雨课堂学堂在线学堂云Signals and Systems(北京交通大学)单元测试考核答案

第1题第2题第3题第4题第5题第6题第7题Determinewhetherthefollowingsignalsareperiodicsignals.Ifyes,determineitsperiod.ABCD第8题Determinewhichofthefollowingsignalsareenergysignals,whicharepowersignals,ornoneofthem.ABCD第9题Theinput-outputrelationshipsofthesystemsareasfollows,wherex(t)andy(t)aretheinputandoutputofthecontinuous-timesystems,y(0)areinitialstates,x[k]andy[k]arethe

inputandoutputofthediscrete-timesystems,y[0]areinitialstates.Determinewhetherthesesystemsarelinearsystems?ABCD第10题Determinewhetherthefollowingsystemsaretime-invariantsystems,why?Wherex(t)andx[k]areinputsignals,y(t)andy[k]arezero-stateresponses.ABCD第1题Whichofthebelowdeterministicsignalsisacontinuous-timeenergysignal().ABCD第2题Givenaperiodiccontinuous-timesignal,whatisthesignal'speriodandtheaveragepowerP()?ABCD第3题Giventhebelowrelationshipsbetweenthevoltageandthecurrent,pleasepickthesystemthatistime-variant(

).ABCD第4题Belowarefourdiscrete-timesystemandtherelationshipbetweentheinput,,theoutput,,andtheinitialstate,isgivenforeachofthesystems,whichisnotalinearsystem()?ABCD第5题Giventherelationshipbetweentheinput,theoutput,andtheinitialstate,whichofthesystemsisalinearsystem()?ABCD第6题Whichofthebelowsystemisatime-invariantsystem?Giventhatoristheinputofthesystemandandistheoutput().ABCD第7题Giventhedifferenceequationofadiscrete-timesystemis,thenthesystemis().ACausal,lineartime-invariantsystemBCausal,lineartime-varyingsystemCNon-causal,lineartime-invariantsystemDNon-causal,nonlineartime-invariantsystem第8题Foralinearcontinuous-timesystem,whentheinitialstateisandtheinputsignalis,theoutputis;whentheinitialstateisandtheinputsignalis,theoutputis,thenwhatistheoutputwhentheinitialstateisandtheinputsignalis()?ABCDExerciseforChapter2第1题第2题第3题第4题第5题第6题第7题第8题Determineeachoffollowingformulaswithpropertyofimpulsesignal.ABCD第9题Considerthewaveformofsignalx(t)isshowninFigure2，sketcheachoffollowingsignals.A

x(-2t-5)；Bx(t)+u(t)；Cx(t)u(1-t)；D

x'(t)第10题Given

twosequencesand

,pleasesketchthewaveformsofthefollowingsequences.

ABCDHomeworkforChapter2第1题Asinusoidalsignalcanberepresentedbyusingimaginaryexponentialsignalas().ABCD第2题Whichoneofthebelowdescriptionsoftheimaginaryexponentialsignalisnotcorrect().ABoththeimaginaryexponentialsignalandthesinesignalareperiodicsignalswiththefundamentalperiodof.BTheimaginaryexponentialsignalcanberepresentedas.CBoththeimaginaryexponentialsignalandthesinesignalcanbelinearlyrepresentedbytheothersignal,andthus,theyhavethesameproperties.DThegreaterthe,thehighertheoscillationfrequencyoftherealandimaginarypartsoftheimaginaryexponentialsignal.第3题

Given

thewaveformofasignal,

asshownbelow,itcanberepresentedas(

).ABCD第4题=().ABCD第5题Thevalueoftheintegralis().A0B4C-4D2第6题WhichoneofthebelowrelationsisWRONG().ABCD第7题WhichoneofthebelowdescriptionsoftheimaginaryexponentialsequenceisWRONG().ATheimaginaryexponentialsequenceisnotnecessarilyperiodic.BTheimaginaryexponentialsequenceandsinusoidalsequencescanrepresenteachotherusingtheEuler'srelation.CTheimaginaryexponentialsequencecanbeobtainedbysamplingfromthecontinuous-timesignal,therefore,theyshouldhavethesameperiod.DTheamplitudeoftheimaginaryexponentialsequencemaynotincreaseastheangularfrequencyincrease.第8题WhichoneofthebelowrelationsisWRONG()?ABCD第9题

