The carrier frequencyremains constant.

g. The carrier frequencychanges.


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h. The information signalamplitude changes thecarrier amplitude.

3. The opposite of modulation ise. reverse modulation

f. downward modulationg. unmodulationh. demodulation

4. The circuit used to producemodulation is called a

e. modulatorf. demodulatorg. variable gain amplifierh. multiplexer

5. A modulator circuit performswhat mathematical operation on itstwo inputs?

e. additionf. multiplicationg. divisionh. square root

6. The ratio of the peakmodulating signal voltage to the

peak carrier voltage is referred toas

e. the voltage ratiof. decibelsg. the modulation indexh. the mix factor

7. If m is greater than 1, whathappens?

e. normal operation

f. carrier drops to zerog. carrier frequency shiftsh. information signal is

distorted

8. For ideal AM, which of thefollowing is true?

e. m = 0f. m = 1

g. m < 1h. m > 1

9. The outline of the peaks of acarrier has the shape of themodulating signal and is called the

e. tracef. waveshapeg. envelopeh. carrier variation

10. Overmodulation occurs whene. Vm> Vcf. Vm< Vcg. Vm= Vch. Vm= Vc= 0

11. The values of Vmaxand Vminasread from an AM wave on anoscilloscope are 2.8 and 0.3. Thepercentage of modulation is

e. 10.7 percentf. 41.4 percentg. 80.6 percenth. 93.3 percent

12. The new signals produced bymodulation are called

e. spurious emissionsf. harmonicsg. intermodulation productsh. sidebands

13. A carrier of 880 kHz ismodulated by a 3.5 kHz sine wave.The LSB and USB are,

respectively,e. 873 and 887 kHzf. 876.5 and 883.5 kHzg. 883.5 and 876.5 kHzh. 887 and 873 kHz

14. A display of signal amplitudeversus frequency is called the

e. time domain


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f. frequency spectrumg. amplitude spectrumh. frequency domain

15. Most of the power in an AMsignal is in the

e. carrierf. upper sidebandg. lower sidebandh. modulating signal

16. An AM signal has a carrierpower of 5 W. The percentage ofmodulation is 80 percent. Thetotal sideband power is

e. 0.8 W

f. 1.6 Wg. 2.5 Wh. 4.0 W

17. For 100 percent modulation,what percentage of power is ineach sideband?

e. 25 percentf. 33.3 percent

g. 50 percenth. 100 percent

18. An AM transmitter has apercentage of modulation of 88.The carrier power is 440 W. Thepower in one sideband is

e. 85 Wf. 110 Wg. 170 W

h. 610 W

19. An AM transmitter antennacurrent is measured with nomodulation and found to be 2.6amperes. With modulation, thecurrent rises to 2.9 amperes. Thepercentage of modulation

e. 35 percent

f. 70 percentg. 42 percenth. 89 percent

20. What is the carrier power in theproblem above if the antenna

resistance is 75 ohms?e. 195 Wf. 631 Wg. 507 Wh. 792 W

21. In an AM signal, thetransmitted information iscontained within the

e. carrier

f. modulating signalg. sidebandsh. envelope

22. An AM signal without thecarrier is called a(n)

e. SSBf. Vestigial sidebandg. FM signalh. DSB

23. What is the minimum AMsignal needed to transmitinformation?

e. carrier plus sidebandsf. carrier onlyg. one sidebandh. both sidebands

24. The main advantage of SSB

over standard AM or DSB ise. Less spectrum space isused

f. Simpler equipment is usedg. Less power is consumedh. A higher modulation

percentage


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25. In SSB, which sideband is thebest to use?

e. Upperf. Lowerg. Neitherh. Depends upon the use

26. The typical audio modulatingfrequency range used in radio andtelephone communications is

e. 50 Hz to 5 kHzf. 50 Hz to 15 kHzg. 100 Hz to 10 kHzh. 300 Hz to 3 kHz

27. An AM signal with a maximum

modulating signal frequency of 4.5kHz has a total bandwidth of

e. 4.5 kHzf. 6.75 kHzg. 9 kHzh. 18 kHz

28. Distortion of the modulatingsignal produces harmonics whichcause an increase in the signal

e. carrier powerf. bandwidthg. sideband powerh. envelope voltage

29. The process of translating asignal, with or without modulation,to a higher or lower frequency forprocessing is called

e. frequency multiplication

f. frequency divisiong. frequency shifth. frequency conversion

30. Frequency translation iscarried out by a circuit called a

e. translatorf. converterg. balanced modulator

h. local oscillator

31. An input signal of 1.8 MHz ismixed with a local oscillator of 5MHz. A filter selects the differencesignal. The output is

e. 1.8 MHzf. 3.2 MHzg. 5 MHzh. 6.8 MHz

32. The output of an SSBtransmitter with a 3.85 MHz carrierand a 1.5 kHz sine wavemodulating tone is

e. a 3.8485-MHz sine wave

f. a 3.85-MHz sine waveg. 3.85-, 3.845-, and 3.8515-

MHz sine wavesh. 3848.5- and 3851.5 MHz

sine waves

33. An SSB transmitter produces a400 V peak-to-peak signal across

a 52 antenna load. The PEP

output isa. 192.2 Wb. 384.5 Wc. 769.2 Wd. 3077 W

34. The output power of an SSBtransmitter is usually expressed interms of

a. average power

b. RMS powerc. peak-to-peak powerd. peak envelope power

35. An SSB transmitter has a PEPrating of 1 kW. The averageoutput power is in the range of

a. 150 to 450 Wb. 100 to 300 W


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c. 250 to 333 Wd. 3 to 4 kW

CHAPTER 3

AMPLITUDE MODULATION

CIRCUITS

1. Amplitude modulation is thesame as

i. Linear mixingj. Analog multiplicationk. Signal summationl. Multiplexing

2. In a diode modulator, thenegative half of the AM wave issupplied by a(n)

i. Tuned circuitj. Transformerk. Capacitorl. Inductor

3. Amplitude modulation can beproduced by

i. having the carrier vary aresistance

j. having the modulating

signal vary a capacitancek. varying the carrier

frequencyl. varying the gain of an

amplifier

4. Amplitude modulators that varythe carrier amplitude with themodulating signal by passing itthrough an attenuator work on the

principle ofi. rectificationj. resonancek. variable resistancel. absorption

5. The component used toproduce AM at very highfrequencies is a

i. varactorj. thermistork. cavity resonatorl. PIN diode

6. Amplitude modulation

generated at a very low voltage orpower amplitude is known as

i. high-level modulationj. low-level modulationk. collector modulationl. minimum modulation

7. A collector modulator has asupply voltage of 48 V. The peak-to-peak amplitude of the

modulating signal for 100 percentmodulation is

i. 24 Vj. 48 Vk. 96 Vl. 120 V

8. A collector-modulatedtransmitter has a supply voltage of24 V and a collector current of 0.5

A. The modulator power for 100percent modulation is

i. 6 Wj. 12 Wk. 18 Wl. 24 W

9. The circuit that recovers theoriginal modulating informationfrom an AM signal is known as a

i. modulatorj. demodulatork. mixerl. crystal set

10. The most commonly usedamplitude demodulator is the

i. diode mixerj. balanced modulator


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k. envelope detectorl. crystal filter

11. A circuit that generates theupper and lower sidebands but nocarrier is called a(n)

i. amplitude modulator

j. diode detectork. class C amplifierl. balanced modulator

12. The inputs to a balancedmodulator are 1 MHz and a carrierof 1.5 MHz. The outputs are

i. 500 kHzj. 2.5 MHzk. 1.5 MHz

l. all of the abovem. a and b

13. A widely used balancedmodulator is called the

i. diode bridge circuitj. full-wave bridge rectifierk. lattice modulatorl. balanced bridge modulator

14. In a diode ring modulator, thediodes act like

i. variable resistorsj. switchesk. rectifiersl. variable capacitors

15. The output of a balancedmodulator is

i. AM

j. FMk. SSBl. DSB

16. The principal circuit in thepopular 1496/1596 IC balancedmodulator is a

i. differential amplifierj. rectifier

k. bridgel. constant current source

17. The most commonly used filterin SSB generators uses

i. LC networksj. mechanical resonators

k. crystalsl. RC networks and op amps

18. The equivalent circuit of aquartz crystal is a

i. series resonant circuitj. parallel resonant circuitk. neither a nor bl. both a and b

19. A crystal lattice filter hascrystal frequencies of 27.5 and27.502 MHz. The bandwidth isapproximately

i. 2 kHzj. 3 kHzk. 27.501 MHzl. 55.502 MHz

20. An SSB generator has a

sideband filter centered at 3.0MHz. The modulating signal is 3kHz. To produce both upper andlower sidebands, the followingcarrier frequencies must beproduced:

i. 2.7 and 3.3 MHzj. 3.3 and 3.6 MHzk. 2997 and 3003 kHzl. 3000 and 3003 kHz

21. In the phasing method of SSBgeneration, one sideband iscanceled out due to

i. phase shiftj. sharp selectivityk. carrier suppressionl. phase inversion


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22. A balanced modulator used todemodulate a SSB signal is calleda(n)

i. transponderj. product detectork. converter

l. modulator

23. Frequency translation is donewith a circuit called a

i. summerj. multiplierk. filterl. mixer

24. The inputs to a mixer are fo

and fm. In down conversion, whichof the following mixer outputsignals is selected?

i. foj. fmk. fofml. fo+ fm

25. Mixing for frequencyconversion is the same as

i. rectificationj. AMk. linear summingl. filtering

26. Which of the following can beused as a mixer?

i. balanced modulatorj. FETk. diode modulator

l. all of the above

27. The desired output from amixer is usually selected with a

i. phase-shift circuitj. crystal filterk. resonant circuitl. transformer

28. The two inputs to a mixer arethe signal to be translated and asignal from a(n)

i. modulatorj. filterk. antenna

l. LO

29. An NE602 mixer IC has adifference output of 10.7 MHz.The input is 146.8 MHz. The localoscillator frequency is

i. 101.9 MHzj. 125.4 MHzk. 131.6 MHzl. 157.5 MHz

CHAPTER 4FREQUENCY MODULATION

1. The amount of frequencydeviation from the carrier centerfrequency in an FM transmitter isproportional to what characteristicof the modulating signal?

