Week3TFMCTutorWord格式.docx

Week3TFMCTutorWord格式.docx

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5.

Digitaltransmissionproducesmoreerrorsthananalogtransmission.

6.

Newertelephonecircuits,builtduringthelastdecade,offerhigherqualitybecausetheywerebuiltusinganalogtransmission.

7.

Inamultipointcircuitconfiguration,eachcomputercanusethecircuitatthesametime.

8.

Insimplextransmission,thedataflowsinbothdirectionsatthesametime

9.

Anintercomisanexampleofhalf-duplextransmission.

10.

Theamountoftimeittakestoswitchbetweensendingandreceivinginhalf-duplextransmissioniscalledthepropagationdelay.

11.

Infull-duplextransmission,twostationscansendandreceivesimultaneously.

12.

Guidedmediareferstothetypeofmediainwhichthemessageisbroadcastthroughtheair.

13.

Coaxialcablecostslessandofferslessshieldingtoelectricalinterferencethantwistedpaircable.

14.

Fiberopticcablecarriessignalsintraditionalelectricalform

15.

Multimodefiberiscapableoflongertransmissiondistancesthansinglemodefiber.

16.

Radiodatatransmissionrequiresthateachdevicehasaradioreceiver/transmitterandusesaspecificfrequency.

17.

Microwavetransmissionsrequirealineofsightbetweenanytwopoints.

18.

Propagationdelayisnegligiblewithsatellitetransmission.

19.

Oneformofinterferencewithsatellitetransmissioniscalledraindropattenuationinwhichthetransmissionsareabsorbedbyheavyrain.

20.

FiberopticcablecanonlybeusedonLANs.

21.

Radio,infrared,microwaveandsatelliteareallexamplesofguidedmedia.

22.

Ofallthemediaavailable,fiberopticprovidesthehighesttransmissionspeeds.

23.

Codingschemesaregroupsofbitsthattranslateintothe“alphabet”ofanygivensystem.

24.

ASCIIistheleastpopularcodefordatacommunications.

25.

Thepredominantmethodoftransferringinformationinternallyinacomputerisviaparallelmode.

26.

Serialmodetransmissionismuchfasterthanparallelmodetransmission.

27.

Ethernet,acommonLANtechnology,usesManchesterencoding..

28.

Digitaltransmissionoccurswhenthesignalsentoverthetransmissionmediaconstantlyvariesamonganinfinitenumberofstates.

29.

FrequencyisthenumberofcyclespersecondandisexpressedinHertz.

30.

Amplitude,frequencyandphaseareallcharacteristicsofasoundwave.

31.

Frequencymodulationreferstothechangingoftheheightofthesoundwave.

32.

Demodulationistheconversationofananalogsignalintoadigitalsignal.

33.

“Handshaking”refersthetestingofthecircuittodeterminetheoptimumcombinationofsymbolrateandmodulationtechniquethatwillproducethehighestdatatransmissionrates.

34.

Datacompressioncanincreasethethroughputofacommunicationlink.

35.

Acodecconvertsanincomingdigitalsignaltoananalogsignalfortransmissionoverananalognetwork.

36.

Onewaytoreducequantizingerrorsistoincreasethesamplingrateoftheanalogsignal.

37.

The“localloop”referstothewiresthatrunfromthecustomerpremisestothetelephoneswitchofthetelephonecompany.

38.

Multiplexingincreasesthecostofprovisioningnetworkcircuits.

Moderate

39.

Frequencydivisionmultiplexingdividesthecircuitintoasetofdifferenttimeslots.

40.

Timedivisionmultiplexingismoreefficientthatfrequencydivisionmultiplexingbecausetheguardbandsusedinthefrequencydivisionmultiplexingornotneeded.

41.

Statisticaltimedivisionmultiplexingdoesnotrequirethecapacityofthecircuittobeequaltothesumofthecombinedcircuits.

42.

Wavelengthdivisionmultiplexingcanonlyusedwithcoppercables.