Given

thewaveformofsignalshownbelow,thesignalcanberepresentedbyusingandas(

).ABCD第10题

Given

thewaveformofasignalshownbelow,thewaveformofx′(t)

shouldbe(

).ABCD第11题

The

waveformofasignalshownbelow,whatisthewaveformof(

).ABCD第12题If,,then=().ABCD第13题

Given

thewaveformofthesignalshownbelow,whichoneoftherepresentationofiswrong(

).ABCD第14题Ifadiscrete-timesequence,thenwhichofthefourexpressionsisNOTtheevencomponentof().ABCD第15题Asinusoidalsignalcanberepresentedbyusingimaginaryexponentialsignalas().ABCD第16题Whichoneofthebelowdescriptionsoftheimaginaryexponentialsignalisnotcorrect().ABoththeimaginaryexponentialsignalandthesinesignalareperiodicsignalswiththefundamentalperiodof.BTheimaginaryexponentialsignalcanberepresentedas.CBoththeimaginaryexponentialsignalandthesinesignalcanbelinearlyrepresentedbytheothersignal,andthus,theyhavethesameproperties.DThegreaterthe,thehighertheoscillationfrequencyoftherealandimaginarypartsoftheimaginaryexponentialsignal.第17题Giventhewaveformofasignal,asshownbelow,itcanberepresentedas().ABCD第18题=().ABCD第19题Thevalueoftheintegralis().A0B4C-4D2第20题WhichoneofthebelowrelationsisWRONG().ABCD第21题WhichoneofthebelowdescriptionsoftheimaginaryexponentialsequenceisWRONG().ATheimaginaryexponentialsequenceisnotnecessarilyperiodic.BTheimaginaryexponentialsequenceandsinusoidalsequencescanrepresenteachotherusingtheEuler'srelation.CTheimaginaryexponentialsequencecanbeobtainedbysamplingfromthecontinuous-timesignal,therefore,theyshouldhavethesameperiod.DTheamplitudeoftheimaginaryexponentialsequencemaynotincreaseastheangularfrequencyincrease.第22题WhichoneofthebelowrelationsisWRONG()?ABCD第23题Giventhewaveformofsignalshownbelow,thesignalcanberepresentedbyusingandas().ABCD第24题Giventhewaveformofasignalshownbelow,thewaveformofshouldbe().ABCD第25题Thewaveformofasignalshownbelow,whatisthewaveformof().ABCD第26题If,,then=().ABCD第27题Giventhewaveformofthesignalshownbelow,whichoneoftherepresentationofiswrong().ABCD第28题Ifadiscrete-timesequence,thenwhichofthefourexpressionsisNOTtheevencomponentof().ABCDExerciseforChapter3第1题第2题第3题第4题第5题第6题第7题第8题HomeworkforChapter3第1题Ifthezero-state(ZS)responseofaC-Tlineartime-invariant(LTI)systemtotheunitstepsignalis,

thentheimpulseresponseofthesystemis(

).ABCD第2题Iftheimpulseresponseofdiscrete-time(D-T)LTIsystemis,thentheunitstepresponseofthesystemis().ABCD第3题AssumingthattheinitialstateofaC-TLTIsystemisnotzero,iftheinputis,thefullresponseofthesystemis,now,iftheinputincreasesto2,thefullresponseofthesystemwill().Aincreasesto2Bincreasesbutlessthan2CremainasDchangesbutnoneoftheabovearecorrect第4题Thedifferentialequationofa2ndorderC-TLITsystemis,andtheinitialstateincludesy(0−)

and

y′(0−),thenthezero-input(ZI)responseis(

).ABCD第5题Thedifferentialequationofa2ndorderC-TLTIsystemis,thentheformoftheimpulseresponseofthesystemis().ABCD第6题If,then().ABCD第7题WhichoneofthebelowsignalisNOTequalto().ABCD第8题

ForaC-TLTIsystem,theinputandtheimpulseresponseofthesystemareshownbelow,thenthevalueoftheZSresponseofthesystematt=1is(