m. Amplituden. Frequency

o. Phasep. Shape

2. Both FM and PM are types ofwhat kind of modulation?

m. Amplituden. Phaseo. Anglep. Duty cycle

3. If the amplitude of themodulating signal decreases, thecarrier deviation

m. increasesn. decreaseso. remains constantp. goes to zero


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4. On an FM signal, maximumdeviation occurs at what point onthe modulating signal?

m. zero-crossing pointsn. peak positive amplitudeo. peak negative amplitude

p. both b and c

5. In PM, a frequency shift occurswhile what characteristic of themodulating signal is changing?

m. shapen. phaseo. frequencyp. amplitude

6. Maximum frequency deviationof a PM signal occurs at

m. zero crossing pointsn. peak positive amplitudeo. peak negative amplitudep. peak positive or negative

amplitudes

7. In PM, carrier frequencydeviation is not proportional to:

m. modulating signalamplitude

n. carrier amplitude andfrequency

o. modulating signalfrequency

p. modulator phase shift

8. To compensate for increasesin carrier frequency deviation with

an increase in modulating signalfrequency, what circuit is usedbetween the modulating signal andthe phase modulator?

m. low-pass filtern. high-pass filtero. phase shifterp. bandpass filter

9. The FM produced by PM iscalled

m. FMn. PMo. Indirect FMp. Indirect PM

10. If the amplitude of themodulating signal applied to aphase modulator is constant, theoutput signal will be

m. zeron. the carrier frequencyo. above the carrier

frequencyp. below the carrier

frequency

11. A 100 MHz carrier is deviated50 kHz by a 4 kHz signal. Themodulation index is

m. 5n. 8o. 12.5p. 20

12. The maximum deviation of anFM carrier is 2 kHz by a maximummodulating signal of 400 Hz. Thedeviation ratio is

n. 0.2o. 5p. 8q. 40

13. A 70 kHz carrier has a

frequency deviation of 4 kHz with a1000 Hz signal. How manysignificant sideband pairs areproduced?

m. 4n. 5o. 6p. 7


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p. push-pull

25. Frequency modulationtransmitters are more efficientbecause their power is increasedby what type of amplifier?

m. Class An. Class Bo. Class Cp. all of the above

26. Noise interferes mainly withmodulating signals that are

m. sinusoidaln. nonsinusoidalo. low frequencies

p. high frequencies

27. Pre-emphasis circuits boostwhat modulating frequenciesbefore modulation?

m. high frequenciesn. mid-range frequencieso. low frequenciesp. all of the above

28. A pre-emphasis circuit is am. low-pass filtern. high-pass filtero. phase shifterp. bandpass filter

29. Pre-emphasis is compensatedfor at the receiver by a

m. Phase invertern. Bandpass filter

o. High-pass filterp. Low-pass filter

30. The cut-off frequency of pre-emphasis and de-emphasis circuitis

a. 1 kHzb. 2.122 kHzc. 5 kHz

d. 75 kHz

CHAPTER 5

FREQUENCY MODULATION

CIRCUITS

1. Another name for a VVC isq. PIN dioder. Varactor diodes. Snap diodet. Hot-carrier diode

2. The depletion region in ajunction diode forms what part of acapacitor?

q. plates

r. leadss. packaget. dielectric

3. Increasing the reverse bias ona varactor diode will cause itscapacitance to

q. decreaser. increases. remain the same

t. drop to zero

4. The capacitance of a varactordiode is in what general range?

q. pFr. nF

s. Ft. F

5. The frequency change of a

crystal oscillator produced by avaractor diode isq. zeror. smalls. mediumt. large

6. A phase modulator varies thephase shift of the


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q. carrierr. modulating signals. both a and bt. neither a or b

7. The widest phase variation is

obtained with a(n)q. RC low-pass filterr. RC high-pass filters. LR low-pass filtert. LC resonant circuit

8. The small frequency changeproduced by a phase modulatorcan be increased by using a(n)

q. amplifier

r. mixers. frequency multipliert. frequency divider

9. A crystal oscillator whosefrequency can be changed by aninput voltage is called a(n)

q. VCOr. VXOs. VFO

t. VHF

10. Which oscillators are preferredfor carrier generators because oftheir good frequency stability?

q. LCr. RCs. LRt. crystal

11. Which of the followingfrequency demodulators requiresan input limiter?

q. Foster-Seeleydiscriminator

r. Pulse-averagingdiscriminator

s. Quadrature detectort. PLL

12. Which discriminator averagespulses in a low-pass filter?

r. Ratio detectors. PLLt. Quadrature detector

u. Foster-Seeleydiscriminator

13. Which frequency demodulatoris considered the best overall?

q. Ratio detectorr. PLLs. Quadraturet. Pulse-averaging

discriminator

14. In a pulse-averagingdiscriminator, the pulses areproduced by a(n)

q. Astable multivibratorr. Zero-crossing detectors. One shott. Low-pass filter

15. A reactance modulator looks

like a capacitance of 35 pF inparallel with the oscillator-tuned

circuit whose inductance is 50 Hand capacitance is 40 pF. What isthe center frequency of theoscillator prior to FM?

q. 1.43 MHzr. 2.6 MHzs. 3.56 MHzt. 3.8 MHz

16. Which of the following is trueabout the NE566 IC?

q. It is a VCO.r. Its output is sinusoidal.s. It is an FM demodulator.t. It uses LC tuned circuits.


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17. An FM demodulator that usesa differential amplifier and tunedcircuits to convert frequencyvariations into voltage variations isthe

q. Quadrature detector

r. Foster-Seeleydiscriminator

s. Differential peak detector

t. Phase-locked loop

18. The output amplitude of thephase detector in a quadraturedetector is proportional to

q. Pulse width

r. Pulse frequencys. Input amplitudet. The phase shift value at

center frequency

19. The input to a PLL is 2 MHz.In order for the PLL to be locked,the VCO output must be

q. 0 MHzr. 1 MHz

s. 2 MHzt. 4 MHz

20. Decreasing the input frequencyto a locked PLL will cause theVCO output to

q. decreaser. increases. remain constantt. jump to the free-running

frequency

21. The range of frequencies overwhich a PLL will track input signalvariations is known as the

q. circuit bandwidthr. capture ranges. band of acceptancet. lock range

22. The band of frequencies overwhich a PLL will acquire orrecognize an input signal is calledthe

q. circuit bandwidthr. capture range

s. band of acceptancet. lock range

23. Over a narrow range offrequencies, the PLL acts like a

q. Low-pass filterr. Bandpass filters. Tunable oscillatort. Frequency modulator

24. The output of a PLL frequencydemodulator is taken from the

q. Low-pass filterr. VCOs. Phase detectort. none of the above

CHAPTER 6

RADIO TRANSMITTERS

1. Which of the following circuitsis not typically part of every radiotransmitter?

u. carrier oscillatorv. driver amplifierw. mixerx. final power amplifier

2. Class C amplifiers are notused in which type of transmitter?

u. AMv. SSBw. CWx. FM

3. A circuit that isolates thecarrier oscillator from load changesis called a

u. final amplifier


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v. driver amplifierw. linear amplifierx. buffer amplifier

4. A class B amplifier conductsfor how many degrees of an input

sine waveu. 90 to 150

v. 180

w. 180 to 360

x. 360

5. Bias for a class C amplifierproduced by an input RC networkis known as

u. signal bias

v. self biasw. fixed external biasx. threshold bias

6. An FM transmitter has a 9 MHzcrystal carrier oscillator andfrequency multipliers of 2, 3, and 4.The output frequency is

u. 54 MHzv. 108 MHzw. 216 MHzx. 288 MHz

7. The most efficient RF poweramplifier is which class amplifier?

u. Av. ABw. B

x. C

8. Collector current in a class Camplifier is a

u. sine wavev. half sine wavew. pulsex. square wave

9. The maximum power of typicaltransistor RF power amplifiers is inwhat range?

u. milliwattsv. wattsw. hundreds of watts

x. kilowatts

10. Self-oscillation in a transistoramplifier is usually caused by

u. excessive gainv. stray inductancew. internal capacitancex. unmatched impedances

11. Neutralization is the process ofu. canceling the effect of

internal devicecapacitance

v. by passing undesiredalternating current

w. reducing gainx. eliminating harmonics

12. Maximum power transferoccurs when what relationshipexists between the generatorimpedance Zi and the load

impedance Zl?v. Zi= Zlw. Zi> Zlx. Zi< Zl

y. Zi= 0

13. Which of the following is not abenefit of a toroid RF inductor?

u. no shielding requiredv. fewer turns of wire

w. higher Qx. self-supporting

14. A toroid is au. type of inductorv. transformerw. magnetic corex. coil holder


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15. Which of the following is notcommonly used for impedancematching in a transmitter?

u. resistive attenuatorv. transformerw. L network

x. T network

16. To match a 6 amplifier

impedance to a 72 antennaload, a transformer must have aturns ratio Np/Nsof

u. 0.083v. 0.289w. 3.46x. 12

17. Impedance matching in abroadband linear RF amplifier ishandled with a(n)

u. L networkv. parallel tuned circuitw. Pi networkx. Balun

18. A class C amplifier has a

supply voltage of 24 V and acollector current of 2.5 A. Itsefficiency is 80 percent. The RFoutput power is

u. 24 Wv. 48 Ww. 60 Wx. 75 W

19. Which of the following is not a

benefit of speech-processingcircuits?