MULTIPLECHOICE

Dataisphysicallytransmittedfromonecomputerorterminaltoanotherinthe________layer.

a.physical

b.transport

c.application

d.terminal

e.datalink

ADifficulty:

Easy

____________referstothetransmissioncharacteristicsofthecircuit.

a.handshaking

b.virtualcircuit

c.bonding

d.logicalcircuit

e.physicalcircuit

DDifficulty:

Twofundamentallydifferenttypesofdataare:

a.DSLandADSL

b.asymmetricandsymmetric

c.MicrosoftandIBM

d.digitalandanalog

e.localareaandwidearea

Ingeneral,networksdesignedtotransmitprimarilycomputerdataarelikelytobe________,whilenetworksdesignedtotransmitvoicedataarelikelytobe________.

a.slow,fast

b.level1,level2

c.numeric,musical

d.direct,indirect

e.digital,analog

EDifficulty:

A（n）__________circuitisanothernameforamultipointconfiguration.

a.analog

b.dedicated

c.point-to-point

d.shared

e.simplex

Whichisnottrueaboutpoint-to-pointcircuits?

a.point-to-pointcircuitsarededicatedtotheuseofthetwocomputers.

b.point-to-pointcircuitsaremoreexpensivethanmultipointcircuits.

c.point-to-pointcircuitsarecalleddedicatedcircuits.

d.point-to-pointcircuitsreducetheamountofcablerequiredandusethecircuitmoreefficientlythanmultipointcircuits.

e.Point-to-pointcircuitsareusedwhenthecomputersgenerateenoughtraffictofillthecapacityofthecommunicationcircuit.

Havingaconversationwithsomeoneusingacellularphoneisanexampleof_________transmission.

a.simplex

b.full-duplex

c.half-duplex

d.analog

e.digital

BDifficulty:

Theabilitytotransmitinbothdirections,butonlyinonedirectionatatimeisanexampleof_______________transmission.

CDifficulty:

Thetwobasictypesofmediaare:

a.statisticalandfrequency

b.guidedandwireless（radiated）

c.localandwidearea

d.attenuatorandGaussian

e.duplexedandnon-duplexed

Thetypeofmediausuallyinstalledonhomesandbusinessesbythetelephonecompanyiscalled____________.

a.fiberopticcable

b.coaxialcable

c.twistedpair

d.phonecable

e.phonewire

Theearliesttypeoffiberopticsystemswere:

a.Gradedindexmultimode

b.Attenuated

c.Multimode

d.Singlemode

e.Stepmode

Anothertermfortheweakeningofasignaloverdistanceis:

a.turnaroundtime

b.propagationdelay

c.dispersion

d.insulation

e.attenuation

___________referstothespreadingofthesignalthatdifferentpartsofthesignalarriveatdifferenttimesatthedestination.

Whichofthefollowingmediacanbestwithstandharshenvironmentalconditions?

a.shieldedtwistedpair

b.unshieldedtwistedpair

c.Cat5twistedpair

d.coaxialcable

e.fiberopticcable

Microwavetransmission:

a.isatypeofhighfrequencyradiocommunication

b.requiresaclearline-of-sightpath

c.istypicallyusedforlongdistancedatatransmission

d.doesnotrequirethelayingofanycable

e.alloftheabove

______________referstothetimeittakesforasignaltotravelfromsendertorecipient（highlyexaggeratedwithsatellitetransmission）.

a.Line-of-sighteffect

b.Multimodeindex

c.Saturationeffect

d.Raindropattenuation

e.Propagationdelay

Whichofthefollowingisnotanimportantfactortoconsiderwhenselectingmediatobeusedinanetwork?

a.prestigevalueofthetypeofmedia

b.typeofnetwork

c.cost

d.transmissiondistance

e.security

Whichofthefollowingmediaistheleastsecure?

a.coaxialcable

b.unshieldedtwistedpair

c.shi