).A-2B-1C0D1第9题TheimpulseresponseofaC-TLTIsystemis,iftheinput,thentheZSresponseofthesystemis().ABCD第10题The

differentialequationofaC-TLTIsystemis

y″(t)+5y′(t)+4y(t)=2x′(t)+5x(t),,Iftheinitialstateofthesystemisnotzero,theinput,andthefullresponse,thenthenaturalresponseofthesystemis(

).ABCD第11题IfthedifferenceequationofaD-TLTIsystemis,Andtheinitialstateofthesystemincludes=1,,thenthezero-inputresponseofthesystemis().ABCD第12题ThedifferenceequationofaD-TLTIsystemis,Thentheimpulseresponseofthesystemis().ABCD第13题TheimpulseresponseofaD-TLTIsystemis,

theinput,thenZSresponseofthesystemat=3(

).A2B3C4D5第14题TheimpulseresponseofaD-TLTIsystemis,,Iftheinputis,thentheZSresponseofthesystemis().ABCD第15题GiventhatthedifferenceequationofaD-TLTIsystemis,,iftheinitialstateofthesystemisnotzero,theinputis,andthefullresponse,thenthetransientresponsethesystemis().ABCD第16题TheimpulseresponsesoftwoC-TLTIsystemsareand,respectively,ifthesetwosystemsareinparallelconnection,thentheimpulseresponseoftheoverallsystemis().ABCD第17题

TheoverallimpulseresponseoftheD-TLTIsystemshownbelowis(

).ABCD第18题Theimpulseresponseofamovingaveragesystemwithis,then,thesystemis().Anon-casual、stableBcasual、unstableCnon-casual、unstableDcasual、stableHomeworkforChapter4第1题ThereasonforGibbsphenomenonisthatonlyalimitednumberofFourierseriestermsareusedtorepresentperiodicsignals().A√B×第2题Thefasterthesignalinthetimedomainchanges,themorethehigh-frequencycomponentthesignalhas().A√B×第3题Ifthemaximumfrequencyofagivensignal,x(),isHz,andthesamplingfrequency,thenthesampledsignalwillhavealiasing().A√B×第4题Ifasignalisshiftedinthetimedomain,thenitsamplitudespectrumwillremainthesamewhileitsphasespectrumwillhavephaseshift().A√B×第5题Ifacontinuous-timesignalisextendedinthetimedomain,thenitwillhavemorehigh-frequencycomponents().A√B×第6题Nomatterforcontinuousordiscrete-timesignals,thespectrumofaperiodicsignalisalwaysdiscreteandthespectrumofanon-periodicsystemisalwayscontinuous().A√B×第7题Ifaperiodiccontinuous-timesignal,,ispowersignal,thenitsFouriertransformdoesnotexist().A√B×第8题Thesumoftheaveragepoweroftheharmonicsinsidetheeffectivebandwidthtakesthemajoritypartoftheaveragepowerofthewholesignal().A√B×第9题Ifthespectrumofanon-periodicsignalis,thentheyareinone-to-onecorrespondence().A√B×第10题Foranycontinuous-timesignal,theamplitudespectrumisevenwhilethephasespectrumisodd().A√B×第11题

The

waveformofacontinuous-timesignalisshownbelow,whatfrequency

componentsdoesthesignalhave(

)?ACosinecomponentsforallharmonicBSinecomponentsforallharmonicCSinecomponentsforoddharmonicDCosinecomponentsforoddharmonic第12题

Given

thespectrumofacontinuous-timesignalisshownbelow,then,theperiodic

signal=(

).ABCD第13题

For

aperiodicsignalshownbelow,theDCcomponentis(

).A0B2C2.5D4第14题Theaveragepowerofperiodiccontinuous-timesignalis().A6B6.5C8D8.5第15题The

spectrumofanon-periodiccontinuous-timesignalis().Acontinuousandnon-periodicBcontinuousandperiodicCdiscreteandnon-periodicDdiscreteandperiodic第16题TheFouriertransformofsignalis().ABCD第17题Givenasignal,thevalueofthespectrumat,is().A0B4C8D16第18题Ifthebandwidthofthebandlimitedsignalis,thenthebandwidthofthesignalis().A2BCD4第19题Thehighestangularfrequencyofthespectrumofonesignalis,andthehighestangularfrequencyofthespectrumofasecondsignalis,then,thehighestangularfrequencyofthesignalis().ABCD第20题