u. improved frequencystability

v. increased average outputpower

w. limited bandwidthx. prevention of

overmodulation

20. In an AM transmitter, a clippercircuit eliminates

u. harmonicsv. splatterw. overdeviation

x. excessive gain

21. In a speech-processing circuit,a low-pass filter prevents

u. overdeviationv. overmodulationw. high gainx. excessive signal

bandwidth

22. The gain of a transistoramplifier is

u. inversely proportional tocollector current

v. directly proportional tofrequency

w. directly proportional tocollector current

x. inversely proportional tofrequency

23. What values of L and C in an Lnetwork are required to match a 10

transistor amplifier impedance to

a 50 load at 27 MHz?u. L = 47 nH, C = 185 pFv. L = 118 nH, C = 236 pF

w. L = 0.13 H, C = 220 pF

x. L = 0.3 H, C = 330 pF

CHAPTER 7COMMUNICATIONS RECEIVERS

1. The simplest receiver is a(n)y. RF amplifierz. demodulatoraa. AF amplifierbb. tuned circuit


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2. The key conceptual circuit in asuperhet receiver is the

y. mixerz. RF amplifieraa. demodulatorbb. AF amplifier

3. Most of the gain and selectivityin a superhet is obtained in the

y. RF amplifierz. mixeraa. IF amplifierbb. AF amplifier

4. The sensitivity of a receiverdepends upon the receivers

overally. bandwidthz. selectivityaa. noise responsebb. gain

5. The ability of a receiver toseparate one signal from others onclosely adjacent frequencies iscalled the

y. sensitivityz. S/N ratioaa. selectivitybb. gain

6. A mixer has a signal input of50 MHz and an LO frequency of 59MHz. The IF is

y. 9 MHzz. 50 MHz

aa. 59 MHzbb. 109 MHz

7. A signal 2 times the IF awayfrom the desired signal that causesinterference is referred to as a(n)

y. ghostz. imageaa. phantom

bb. inverted signal

8. A receiver has a desired inputsignal of 18 MHz and an LOfrequency of 19.6 MHz. Theimage frequency is

y. 1.6 MHzz. 18 MHzaa. 19.6 MHzbb. 21.2 MHz

9. The main cause of imageinterference is

y. poor front-end selectivityz. low gainaa. a high IF

bb. a low S/N ratio

10. For best image rejection, the IFfor a 30 MHz signal would be

y. 455 kHzz. 3.3 MHzaa. 9 MHzbb. 55 MHz

11. A tuned circuit is resonant at 4

MHz. Its Q is 100. The bandwidthis

y. 400 Hzz. 4 kHzaa. 40 kHzbb. 400 kHz

12. A crystal filter has a 6 dB

bandwidth of 2.6 kHz and a 60 dBbandwidth of 14 kHz. The shapefactor is

z. 0.186aa. 5.38bb. 8.3cc. 36.4


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13. Most internal noise comesfrom

y. shot noisez. transit-time noiseaa. thermal agitationbb. skin effect

14. Which of the following is not asource of external noise?

y. thermal agitationz. auto ignitionsaa. the sunbb. fluorescent lights

15. Noise can be reduced byy. widening the bandwidth

z. narrowing the bandwidthaa. increasing temperaturebb. increasing transistor

current levels

16. Noise at the input to a receivercan be as high as several

y. microvoltsz. millivoltsaa. volts

bb. kilovolts

17. Which circuit contributes mostto the noise in a receiver?

y. IF amplifierz. AF amplifieraa. demodulatorbb. mixer

18. Which noise figure represents

the lowest noise?y. 1.6 dBz. 2.1 dBaa. 2.7 dBbb. 3.4 dB

19. Which filter shape factorrepresents the best skirtselectivity?

y. 1.6z. 2.1aa. 5.3bb. 8

20. Which input signal below

represents the best receiversensitivity?

y. 0.5 V

z. 1 V

aa. 1.8 V

bb. 2 V

21. The transistor with the lowestnoise figure in the microwaveregion is a(n)

y. MOSFETz. Dual-gate MOSFETaa. JFETbb. MESFET

22. The AGC circuits usuallycontrol the gain of the

y. mixerz. detectoraa. IF amplifiers

bb. audio amplifiers

23. Selectivity is obtained in mostreceivers from

y. crystal filtersz. mechanical filtersaa. double-tuned circuitsbb. audio filters

24. Widest bandwidth in a double-

tuned circuit is obtained withu. undercouplingv. critical couplingw. optimum couplingx. overcoupling

25. Automatic gain control permitsa wide range of signal amplitudes


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to be accommodated by controllingthe gain of the

q. RF amplifierr. IF amplifiers. mixert. AF amplifier

26. In an IF amplifier with reverseAGC, a strong signal will cause thecollector current to

q. increaser. decreases. remain the samet. drop to zero

27. Usually AGC voltage is derived

by theq. RF amplifierr. IF amplifiers. demodulatort. AF amplifier

28. An AFC circuit is used tocorrect for

q. audio distortionr. strong input signals

s. instability in the IFamplifier

t. frequency drift in the LO

29. A circuit that keeps the audiocut off until a signal is received isknown as

q. a squelchr. AFCs. AGC

t. a noise blanker

30. A BFO is used in thedemodulation of which types ofsignals?

a. AMb. FMc. SSB or CWd. QPSK

31. Which of the following circuitsare not typically shared in an SSBtransceiver?

a. crystal filterb. mixers

c. power supplyd. LO

32. The basic frequencysynthesizer circuit is a(n)

a. mixerb. frequency multiplierc. frequency dividerd. PLL

33. The output frequencyincrement of a frequencysynthesizer is determined by the

a. frequency division ratiob. reference input to the

phase detectorc. percentage of output

frequencyd. frequency multiplication

factor

34. The output frequency of asynthesizer is changed by varyingthe

a. reference input to thephase detector

b. frequency division ratioc. frequency multiplication

factord. mixer LO frequency

35. The bandwidth of a parallel LC

circuit can be increased bya. increasing XCb. decreasing XLc. decreasing coil resistanced. a resistor connected in

parallel

36. The upper and lower cutofffrequencies of a tuned circuit are


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6. The circuit that performsdemultiplexing in an FDM systemis a(n)

cc. op ampdd. bandpass filter

ee. discriminatorff. subcarrier oscillator

7. Most FDM telemetry systemsuse

cc. AMdd. FMee. SSBff. PSK

8. The best frequencydemodulator is the

cc. PLL discriminatordd. pulse-averaging

discriminatoree. Foster-Seeley

discriminatorff. ratio detector

9. The modulation used in FDM

telephone systems iscc. AMdd. FMee. SSBff. PSK

10. The FDM telephone systemsaccommodate many channels by

cc. increasing the multiplexersize

dd. using many final carriersee. narrowing the bandwidth ofeach

ff. using multiple levels ofmultiplexing

11. In FM stereo broadcasting, theL + R signal

cc. double-sidebandmodulates a subcarrier

dd. modulates the FM carrieree. frequency modulates a

subcarrierff. is not transmitted

12. In FM stereo broadcasting, theLR signal

dd. double-sidebandmodulates a subcarrier

ee. modulates the FM carrierff. frequency modulates a

subcarriergg. is not transmitted

13. The SCA signal if used in FMbroadcasting is transmitted via

cc. a 19 kHz subcarrierdd. a 38 kHz subcarrieree. a 67 kHz subcarrierff. the main FM carrier

14. In TDM, multiple signalscc. share a common

bandwidth

dd. modulate subcarriersee. are sampled at high

speedsff. take turns transmitting

15. In TDM, each signal may usethe full bandwidth of the channel

cc. truedd. false

16. Sampling an analog signalproducescc. PAMdd. AMee. FMff. PCM


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17. The maximum bandwidth thatan analog signal can use with asampling frequency of 108 kHz is

cc. 27 kHzdd. 54 kHzee. 108 kHz

ff. 216 kHz

18. Pulse-amplitude modulationsignals are multiplexed by using

cc. subcarriersdd. bandpass filtersee. A/D convertersff. FET switches

19. In PAM demultiplexing, the

receiver clock is derived fromcc. standard radio station

WWVdd. a highly accurate internal

oscillatoree. the PAM signal itselfff. the 60 Hz power line

20. In a PAM/TDM system,keeping the multiplexer and

DEMUX channels step with oneanother is done by a

cc. clock recovery circuitdd. sync pulseee. samplingff. sequencer

21. Transmitting data as serialbinary words is called

cc. digital communications

dd. quantizingee. PAMff. PCM

22. Converting analog signals todigital is done by sampling and

cc. quantizingdd. compandingee. pre-emphasis

ff. mixing

23. A quantizer is a(n)cc. multiplexerdd. demultiplexeree. A/D converter

ff. D/A converter

24. Emphasizing low-level signalsand compressing higher-levelsignals is called

y. quantizingz. compandingaa. pre-emphasisbb. sampling

25. Which of the following is not abenefit of companding?

u. minimizes noisev. minimizes number of bitsw. minimizes quantizing errorx. minimizes signal

bandwidth

26. A telephone system usingTDM and PCM is called

u. PBXv. RS-232w. T-1x. Bell 212

27. An IC that contains A/D andD/A converters, companders, andparallel-to-serial converters iscalled a

u. codec

v. data converterw. multiplexerx. modem

28. Pulse-code modulation ispreferred to PAM because of its

u. resistance to quantizingerror

v. simplicity


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w. lower costx. superior noise immunity

CHAPTER 9

ANTENNAS AND

TRANSMISSION LINES

1. The most commonly usedtransmission line is a

gg. two-wire balance linehh. single wireii. three-wire line

jj. coax

2. The characteristic impedance

of a transmission line does notdepend upon its

gg. lengthhh. conductor diameterii. conductor spacing

jj. none of the above

3. Which of the following is not acommon transmission lineimpedance?

gg. 50hh. 75

ii. 120

jj. 300

4. For maximum absorption ofpower at the antenna, therelationship between thecharacteristic impedance of theline Zoand the load impedance Zl

should begg. Zo= Zlhh. Zo> Zlii. Zo< Zl

jj. Zo= 0

5. The mismatch betweenantenna and transmission line

impedances cannot be correctedfor by

gg. using an LC matchingnetwork

hh. adjusting antenna lengthii. using a balun

jj. adjusting the length oftransmission line

6. A pattern of voltage andcurrent variations along atransmission line not terminated inits characteristic impedance iscalled

gg. an electric fieldhh. radio waves

ii. standing wavesjj. a magnetic field

7. The desirable SWR on atransmission line is

gg. 0hh. 1ii. 2

jj. infinity

8. A 50 coax is connected to a73 antenna. The SWR is

gg. 0.685hh. 1ii. 1.46

jj. 2.92

9. The most desirable reflectioncoefficient is

gg. 0

hh. 0.5ii. 1

jj. infinity

10. A ratio expressing thepercentage of incident voltagereflected on a transmission line isknown as the

gg. velocity factor


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hh. standing wave ratioii. reflection coefficient

jj. line efficiency

11. The minimum voltage along atransmission line is 260 V, while

the maximum is 390 V. The SWRis

gg. 0.67hh. 1.0ii. 1.2

jj. 1.5

12. Three feet is one wavelengthat a frequency of

hh. 100 MHz

ii. 164 MHzjj. 300 MHzkk. 328 MHz

13. At very high frequencies,transmission lines are used as

gg. tuned circuitshh. antennasii. insulators

jj. resistors

14. A shorted quarter-wave line atthe operating frequency acts likea(n)

gg. series resonant circuithh. parallel resonant circuitii. capacitor

jj. inductor

15. A shorted half-wave line at the

operating frequency acts like a(n)ee. capacitorff. inductorgg. series resonant circuithh. parallel resonant circuit

16. A popular half-wavelengthantenna is the

gg. ground plane

hh. end-fireii. collinear

jj. dipole

17. The length of a doublet at 27MHz is

gg. 8.67 ft.hh. 17.3 ft.ii. 18.2 ft.

jj. 34.67 ft.

18. A popular vertical antenna isthe

gg. collinearhh. dipoleii. ground plane

jj. broadside

19. The magnetic field of anantenna is perpendicular to theearth. The antennas polarization

gg. is verticalhh. is horizontalii. is circular

jj. cannot be determined fromthe information given

20. An antenna that transmits orreceives equally well in alldirections is said to be

gg. omnidirectionalhh. bidirectionalii. unidirectional

jj. quasidirectional

21. The horizontal radiation pattern

of a dipole is agg. circlehh. figure eightii. clover leaf

jj. narrow beam

22. The length of a ground planevertical at 146 MHz is

gg. 1.6 ft.


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hh. 1.68 ft.ii. 2.05 ft.

jj. 3.37 ft.

23. The impedance of a dipole isabout

gg. 50hh. 73

ii. 93

jj. 300

24. A directional antenna with twoor more elements is known as a(n)

cc. Folded dipoledd. ground planeee. loop

ff. array

25. The horizontal radiation patternof a vertical dipole is a

y. figure eightz. circleaa. narrow beambb. clover leaf

26. In an Yagi antenna, maximum

direction of radiation is toward they. directorz. driven elementaa. reflectorbb. sky

27. Conductors in mutlielementantennas that do not receiveenergy directly from thetransmission line are known as

y. parasitic elementsz. drives elementsaa. the boombb. receptors

28. A coax has an attenuation of2.4 dB per 100 ft. The attenuationfor 275 ft is

y. 2.4 dB

z. 3.3 dBaa. 4.8 dBbb. 6.6 dB

29. An antenna has a power gainof 15. The power applied to the

antenna is 32 W. The effectiveradiated power is

u. 15 Wv. 32 Ww. 120 Wx. 480 W

30. Which beam width representsthe best antenna directivity?

a. 7

b. 12c. 19

d. 28

31. The radiation pattern ofcollinear and broadside antennasis

a. omnidirectionalb. bidirectionalc. unidirectional

d. clover-leaf shaped

32. Which antenna has aunidirectional radiation pattern andgain?

a. dipoleb. ground planec. Yagid. collinear

33. A wide-bandwidth multielementdriven array is the

a. end-fireb. log-periodicc. Yagid. collinear


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CHAPTER 10

MICROWAVE TECHNIQUES

1. The main benefit of usingmicrowaves is

kk. lower-cost equipment

ll. simpler equipmentmm. greater transmission

distancesnn. more spectrum space for

signals

2. Radio communications areregulated in the United States bythe

kk. Federal Trade

Commissionll. Congressmm. Federal

CommunicationsCommission

nn. Military

3. Which of the following is not adisadvantage of microwaves?

kk. higher-cost equipment

ll. line-of-sight transmissionmm. conventional

components are notusable

nn. circuits are more difficult toanalyze

4. Which of the following is amicrowave frequency?

kk. 1.7 MHz

ll. 750 MHzmm. 0.98 GHznn. 22 GHz

5. Which of the following is not acommon microwave application?

kk. radarll. mobile radiomm. telephone

nn. spacecraftcommunications

6. Coaxial cable is not widelyused for long microwavetransmission lines because of its

kk. high loss

ll. high costmm. large sizenn. excessive radiation

7. Stripline and microstriptransmission lines are usuallymade with

kk. coaxll. parallel wiresmm. twisted pair

nn. PCBs

8. The most common crosssection of a waveguide is a

kk. squarell. circlemm. trianglenn. rectangle

9. A rectangular waveguide has a

width of 1 in. and a height of 0.6 in.Its cutoff frequency is

kk. 2.54 GHzll. 3.0 GHzmm. 5.9 GHznn. 11.8 GHz

10. A waveguide has a cutofffrequency of 17 GHz. Which of thesignals will not be passed by the

waveguide?kk. 15 GHzll. 18 GHzmm. 22 GHznn. 25 GHz

11. Signal propagation in awaveguide is by

kk. electrons


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ll. electric and magneticfields

mm. holesnn. air pressure

12. When the electric field in a

waveguide is perpendicular to thedirection of wave propagation, themode is said to be

ll. vertical polarizationmm. horizontal propagationnn. transverse electricoo. transverse magnetic

13. The dominant mode in mostwaveguide is

kk. TE0,1ll. TE1,2mm. TM0,1nn. TM1,1

14. A magnetic field is introducedinto a waveguide by a

kk. probell. dipolemm. stripline

nn. capacitor

15. A half-wavelength, closedsection of a waveguide that acts asa parallel resonant circuit is knownas a(n)

ii. half-wave sectionjj. cavity resonatorkk. LCR circuitll. directional coupler

16. Decreasing the volume of acavity causes its resonantfrequency to

kk. increasell. decreasemm. remain the samenn. drop to zero

17. A popular microwave mixerdiode is the

kk. Gunnll. Varactormm. Hot carrier

nn. IMPATT

18. Varactor and step-recoverydiodes re widely used in what typeof circuit?

kk. amplifierll. oscillatormm. frequency multipliernn. mixer

19. Which diode is a popularmicrowave oscillator?

kk. IMPATTll. Gunnmm. Varactornn. Schottky

20. Which type of diodes does notordinarily operate with reversebias?

kk. Varactorll. IMPATTmm. Snap-offnn. Tunnel

21. Low-power Gunn diodes arereplacing

kk. Reflex klystronsll. TWTsmm. Magnetronsnn. Varactor diodes

22. Which of the following is not amicrowave tube?

kk. Traveling-wave tubell. Cathode-ray tubemm. Klystronnn. Magnetron


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23. In a klystron amplifier, velocitymodulation of the electron beam isproduced by the

kk. Collectorll. Catcher cavitymm. Cathode

nn. Buncher cavity

24. A reflex klystron is used asa(n)

gg. amplifierhh. oscillatorii. mixer

jj. frequency multiplier

25. For proper operation, a

magnetron must be accompaniedby a

cc. cavity resonatordd. strong electric fieldee. permanent magnetff. high dc voltage

26. The operating frequency ofklystrons and magnetrons is set bythe

cc. cavity resonatorsdd. DC supply voltageee. input signal frequencyff. number of cavities

27. A magnetron is used only asa(n)

cc. amplifierdd. oscillatoree. mixer

ff. frequency multiplier

28. A common application formagnetrons is in

cc. radardd. satellitesee. two-way radioff. TV sets

29. In a TWT, the electron beam isdensity-modulated by a

y. permanent magnetz. modulation transformeraa. Helixbb. cavity resonator

30. The main advantage of a TWTover a klystron for microwaveamplification is

a. lower costb. smaller sizec. higher powerd. wider bandwidth

31. High-power TWTs are

replacing what in microwaveamplifiers?a. MESFETsb. magnetronsc. klystronsd. IMPATT diodes

32. The most widely usedmicrowave antenna is a

a. half-wave dipoleb. quarter-wave probec. single loopd. horn

33. What happens when a hornantenna is made longer?

a. Gain increasesb. beam width decreasesc. both a and bd. neither a nor b

34. A pyramidal horn used at 5GHz has an aperture that is 7 by 9cm. The gain is about

a. 10.5 dBb. 11.1 dBc. 22.6 dBd. 35.8 dB


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35. Given the frequency anddimensions in Question 34 above,the beam width is about

a. 27

b. 53

c. 60

d. 80

36. The diameter of a parabolicreflector should be at least howmany wavelengths at the operatingfrequency?

a. 1b. 2c. 5d. 10

37. The point where the antenna ismounted with respect to theparabolic reflector is called the

a. Focal pointb. centerc. locusd. tangent

38. Using a small reflector to beam

waves to the larger parabolicreflector is known asa. Focal feedb. Horn feedc. Cassegrain feedd. Coax feed

39. Increasing the diameter of aparabolic reflector causes which ofthe following:

a. decreased beam widthb. increased gainc. increased beam widthd. a and be. b and cf. none of the above

40. A helical antenna is made upof a coil and a

a. directorb. reflectorc. dipoled. horn

41. The output of a helical antennais

a. vertically polarizedb. horizontally polarizedc. circularly polarizedd. both a and b

42. A common omnidirectionalmicrowave antenna is the

a. hornb. parabolic reflectorc. helicald. bicone

CHAPTER 11

INTRODUCTION TO SATELLITE

COMMUNICATIONS

1. As the height of a satellite orbitgets lower, the speed of the

satelliteoo. increasepp. decreasesqq. remains the samerr. none of the above

2. The main function of acommunications satellite is as a(n)

oo. Repeaterpp. Reflector

qq. Beaconrr. Observation platform

3. The key electronic componentin a communications satellite is the

oo. Telemetrypp. On-board computerqq. Command and control

system


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rr. Transponder

4. A circular orbit around theequator with a 24-h period is calleda(n)

oo. Elliptical orbit

pp. Geostationary orbitqq. Polar orbitrr. Transfer orbit

5. A satellite stays in orbitbecause the following two factorsare balanced.

oo. satellite weight and speedpp. gravitational pull and

inertia

qq. centripetal force andspeed

rr. satellite weight and the pullof the moon and sun

6. The height of a satellite in asynchronous equatorial orbit is

oo. 100 mi.pp. 6800 mi.qq. 22,300 mi.rr. 35,860 mi.