A

signalisshownbelow,thespectrumofsignalis(

).ABCD第21题Ifthehighestfrequencyofarealsignalis,thenthehighestfrequencyofthesignalis().A100HzB150HzC200HzD400Hz第22题Theenergyofthesignalis().ABCD第23题

If

theFouriertransformofthesignalshowninFigure(a)is,

thentheFouriertransformofthesignalinFigure(b)is().(a)

(b)ABCD第24题Thespectrumofthesignalis,thenthespectrumofthesignalis().ABCD第25题Ifthespectrumofarealcontinuous-timesignalis,thenthespectrumofsignalis().ABCD第26题Givenavoicesignal,ifwetransformthesignaltoanewsignal,whatwillthenewsignalbedifferentfromtheoriginalsignal().AThelengthofwillbelongerandthepitchwillbehigherBThelengthofwillbelongerandthepitchwillbelowerCThelengthofwillbeshorterandthepitchwillbehigherDThelengthofwillbeshorterandthepitchwillbelower第27题Foraperiodicdiscrete-timesequence,thespectrumis,ifthespectrumofanotherperiodicdiscrete-timesignalis,thenthevaluesofthesequenceatare().ABCD第28题Ifthespectrumofadiscretesequenceis,thenthespectrumofsignalis().ABCD第29题Given

atime-limitedsequence,

thenthevalueofthespectrumx(ejΩ)atΩ=0

is=(

).A1B2C3D5第30题Assumingthatthefrequencyofthesignalis,ifonesamplesthesignal,toavoidaliasing,whatisthemaximumofthesamplinginterval()?ABCD第31题Whichofthebelowstatementsiscorrect,intermsofthesamplingtheoryinthetimedomain()?ATheshorterthesamplinginterval,thebetter.BThesamplingfrequencymustbegreaterthanorequaltothemaximumfrequencytimestwo.CItisnotnecessarythatthesampledsignalcontainsalltheinformationofthecontinuous-timesignal.DDiscretizationinthetimedomaincorrespondstoperiodizationinthefrequencydomain.第32题

The

spectrumofacontinuous-timesignalis

x(jω)

,

showninthefigurebelow,ifonesamplesthesignalatasamplingfrequencytoobtainadiscrete-timesignal,

thenthespectrumofthediscrete-timesignalis

x(ejΩ),

giventhat,

whichofthebelowspectrumis

x(ejΩ)?

(

).ABCDHomeworkforChapter5第1题ThedifferentialequationofacausalandstableC-TLTIsystemis,then,thefrequencyresponseofthesystemis().ABCD第2题TheunitimpulseresponseofaC-TLTIsystemis,thenthefrequencyresponseofthesystemis().ABCD第3题TheunitimpulseresponseofaC-TLTIsystemis,thefrequencyresponseofthesystem=().ABCD第4题ThefrequencyresponseofaC-TLTIsystemis,iftheinputis,thentheZSresponseofthesystemis().ABCD第5题ThefrequencyresponseofaC-TLTIsystemis,theZSresponseofthesystemtotheinputis().ABCD0.2第6题GiventhatthefrequencyresponseofaC-TLTItransmissionsystemisthesystemis().AadistortionlesstransmissionsystemBatransmissionsystemwithadistortionlessamplituderesponsebutadistortedphaseresponseCatransmissionsystemwithadistortionlessphaseresponsebutadistortedamplituderesponseDatransmissionsystemwithdistortedamplitudeandphaseresponses第7题Thefrequencyresponseofanidealanaloglow-passfilterisIftheinputsignalis,thentheZSresponseofthesystem=().A1B2CD第8题IftheunitimpulseresponseofaC-TLTIsystemis,thentheamplituderesponseofthesystemis().Alow-passBhigh-passCband-passDband-stop第9题ThedifferenceequationofaD-TLTIsystemis,thenthefrequencyresponseofthesystem=().ABCD第10题TheunitimpulseresponseofaD-TLTIsystemis,thenthefrequencyresponseofthesystem=().ABCD第11题TheunitimpulseresponseofaD-TLTIsystemis,iftheinputis,thentheoutputofthesystemis=()ABCD第12题TheunitimpulseresponseofaD-TLTIsystemis,theamplituderesponseofthesystemis().Alow-passBhigh-passCband-passDband-stop第13题AnAMradiostationisbroadcastingamusicalsignalwiththehighestfrequencyof10kHz,giventhatthestationusesadouble-bandamplitudemodulationandthefrequencyofthecarrieris800kHz,thentheupperandlowercutofffrequenciesare().A790kHz,810kHzB790kHz,800kHzC800kHz,810kHzD800kHz,820kHz第14题