7. Most satellites operate inwhich frequency band?

oo. 30 to 300 MHzpp. 300 MHz to 3 GHzqq. 3 GHz to 30 GHzrr. above 300 GHz

8. The main power sources for asatellite are

oo. batteriespp. solar cellsqq. fuel cellsrr. thermoelectric generators

9. The maximum height of anelliptical orbit is called the

oo. perigeepp. apex

qq. zenithrr. apogee

10. Batteries are used to power allsatellite subsystems

oo. at all times

pp. only during emergenciesqq. during eclipse periodsrr. to give the solar arrays a

rest

11. The satellite subsystem thatmonitors and controls the satelliteis the

oo. propulsion subsystempp. power subsystem

qq. communicationssubsystem

rr. telemetry, tracking, andcommand subsystem

12. The basic technique used tostabilize a satellite is

pp. gravity-forward motionbalance

qq. spinrr. thruster control

ss. solar panel orientation

13. The jet thrusters are usuallyfired to

oo. maintain altitudepp. put the satellite into the

transfer orbitqq. inject the satellite into the

geosynchronous orbitrr. bring the satellite back to

earth

14. Most commercial satelliteactivity occurs in which band(s)?

oo. Lpp. C and Kuqq. Xrr. S and P


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15. How can multiple earthstations share a satellite on thesame frequencies?

mm. frequency reusenn. multiplexingoo. mixing

pp. they cant

16. The typical bandwidth of asatellite band is

oo. 36 MHzpp. 40 MHzqq. 70 MHzrr. 500 MHz


usually a part of a transponder?oo. LNApp. mixerqq. modulatorrr. HPA

18. The satellite communicationschannels in a transponder aredefined by the

oo. LNA

pp. bandpass filterqq. mixerrr. input signals

19. The HPAs in most satellitesare

oo. TSTspp. klystronsqq. vacuum tubesrr. magnetrons

20. The physical location of asatellite is determined by its

oo. distance from the earthpp. latitude and longitudeqq. reference to the starsrr. position relative to the sun

21. The receive GCE system in anearth stations performs whatfunction(s)?

oo. modulation andmultiplexing

pp. up conversion

qq. demodulation anddemultiplexing

rr. down conversion

22. Which of the following types ofHPA is not used in earth stations?

oo. TWTpp. transistorqq. klystronrr. Magnetron

23. A common up-converter anddown-converter IF is

oo. 36 MHzpp. 40 MHzqq. 70 MHzrr. 500 MHz

24. The type of modulation usedon voice and video signals is

kk. AMll. FMmm. SSBnn. QPSK

25. The modulation normally usedwith digital data is

gg. AMhh. FMii. SSB

jj. QPSK

26. Which of the following is not atypical output from a GPSreceiver?

gg. latitudehh. speedii. altitude

jj. longitude


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CHAPTER 12

DATA COMMUNICATIONS

1. Data communications refers tothe transmission of

ss. voicett. videouu. computer datavv. all of the above

2. Data communications usesss. analog methodstt. digital methodsuu. either of the abovevv. neither of the above

3. Which of the following is notprimarily a type of datacommunications?

ss. telephonett. teletypeuu. telegraphvv. CW

4. The main reason that serial

transmission is preferred to paralleltransmission is that

ss. Serial is faster.tt. Serial requires only a

single channel.uu. Serial requires multiple

channels.vv. Parallel is too expensive.

5. Mark and space refer

respectively toss. dot and dashtt. message and intervaluu. binary 1 and binary 0vv. on and off

6. The number of amplitude,frequency, or phase changes that

take place per second is known asthe

ss. data rate in bits persecond

tt. frequency of operationuu. speed limit

vv. baud rate

7. Data transmission of onecharacter at a time with start andstop bits is known as what type oftransmission?

ss. asynchronoustt. serialuu. synchronousvv. parallel

8. The most widely used datacommunications code is

ss. Morsett. ASCIIuu. Baudotvv. EBCDIC

9. The ASCII code hasss. 4 bits

tt. 5 bitsuu. 7 bitsvv. 8 bits

10. Digital signals may betransmitted over the telephonenetwork if

ss. their speed is low enoughtt. they are converted to

analog first

uu. they are ac instead of dcvv. they are digital only11. Start and stop bits,respectively, are

ss. mark, spacett. space, markuu. space, spacevv. mark, mark


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12. Which of the following iscorrect?

tt. The bit rate may begreater than the baudrate.

uu. The baud rate may be

greater than the bit rate.vv. The bit and baud rates are

always the same.ww. The bit and baud rates re

not related.

13. A modem convertsss. analog signals to digitaltt. digital signals to analoguu. both a and b

vv. none of the above

14. Slow-speed modems usess. FSKtt. BPSKuu. QPSKvv. QAM

15. A carrier recovery circuit is notneeded with

qq. BPSKrr. QPSKss. DPSKtt. QAM

16. The basic modulator anddemodulator circuits in PSK are

ss. PLLstt. balanced modulatoruu. shift registers

vv. linear summers

17. The carrier used with a BPSKdemodulator is

ss. generated by an oscillatortt. the BPSK signal itselfuu. twice the frequency of the

transmitted carrier

vv. recovered from the BPSKsignal

18. A 9600-baud-rate signal canpass over the voice-gradetelephone line if which kind of

modulation is used?ss. BPSKtt. QPSKuu. DPSKvv. QAM

19. Quadrature amplitudemodulation is

ss. amplitude modulation onlytt. QPSK only

uu. AM plus QPSKvv. AM plus FSK

20. A QAM modulator does notuse a(n)

ss. XNORtt. bit splitteruu. balanced modulatorvv. 2-to-4 level converter

21. A rule or procedure thatdefines how data is to betransmitted is called a(n)

ss. handshakett. error-detection schemeuu. data specificationvv. protocol

22. A popular PC protocol isss. parity

tt. Xmodemuu. CRCvv. LRC

23. A synchronous transmissionusually begins with whichcharacter?

ss. SYNtt. STX


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uu. SOHvv. ETB

24. The characters making up themessage in a synchronoustransmission are collectively

referred to as a dataoo. setpp. sequenceqq. blockrr. collection

25. Bit errors in data transmissionare usually caused by

kk. equipment failuresll. typing mistakes

mm. noisenn. poor S/N ratio at the

receiver

26. Which of the following is not acommonly used method of errordetection?

kk. parityll. BCCmm. CRC

nn. redundancy

27. Which of the following wordshas the correct parity bit? Assumeodd parity. The last bit is the paritybit.

gg. 1111111 1hh. 1100110 1ii. 0011010 1

jj. 0000001 0

28. Another name for parity isgg. vertical redundancy

checkhh. block check characterii. longitudinal redundancy

checkjj. cyclical redundancy check

29. Ten bit errors occur in twomillion transmitted. The bit errorrate is

cc. 2 x 10-5

dd. 5 x 10

-5

ee. 5 x 10-6

ff. 2 x 10-6

30. The building block of a parityor BCC generator is a(n)

e. shift registerf. XORg. 2-to-4 level converterh. UART

31. A longitudinal redundancy

check produces a(n)e. block check characterf. parity bitg. CRCh. error correction

32. Dividing the data block by aconstant produces a remainderthat is used for error detection. Itis called the

e. vertical redundancy check

f. horizontal redundancycheckg. block check characterh. cyclical redundancy check

33. A CRC generator uses whichcomponents?

e. balanced modulatorf. shift registerg. binary adderh. multiplexer

34. Which of the following is not aLAN?

e. PBX systemf. hospital systemg. office building systemh. cable TV system


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35. The fastest LAN topology isthe

e. ringf. busg. star

h. square

36. Which is not a common LANmedium?

e. twin leadf. twisted pairg. fiber-optic cableh. coax

37. A mainframe computer

connected to multiple terminalsand PCs usually uses whichconfiguration?

e. busf. ringg. starh. tree

38. A small telephone switchingsystem that can be used as a LANis called a

e. ringf. WANg. UARTh. PBX

39. Which medium is the leastsusceptible to noise?

g. twin leadh. twisted pairi. fiber-optic cable

j. coax

40. Which medium is the mostwidely used in LANs?

e. twin leadf. twisted pairg. fiber-optic cableh. coax

41. Transmitting the data signaldirectly over the medium isreferred to as

e. basebandf. broadbandg. ring

h. bus

42. The technique of usingmodulation and FDM to transmitmultiple data channels of acommon medium is known as

e. basebandf. broadbandg. ringh. bus

43. What is the minimumbandwidth required to transmit a56 kbits/s binary signal with nonoise?

a. 14 kHzb. 28 kHzc. 56 kHzd. 112 kHz

44. Sixteen different levels(symbols) are used to encodebinary data. The channelbandwidth is 36 MHz. Themaximum channel capacity is

a. 18 Mbits/sb. 72 Mbits/s

c. 288 Mbits/sd. 2.176 Gbits/s

45. What is the bandwidth requiredto transmit at a rate of 10 Mbits/sin the presence of a 28-dB S/Nradio?

a. 1.075 MHzb. 5 MHzc. 10 MHzd. 10.75 MHz


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46. Which circuit is common toboth frequency-hopping and direct-sequence SS transmitters?

a. correlatorb. PSN code generatorc. frequency synthesizer

d. sweep generator

47. Spread spectrum stationssharing a band are identified byand distinguished from oneanother by

a. PSN codeb. frequency of operationc. clock rated. modulation type

48. The type of modulation mostoften used with direct-sequenceSS is

a. QAMb. SSBc. FSKd. PSK

49. The main circuit in a PSN

generator is a(n)a. X-ORb. multiplexerc. shift registerd. mixer

50. To a conventional narrowbandreceiver, an SS signal appears tobe like

a. noise

b. fadingc. a jamming signald. an intermittent connection

51. Which of the following is not abenefit of SS?

a. jam-proofb. securityc. immunity to fading

d. noise proof

52. Spread spectrum is a form ofmultiplexing.

a. trueb. false

53. The most critical and difficultpart of receiving a direct-sequenceSS signal is

a. frequency synthesisb. synchronismc. PSN code generationd. carrier recovery

CHAPTER 13

FIBER-OPTIC

COMMUNICATIONS

1. Which of the following is not acommon application of fiber-opticcable?

ww. computer networksxx. long-distance telephone

systemsyy. closed circuit TVzz. consumer TV

2. Total internal reflection takesplace if the light ray strikes theinterface at an angle with whatrelationship to the critical angle?

ww. less thanxx. greater than

yy. equal tozz. zero

3. The operation of a fiber-opticcable is based on the principle of

ww. refractionxx. reflectionyy. dispersionzz. absorption


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4. Which of the following is not acommon type of fiber-optic cable?

ww. single-mode step-indexxx. multimode graded-indexyy. single-mode graded-index

zz. multimode step-index

5. Cable attenuation s usuallyexpressed in terms of

ww. loss per footxx. dB/km.yy. intensity per milezz. voltage drop per inch

6. Which cable length has thehighest attenuation?

ww. 1 kmxx. 2 kmyy. 95 ft.zz. 500 ft.

7. The upper pulse rate andinformation-carrying capacity of acable is limited by

ww. pulse shorteningxx. attenuationyy. light leakagezz. modal dispersion

8. The core of a fiber-optic cableis made of

ww. airxx. glassyy. diamond

zz. quartz

9. The core of a fiber-optic cableis surrounded by

ww. wire braid shieldxx. Kevlaryy. claddingzz. plastic insulation

10. The speed of light in plasticcompared to the speed of light inair is

ww. lessxx. moreyy. the same

zz. zero11. Which of the following is not amajor benefit of fiber-optic cable?

ww. immunity from interferencexx. no electrical safety

problemsyy. excellent data securityzz. lower cost

12. The main benefit of light-wave

communications over microwavesor any other communicationsmedia are

xx. lower costyy. better securityzz. wider bandwidthaaa. freedom from

interference


part of the optical spectrum?ww. infraredxx. ultravioletyy. visible colorzz. x-rays

14. The wavelength of visible lightextends from

ww. 0.8 to 1.6 m.xx. 400 to 750 nm.

yy. 200 to 600 nm.zz. 700 to 1200 nm.

15. The speed of light isuu. 186,000 mi/h.vv. 300,000 mi/h.ww. 300,000 m/sxx. 300,000,000 m/s


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16. Refraction is theww. bending of light wavesxx. reflection of light wavesyy. distortion of light waveszz. diffusion of light waves

17. The ratio of the speed of lightin air to the speed of light inanother substance is called the

ww. speed factorxx. index of reflectionyy. index of refractionzz. speed gain

18. A popular light wavelength in

fiber-optic cable isww. 0.7 m.

xx. 1.3 m.

yy. 1.5 m.

zz. 1.8 m.

19. Which type of fiber-optic cableis the most widely used?

ww. single-mode step-indexxx. multimode step-index

yy. single-mode graded-indexzz. multimode graded-index

20. Which type of fiber-optic cableis best for very high speed data?

ww. single-mode step-indexxx. multimode step-indexyy. single-mode graded-indexzz. multimode graded-index

21. Which type of fiber-optic cablehas the least modal dispersion?

ww. single-mode step-indexxx. multimode step-indexyy. single-mode graded-indexzz. multimode graded-index

22. Which of the following is not afactor in cable light loss?

ww. reflectionxx. absorptionyy. scatteringzz. dispersion

23. A distance of 8 km is the same

asww. 2.5 mi.xx. 5 mi.yy. 8 mi.zz. 12.9 mi.

24. A fiber-optic cable has a lossof 15 dB/km. The attenuation in acable 1000 ft long is

ss. 4.57 dB

tt. 9.3 dBuu. 24 dBvv. 49.2 dB

25. Fiber-optic cables withattenuations of 1.8, 3.4, 5.9, and18 dB are linked together. Thetotal loss is

oo. 7.5 dBpp. 19.8 dB

qq. 29.1 dBrr. 650 dB

26. Which light emitter is preferredfor high-speed data in a fiber-opticsystem?

oo. incandescentpp. LEDqq. neonrr. laser

27. Most fiber-optic light sourcesemit light in which spectrum?

kk. visiblell. infraredmm. ultravioletnn. x-ray


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ccc. 200 lines per inchddd. 400 lines per inch

5. Group 2 fax uses whichmodulation?

aaa. SSB

bbb. FSKccc. Vestigial sideband AMddd. PSK

6. The most widely used faxstandard is

aaa. Group 1bbb. Group 2ccc. Group 3

ddd. Group 4

7. Group 3 fax uses whichmodulation?

aaa. QAMbbb. FSKccc. Vestigial sideband AMddd. FM

8. Most fax printers are of which

type?aaa. impactbbb. thermalccc. electrosensitiveddd. laser xerographic

9. Facsimile standards are set bythe

aaa. FCCbbb. DOD

ccc. CCITTddd. IEEE

10. What type of graphics arecommonly transmitted by radiofax?

aaa. newspaper textbbb. architectural drawingsccc. cable movies

ddd. satellite weatherphotos

11. The transmission speed ofgroup 4 fax is

aaa. 4800 baud

bbb. 9600 baudccc. 56 kbits/sddd. 192 kbits/s

12. The master control center for acellular telephone system is the

bbb. cell siteccc. mobile telephone switching

officeddd. central officeeee. branch office

13. Each cell site contains aaaa. repeaterbbb. control computerccc. direct link to a branch

exchangeddd. touch-tone processor

14. Multiple cells within an areamay use the same channelfrequencies.

aaa. truebbb. false

15. Cellular telephones use whichtype of operation?

yy. simplex

zz. half-duplexaaa. full-duplexbbb. triplex

16. The maximum frequencydeviation of an FM cellulartransmitter is

aaa. 6 kHzbbb. 12 kHz


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ccc. 30 kHzddd. 45 kHz

17. The maximum output power ofa cellular transmitter is

aaa. 4.75 mW

bbb. 1.5 Wccc. 3 Wddd. 5 W

18. Receive channel 22 is 870.66MHz. Receive channel 23 is

aaa. 870.36 MHzbbb. 870.63 MHzccc. 870.96 MHzddd. 870.69 MHz

19. A transmit channel has afrequency of 837.6 MHz. Thereceive channel frequency is


20. A receive channel frequency is

872.4 MHz. To develop an 82.2MHz IF, the frequency synthesizermust supply an LO signal of


Note: The LO frequency is usually

higher than the receive frequency.

21. The output power of a cellularradio is controlled by theaaa. user or callerbbb. cell siteccc. called partyddd. MTSO

22. When the signal from a mobilecellular unit drops below a certainlevel, what action occurs?

aaa. The unit is handed offto a closer cell.

bbb. The call is terminated.ccc. The MTSO increases

power level.ddd. The cell site switches

antennas.

23. In a cellular radio, the duplexeris a

aaa. ferrite isolatorbbb. waveguide assemblyccc. pair of TR/ATR tubesddd. pair of sharp bandpass

filters

24. The time from the transmissionof a radar pulse to its reception is0.12 ms. The distance to thetarget is how many nautical miles?

ww. 4.85 nmixx. 9.7 nmiyy. 11.2 nmizz. 18.4 nmi

25. The ability of a radar to

determine the bearing to a targetdepends upon the

ss. antenna directivitytt. speed of lightuu. speed of the targetvv. frequency of the signal

26. The pulse duration of a radarsignal is 600 ns. The PRF is 185pulses per second. The duty cycle

is ss. 1.1 percenttt. 5.5 percentuu. 31 percentvv. 47 percent

27. The Doppler effect is used toproduce modulation of which typeof radar signal?


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oo. pulsepp. CW

28. The Doppler effect allowswhich characteristic of a target tobe measured?

oo. distancepp. azimuthqq. altituderr. speed

29. The Doppler effect is a changein what signal characteristicproduced by relative motionbetween the radar set and a

target?kk. amplitudell. phasemm. frequencynn. duty cycle

30. The most widely used radartransmitter component is a

m. klystronn. magnetron

o. TWTp. power transistor

31. Low-power radar transmittersand receiver Los use whichcomponent?

m. GaAs FETn. magnetrono. Gunn diodep. klystron

32. What component in a duplexerprotects the receiver from the high-power transmitter output?

m. waveguiden. bandpass filtero. notch filterp. spark gap

33. Most radar antennas use a

m. dipolen. broadside arrayo. horn and parabolic

reflectorp. collinear array

34. The most common radardisplay is the

m. A scann. color CRTo. liquid-crystal displayp. plan position indicator

35. A radar antenna using multipledipoles or slot antennas in a matrixwith variable phase shifters iscalled a(n)

m. A scann. phased arrayo. broadsidep. circular polarized array

36. Police radars use whichtechnique?

i. pulsej. CW

37. Which of the following is atypical radar operating frequency?

i. 60 MHzj. 450 MHzk. 900 MHzl. 10 GHz

38. The TV signal uses whichtypes of modulation for picture andsound respectively?

i. AM, FM

j. DSB, FMk. FM, AMl. AM, DSB

39. If a TV sound transmitter has acarrier frequency of 197.75 MHz,the picture carrier is

k. 191.75 MHzl. 193.25 MHz


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m. 202.25 MHzn. 203.75 MHz

40. The total bandwidth of anNTSC TV signal is

i. 3.58 MHz

j. 4.5 MHzk. 6 MHzl. 10.7 MHz

41. What is the total number ofinterlaced scan lines in onecomplete frame of a NTSC U.S.TV signal?

i. 262

j. 525k. 480l. 625

42. What keeps the scanningprocess at the receiver in step withthe scanning in the picture tube atthe receiver?

i. nothingj. color burstk. sync pulsesl. deflection oscillators

43. What is the black-and-white ormonochrome brightness signal inTV called?

e. RGBf. color subcarrierg. Q and Ih. luminance Y

44. What is the name of the solid-state imaging device used in TVcameras that converts the light in ascene into an electrical signal?