Shown

intheblowdiagramisaC-Tsystem,ifthespectrumoftheinput

signalis,the

spectrumoftheoutputis(

).ABCDHomeworkforChapter6第1题x(t)=2r(t−1)−3r(t−2)+r(t−4),

theunilateralLaplacetransformis(

).ABCD第2题,

thentheinitialvalueof,is(

).A1B0CdoesnotexistD-1第3题,

thenthefinalvalueof,is().A1B0CdoesnotexistD-1第4题,theninverseLaplacetransformof,is().ABCD第5题TheimpulseresponseofaC-TLTIsystemis.Theinputas,whenanalyzingthezero-stateresponseinthecomplexfrequencydomain,whichofthebelowstepsiswrong?().AFindtheunilateralLaplacetransformof,BFindtheunilateralLaplacetransformof,CFindthezero-stateresponseinthecomplexfrequencydomainDTaketheinverseLaplacetransformof,tofindthezero-stateresponseinthetimedomain第6题Given

thattheregionofconvergence()ofthebilateralLaplace

transformof,is,is(

).

ABCD正确答案：C第7题Thetransferfunctionsoftheidealintegratoranddifferentiatorare().AB1,C,1D,第8题IfthetransferfunctionofaC-TLTIsystemis,thenthesystemis()ALowpassBHighpassCBandpassDBandstop第9题Thezero-stateresponseofaC-TLTIsystemtoaninput,is,thenthetransferfunctionofthesystemis().ABCD第10题ThetransferfunctionofaC-TLTIsystemis,thenthesystemis().ACausalandstableBNon-causalandstableCCausalandunstableDNon-causalandunstable第11题AcausalC-TLTIsystemis,thenthetransferfunctionandtheunitinpulseresponseare().A,B,C,D,第12题

The

zero-poleplotofaC-TLTIsystemisshownbelow,and,Then

theunitimpulseresponseofthesystemis(

).ABCD第13题

The

blockdiagramofacausalC-TLTIsystemisshownbelow,thenthe

transferfunctionofthesystemis().ABCD

第14题ForacausalC-TLTIsystem,iftheinputis,thenthezero-stateresponseis,nowiftheinputischangedto,thecorrespondingzero-stateresponsewillbechangedto.Thentheinputis().ABCD第15题

If

thebelowcausalC-TLTIsystemisstable,whatconditionshouldsatisfy?(

).ABCD第16题AcausalC-TLTIsystemisandtheinitialstateandtheinput,whencalculatingthesystem'szero-inputandzero-stateresponsesandtheunitimpulseresponse,whichofthebelowstepsiswrong?().ATakeunilateralLaplacetransformonbothsidesofthedifferentialequation,BCalculatethezero-inputresponseCCalculatethezero-stateresponseDCalculatetheunitimpulseresponseHomeworkforChapter7第1题Ifthez-transformofis,thenis().ABCD第2题Iftheunilateralz-transformofis,thenis().ABCD第3题Iftheunilateralz-transformofis,thentheunilateralz-transformandtheregionofconvergence()ofis().ABCD正确答案：C第4题Iftheunilateralz-transformofis,then

x[∞]()Ais0Bis1Cis∞Ddoesnotexist第5题Iftheunilateralz-transformofis,,thenis()A0B1C-1D∞第6题Given,theinversez-transformofis()ABCD第7题Thezero-stateresponseofaD-TLTIsystemtotheinputis,thenthetransferfunctionofthesystemis()ABCD第8题IftheunitimpulseresponseofaD-TLTIsystemish[k]=δ[k]−(14)ku[k],thenthedifferenceequationofthesystemis().ABCD第9题Thezero-stateresponseofaD-TLTIsystemtoaunitstepsequenceu[k],whichalsocalledtheunitstepresponse,is

g[k]=(12)ku[k],thenthezero-stateresponseofthesystemtotheinputx[k]=(13)ku[k],

is