e. CCDf. photodiode matrixg. vidiconh. MOSFET array

45. The I and Q composite colorsignals are multiplexed onto thepicture carrier by modulating a3.58 MHz subcarrier using

e. FMf. PM

g. DSB AMh. Vestigial sideband AM

46. The assembly around the neckof a picture tube that produces themagnetic fields that deflect andscan the electron beams is calledthe

e. shadow maskf. phosphor

g. electron gunh. yoke

47. The picture and sound carrierfrequencies in a TV receiver IF arerespectively

e. 41.25 and 45.75 MHzf. 45.75 and 41.25 MHzg. 41.75 and 45.25 MHzh. 45.25 and 41.75 MHz

48. The sound IF in a TV receiveris

e. 4.5 MHzf. 10.7 MHzg. 41.25 MHzh. 45.75 MHz

49. What type of circuit is used tomodulate and demodulate the

color signals?e. phase-locked loopf. differential peak detectorg. Quadrature detectorh. balanced demodulator

50. What circuit in the TV receiveris used to develop high voltage


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needed to operate the picturetube?

e. low-voltage power supplyf. horizontal outputg. vertical sweeph. sync separator

51. What ensures proper colorsynchronization at the receiver?

e. sync pulsesf. Quadrature modulationg. 4.5 MHz carrier spacingh. 3.58 MHz color burst

52. Which of the following is not a

benefit of cable TV?c. lower-cost receptiond. greater reliabilitye. less noise, stronger

signalsf. premium cable channels

53. What technique is used topermit hundreds of TV signals toshare a common cable?

e. frequency modulationf. mixingg. frequency division

multiplexingh. time division multiplexing

Data communications refers to thetransmission of

A. voice

B. videoC. computer dataD. all of the above

ANSWER: C

Data communications usesA. analog methodsB. digital methodsC. either of the above

D. neither of the aboveANSWER: C

Which of the following is notprimarily a type of datacommunications?

A. telephoneB. teletypeC. telegraphD. CW

ANSWER: A

The main reason that serialtransmission is preferred to paralleltransmission is that

A. Serial is faster.

B. Serial requires only a singlechannel.C. Serial requires multiplechannels.D. Parallel is too expensive.

ANSWER: B

Mark and space refer respectivelyto

A. dot and dash

B. message and intervalC. binary 1 and binary 0D. on and off

ANSWER: C

The number of amplitude,frequency, or phase changes thattake place per second is known asthe

A. data rate in bits per second

B. frequency of operationC. speed limitD. baud rate

ANSWER: D

Data transmission of one characterat a time with start and stop bits isknown as what type oftransmission?


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A. asynchronousB. serialC. synchronousD. parallel

ANSWER: A

The most widely used datacommunications code is

A. MorseB. ASCIIC. BaudotD. EBCDIC

ANSWER: B

The ASCII code hasA. 4 bits

B. 5 bitsC. 7 bitsD. 8 bits

ANSWER: C

Digital signals may be transmittedover the telephone network if

A. their speed is low enoughB. they are converted to analogfirst

C. they are ac instead of dcD. they are digital onlyANSWER: B

Start and stop bits, respectively,are

A. mark, spaceB. space, markC. space, spaceD. mark, mark

ANSWER: B

Which of the following is correct?A. The bit rate may be greater thanthe baud rate.B. The baud rate may be greaterthan the bit rate.C. The bit and baud rates arealways the same.

D. The bit and baud rates re notrelated.

ANSWER: A

A modem convertsA. analog signals to digital

B. digital signals to analogC. both a and bD. none of the above

ANSWER: C

Slow-speed modems useA. FSKB. BPSKC. QPSKD. QAM

ANSWER: A

A carrier recovery circuit is notneeded with

A. BPSKB. QPSKC. DPSKD. QAM

ANSWER: C

The basic modulator anddemodulator circuits in PSK areA. PLLsB. balanced modulatorC. shift registersD. linears summers

ANSWER: B

The carrier used with a BPSKdemodulator is

A. generated by an oscillatorB. the BPSK signal itselfC. twice the frequency of thetransmitted carrierD. recovered from the BPSK signal

ANSWER: B

A 9600-baud-rate signal can passover the voice-grade telephone


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line if which kind of modulation isused?

A. BPSKB. QPSKC. DPSKD. QAM

ANSWER: D

Quadrature amplitude modulationis

A. amplitude modulation onlyB. QPSK onlyC. AM plus QPSKD. AM plus FSK

ANSWER: C

A QAM modulator does not usea(n)

A. XNORB. bit splitterC. balanced modulatorD. 2-to-4 level converter

ANSWER: A

A rule or procedure that defineshow data is to be transmitted is

called a(n)A. handshakeB. error-detection schemeC. data specificationD. protocol

ANSWER: D

A popular PC protocol isA. parityB. Xmodem

C. CRCD. LRCANSWER: B

A synchronous transmissionusually begins with whichcharacter?

A. SYNB. STX

C. SOHD. ETB

ANSWER: A

The characters making up themessage in a synchronous

transmission are collectivelyreferred to as a data

A. setB. sequenceC. blockD. collection

ANSWER: C

Bit errors in data transmission areusually caused by

A. equipment failuresB. typing mistakesC. noiseD. poor S/N ratio at the receiver

ANSWER: C

Which of the following is not acommonly used method of errordetection?

A. parity

B. BCCC. CRCD. redundancy

ANSWER: D

Which of the following words hasthe correct parity bit? Assume oddparity. The last bit is the parity bit.

A. 1111111 1B. 1100110 1

C. 0011010 1D. 0000001 0ANSWER: B

Another name for parity isA. vertical redundancy checkB. block check characterC. longitudinal redundancy checkD. cyclical redundancy check


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ANSWER: A

Ten bit errors occur in two milliontransmitted. The bit error rate is

A. 2 x 10-5B. 5 x 10-5

C. 5 x 10-6D. 2 x 10-6

ANSWER: C

The building block of a parity orBCC generator is a(n)

A. shift registerB. XORC. 2-to-4 level converterD. UART

ANSWER: B

A longitudinal redundancy checkproduces a(n)

A. block check characterB. parity bitC. CRCD. error correction

ANSWER: A

Dividing the data block by aconstant produces a remainderthat is used for error detection. Itis called the

A. vertical redundancy checkB. horizontal redundancy checkC. block check characterD. cyclical redundancy check

ANSWER: D

A CRC generator uses whichcomponents?A. balanced modulatorB. shift registerC. binary adderD. multiplexer

ANSWER: B

Which of the following is not aLAN?

A. PBX systemB. hospital systemC. office building systemD. cable TV system

ANSWER: D

The fastest LAN topology is theA. ringB. busC. starD. square

ANSWER: B

Which is not a common LAN

medium?A. twin leadB. twisted pairC. fiber-optic cableD. coax

ANSWER: A

A mainframe computer connectedto multiple terminals and PCsusually uses which configuration?

A. busB. ringC. starD. tree

ANSWER: C

A small telephone switchingsystem that can be used as a LANis called a

A. ring

B. WANC. UARTD. PBX

ANSWER: D

Which medium is the leastsusceptible to noise?

A. twin leadB. twisted pair


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C. fiber-optic cableD. coax

ANSWER: C

Which medium is the most widelyused in LANs?

A. twin leadB. twisted pairC. fiber-optic cableD. coax

ANSWER: B

Transmitting the data signaldirectly over the medium isreferred to as

A. baseband

B. broadbandC. ringD. bus

ANSWER: A

The technique of using modulationand FDM to transmit multiple datachannels of a common medium isknown as

A. baseband

B. broadbandC. ringD. bus

ANSWER: B

What is the minimum bandwidthrequired to transmit a 56 kbits/sbinary signal with no noise?

A. 14 kHzB. 28 kHz

C. 56 kHzD. 112 kHzANSWER: B

Sixteen different levels (symbols)are used to encode binary data.The channel bandwidth is 36 MHz.The maximum channel capacity is

A. 18 Mbits/s

B. 72 Mbits/sC. 288 Mbits/sD. 2.176 Gbits/s

ANSWER: C

What is the bandwidth required to

transmit at a rate of 10 Mbits/s inthe presence of a 28-dB S/Nradio?

A. 1.075 MHzB. 5 MHzC. 10 MHzD. 10.75 MHz

ANSWER: A

Which circuit is common to both

frequency-hopping and direct-sequence SS transmitters?

A. correlatorB. PSN code generatorC. frequency synthesizerD. sweep generator

ANSWER: B

Spread spectrum stations sharinga band are identified by and

distinguished from one another byA. PSN codeB. frequency of operationC. clock rateD. modulation type

ANSWER: A

The type of modulation most oftenused with direct-sequence SS is

A. QAM

B. SSBC. FSKD. PSK

ANSWER: D

The main circuit in a PSNgenerator is a(n)

A. X-ORB. multiplexer


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The upper pulse rate andinformation-carrying capacity of acable is limited by

A. pulse shorteningB. attenuationC. light leakage

D. modal dispersionANSWER: B

The core of a fiber-optic cable ismade of

A. airB. glassC. diamondD. quartz

ANSWER: B

The core of a fiber-optic cable issurrounded by

A. wire braid shieldB. KevlarC. claddingD. plastic insulation

ANSWER: C

The speed of light in plastic

compared to the speed of light inair isA. lessB. moreC. the sameD. zero

ANSWER: A

Which of the following is not amajor benefit of fiber-optic cable?

A. immunity from interferenceB. no electrical safety problemsC. excellent data securityD. lower cost

ANSWER: D

The main benefit of light-wavecommunications over microwaves

or any other communicationsmedia are

A. lower costB. better securityC. wider bandwidthD. freedom from interference

ANSWER: C

Which of the following is not part ofthe optical spectrum?

A. infraredB. ultravioletC. visible colorD. x-rays

ANSWER: D

The wavelength of visible lightextends from

A. 0.8 to 1.6 um.B. 400 to 750 nm.C. 200 to 600 nm.D. 700 to 1200 nm.

ANSWER: B

The speed of light isA. 186,000 mi/h.

B. 300,000 mi/h.C. 300,000 m/sD. 300,000,000 m/s

ANSWER: D

Refraction is theA. bending of light wavesB. reflection of light wavesC. distortion of light wavesD. diffusion of light waves

ANSWER: A

The ratio of the speed of light in airto the speed of light in anothersubstance is called the

A. speed factorB. index of reflectionC. index of refractionD. speed gain


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ANSWER: C

A popular light wavelength in fiber-optic cable is

A. 0.7 um.B. 1.3 um.

C. 1.5 um.D. 1.8 um.

ANSWER: B

Which type of fiber-optic cable isthe most widely used?

A. single-mode step-indexB. multimode step-indexC. single-mode graded-indexD. multimode graded-index

ANSWER: B

Which type of fiber-optic cable isbest for very high speed data?

A. single-mode step-indexB. multimode step-indexC. single-mode graded-indexD. multimode graded-index

ANSWER: A

Which type of fiber-optic cable hasthe least modal dispersion?A. single-mode step-indexB. multimode step-indexC. single-mode graded-indexD. multimode graded-index

ANSWER: A

Which of the following is not afactor in cable light loss?

A. reflectionB. absorptionC. scatteringD. dispersion

ANSWER: A

A distance of 8 km is the same asA. 2.5 mi.B. 5 mi.

C. 8 mi.D. 12.9 mi.

ANSWER: B

A fiber-optic cable has a loss of 15dB/km. The attenuation in a cable

1000 ft long isA. 4.57 dBB. 9.3 dBC. 24 dBD. 49.2 dB

ANSWER: A

Fiber-optic cables withattenuations of 1.8, 3.4, 5.9, and18 dB are linked together. The

total loss isA. 7.5 dBB. 19.8 dBC. 29.1 dBD. 650 dB

ANSWER: C

Which light emitter is preferred forhigh-speed data in a fiber-opticsystem?

A. incandescentB. LEDC. neonD. laser

ANSWER: D

Most fiber-optic light sources emitlight in which spectrum?

A. visibleB. infrared

C. ultravioletD. x-rayANSWER: A

Both LEDs and ILDs operatecorrectly with

A. forward biasB. reverse biasC. neither a or b


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D. either a or bANSWER: A

Single-frequency light is calledA. pureB. intense

C. coherentD. monochromatic

ANSWER: D

Laser light is very bright because itis

A. pureB. whiteC. coherentD. monochromatic

ANSWER: C

Which of the following is not acommon light detector?

A. PIN photodiodeB. photovoltaic diodeC. photodiodeD. avalanche photodiode

ANSWER: B

Which of the following is thefastest light sensor?A. PIN photodiodeB. photovoltaic diodeC. phototransistorD. avalanche photodiode

ANSWER: D

Photodiodes operate properly withA. forward bias

B. reverse biasC. neither a or bD. either a or b

ANSWER: B

The product of the bit rate anddistance of a fiber-optic system is2 Gbits-km/s. What is themaximum rate at 5 km?

A. 100 Mbits/sB. 200 Mbits/sC. 400 Mbits/sD. 1000 Gbits/s

ANSWER: C

Which fiber-optic system is better?A. 3 repeatersB. 8 repeatersC. 11 repeatersD. 20 repeaters

ANSWER: A

Printed documents to betransmitted by fax are convertedinto a baseband electrical signal by

the process ofA. reflectionB. scanningC. modulationD. light variation

ANSWER: B

The most commonly used lightsensor in a modern fax machine isa

A. phototubeB. phototransistorC. liquid-crystal displayD. charge coupled device

ANSWER: D

In FM fax, the frequencies forblack and white are

A. 1500 and 2300 HzB. 2300 and 1500 Hz

C. 1300 and 2400 HzD. 1070 and 1270 HzANSWER: A

Which resolution produces thebest quality fax?

A. 96 lines per inchB. 150 lines per inchC. 200 lines per inch


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D. 400 lines per inchANSWER: D

Group 2 fax uses whichmodulation?

A. SSB

B. FSKC. Vestigial sideband AMD. PSK

ANSWER: C

The most widely used fax standardis

A. Group 1B. Group 2C. Group 3

D. Group 4ANSWER: C

Group 3 fax uses whichmodulation?

A. QAMB. FSKC. Vestigial sideband AMD. FM

ANSWER: A

Most fax printers are of whichtype?

A. impactB. thermalC. electrosensitiveD. laser xerographic

ANSWER: B

Facsimile standards are set by the

A. FCCB. DODC. CCITTD. IEEE

ANSWER: C

What type of graphics arecommonly transmitted by radiofax?

A. newspaper textB. architectural drawingsC. cable moviesD. satellite weather photos

ANSWER: D

The transmission speed of group 4fax is

A. 4800 baudB. 9600 baudC. 56 kbits/sD. 192 kbits/s

ANSWER: C

The master control center for acellular telephone system is the

A. cell siteB. mobile telephone switchingofficeC. central officeD. branch office

ANSWER: B

Each cell site contains aA. repeaterB. control computer

C. direct link to a branch exchangeD. touch-tone processorANSWER: A

Multiple cells within an area mayuse the same channel frequencies.

A. trueB. false

ANSWER: A

Cellular telephones use which typeof operation?A. simplexB. half-duplexC. full-duplexD. triplex

ANSWER: C


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The maximum frequency deviationof an FM cellular transmitter is

A. 6 kHzB. 12 kHzC. 30 kHzD. 45 kHz

ANSWER: B

The maximum output power of acellular transmitter is

A. 4.75 mWB. 1.5 WC. 3 WD. 5 W

ANSWER: D

Receive channel 22 is 870.66MHz. Receive channel 23 is

A. 870.36 MHzB. 870.63 MHzC. 870.96 MHzD. 870.69 MHz

ANSWER: D

A transmit channel has afrequency of 837.6 MHz. The

receive channel frequency isA. 729.6 MHzB. 837.6 MHzC. 867.6 MHzD. 882.6 MHz

ANSWER: D

A receive channel frequency is872.4 MHz. To develop an 82.2MHz IF, the frequency synthesizer

must supply an LO signal ofA. 790.2 MHzB. 827.4 MHzC. 954.6 MHzD. 967.4 MHzNote: The LO frequency is usuallyhigher than the receive frequency.

ANSWER: C

The output power of a cellularradio is controlled by the

A. user or callerB. cell siteC. called party

D. MTSOANSWER: D

When the signal from a mobilecellular unit drops below a certainlevel, what action occurs?

A. The unit is handed off to acloser cell.B. The call is terminated.C. The MTSO increases power

level.D. The cell site switches antennas.

ANSWER: A

In a cellular radio, the duplexer is aA. ferrite isolatorB. waveguide assemblyC. pair of TR/ATR tubesD. pair of sharp bandpass filters

ANSWER: D

The time from the transmission ofa radar pulse to its reception is0.12 ms. The distance to thetarget is how many nautical miles?

A. 4.85 nmiB. 9.7 nmiC. 11.2 nmiD. 18.4 nmi

ANSWER: B

The ability of a radar to determinethe bearing to a target dependsupon the

A. antenna directivityB. speed of lightC. speed of the targetD. frequency of the signal

ANSWER: A


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The pulse duration of a radarsignal is 600 ns. The PRF is 185pulses per second. The duty cycleis

A. 1.1 percent

B. 5.5 percentC. 31 percentD. 47 percent

ANSWER: A

The Doppler effect is used toproduce modulation of which typeof radar signal?

A. pulseB. CW

ANSWER: B

The Doppler effect allows whichcharacteristic of a target to bemeasured?

A. distanceB. azimuthC. altitudeD. speed

ANSWER: D

The Doppler effect is a change inwhat signal characteristicproduced by relative motionbetween the radar set and atarget?

A. amplitudeB. phaseC. frequencyD. duty cycle

ANSWER: C

The most widely used radartransmitter component is a

A. klystronB. magnetronC. TWTD. power transistor

ANSWER: B

Low-power radar transmitters andreceiver Los use whichcomponent?

A. GaAs FETB. magnetron

C. Gunn diodeD. klystron

ANSWER: C

What component in a duplexerprotects the receiver from the high-power transmitter output?

A. waveguideB. bandpass filterC. notch filter

D. spark gapANSWER: D

Most radar antennas use aA. dipoleB. broadside arrayC. horn and parabolic reflectorD. collinear array

ANSWER: C

The most common radar display istheA. A scanB. color CRTC. liquid-crystal displayD. plan position indicator

ANSWER: D

A radar antenna using multipledipoles or slot antennas in a matrix

with variable phase shifters iscalled a(n)A. A scanB. phased arrayC. broadsideD. circular polarized array

ANSWER: B


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Police radars use whichtechnique?

A. pulseB. CW

ANSWER: B

Which of the following is a typicalradar operating frequency?

A. 60 MHzB. 450 MHzC. 900 MHzD. 10 GHz

ANSWER: D

The TV signal uses which types ofmodulation for picture and sound

respectively?A. AM, FMB. DSB, FMC. FM, AMD. AM, DSB

ANSWER: A

If a TV sound transmitter has acarrier frequency of 197.75 MHz,the picture carrier is

A. 191.75 MHzB. 193.25 MHzC. 202.25 MHzD. 203.75 MHz

ANSWER: B

The total bandwidth of an NTSCTV signal is

A. 3.58 MHzB. 4.5 MHz

C. 6 MHzD. 10.7 MHzANSWER: C

What is the total number ofinterlaced scan lines in onecomplete frame of a NTSC U.S.TV signal?

A. 262 B. 525C. 480D. 625

ANSWER: B

What keeps the scanning processat the receiver in step with thescanning in the picture tube at thereceiver?

A. nothingB. color burstC. sync pulsesD. deflection oscillators

ANSWER: C

What is the black-and-white ormonochrome brightness signal inTV called?

A. RGBB. color subcarrierC. Q and ID. luminance Y

AN

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