mberofsamples/timeresultinginavisuallyunstabledisplay.TheactualtriggerintervalshouldbeonecompletecycleforachirpsignalasindicatedinFig.c.Havingdonethistherepeatedchirpsignalforthistimedurationwillbedisplayedwithoutanyoverlappingcomponentsaslongastheentiretimeperiodisdisplayed.ToobservetheshortcomingsexperimentallyindisplayofcomplexsignalsontheoscilloscopeTektronixdualchannelsignalgeneratorAFG-(MS/srequencyandtheamplitedeonlyvarieswithtimethroughoutthesignaldefinition.Ontheotherhand,complexsignalscanbedefinedinthiscontextassignalsinwhichalltheparametersvary.Fig.showsatypicalcomplexsignali.e.LinearChirp.Variationofamplitudeandfrequencywithtimecaneasilybeunderstoodbyhavingalookatthesignal.Thisrequiresavisuallystabledisplayofsignal.Thecomplexsignalofferschallengesf'oracquisition,displayananalysis.EventheconventionalmodernageDSOisnotcapableofdisplayingandanalyzingcomplexsignalsbecausetheseinstrumentsemploysimpletriggeringtechniquelikeleveltrigger.TheconventionaltechnniqueofvoltagetriggerapparentlyfailswhencomplexsignalslikechirpareanalyzedonDSO.Thisisduetotheveryfactthattheseinstrumentsconsiderchirpasaconventionalsinewaveandtriggerforeachcycleofthesinewaveinsteadoftriggeringforthecompletechirpcycle.ThisanalysisofthechirpsignalasseveralsinewaveformsofdifferentfrequenciesleadstheDSOtodisplaythemassinusoidsinquicksuccession.Asthisrapidchangeoccuesataveryhighrateandbecauseofhumaneyenotregisteringeventsoccurringfasterthan/thofasecondthedisplayappearsasseveraloverlappedsinewaves.Intherecentwork[],anewtriggeringtechniquewasproposedforthecomplexsignalsbasedonWHD.Subsequentsectionspresentthesolutiontotheproblem.ForanalysisofthecomplexsignalsinfrequencydomainJFFAtechniqueisutilizedandimplemented[-].DSOusestheleveltriggertodisplaythewaveformappliedtoit.Thisleadstotriggerintervalandthenumberofsamplesforthistriggerintervaliscomputedandthesenumbersofsamplesaredisplay.TheDSOconsiderstheintervalasthefundamentaltimeperiodofthewholewaveformandthustakestbatmuchsamplesfromitsbufferandstartsdisplayingitinquicksuccession.Withsimplewaveformlikeasinewave,leveltriggercanachievestabledisplaybecausetriggerintervalcontainssamenumberofcycles.ThisisshowninFig.a.NowforthecomplexsignalasshowninFig.b,leveltriggeringproducesatriggerintervalhavingvariablenumberofcyclesforthesamenumberofsamples/timeresultinginavisuallyunstabledisplay.TheactualtriggerintervalshouldbeonecompletecycleforachirpsignalasindicatedinFig.c.Havingdonethistherepeatedchirpsignalforthistimedurationwillbedisplayedwithoutanyoverlappingcomponentsaslongastheentiretimeperiodisdisplayed.ToobservetheshortcomingsexperimentallyindisplayofcomplexsignalsontheoscilloscopeTektronixdualchannelsignalgeneratorAFG-(MS/s。在某些情况下，被运用到了信号中。STFT是傅里叶变换是一种改良形式。在这种技术中，信号与一个窗口功能和它产品傅立叶变换是多样性（）。[()()]jwtSTFTxtwtedt()这背后技术主要原则是窗口函数（宽）分解成小片段有限持续信号。在这些片段中信号频率分量被假定为常数。通过计算这部分傅立叶变换频率对比，得到振幅信息。然后，窗口被移动到另一个片段，通过由具有与前面给予该段频率成分相同时间段转移，因此，不同时间间隔频率有时间频率关系。然而，这个技术有一个劣势，窗口功能大小是固定，因此STFT对低、高频率有相同分辨率。解决方法是确定由哪一个能确定时间或频率信息。一般认为一个较大窗口带来更好频率分辨率，一个小窗口带来更好时间分辨率。因此，这取决于用户想要是频率还是时间分辨率。即使有一个需要改变方法，用户必须做同样手动操作。为了解决这个方法问题，引进了一个更先进技术--小波变换。通过这个窗口大小可以改变，使用比例参数答对于小波变换方程如下：(,)()()tbWTabxtdtaa（）a为比例参数，b是平移参数，x（t）是一个用于分析信号，是小波函数，小波函数x（t）是被称为母波，规模和时间改变是子波。不同大小这些子波在不同频率下有提供不同频率和时间方法。尺度参数a代表是成反比频率组成部分。因此，对于频率成分来说，规模值是成反比。最初，有规模小波函数a=，被置于开始信号上。小波变换，因此该段频率分量。然后，小波函数移动到b步骤和小波变换为这个段计算。这程序是一直持续到信号结束。因此，小波变换a=时，直到结束前所有信号计算出来了。同样，小波函数再次放置在信号开始，但对变化规模值A该过程一直持续到各尺度小波和时间步长组合变换已计算。它可以观察到小波变换计算会导致大量冗余。为了减少冗余，规模和时间值步骤可以连接使用二进采样。a=和b=k'，其中n和k是整数。这会减少冗余，这就是所谓离散小波变换（DWT）。四.实施一个数据采集卡虚拟仪器设计和编程环境中LabVIEW发展。这个虚拟仪器具有智能软件触发能力，就像上文描述复杂波形附加调频。在虚拟仪器设计中主要决定因素是：选择数据采集卡，而且同样重要是，选择仪器应该提供功能。该数据采集卡选择对整个仪器效率有很大影响[,]。特别是数据采集卡由价格和特性区别开来。一个低成本NIPCI-E、位、KS/s卡被选中。编程硬件是在最大采样率。一个单独问题是设计软件，在这种情况下，它是仪器设计阶段主要部分。所开发虚拟仪器主要特点是：获取和处理简单和复杂波形能力。双通道模式：该仪器是能同时显示两个输入，并可以执行两个简单数学运算。自动设置：运行智能温湿度控制器代码，重新为新信号计算触发时间间隔，从而实现稳定显示。假使两个输入不具有相同频率，A和B触发间隔液晶显示模块被发现，从而使双方渠道周期整数倍同时显示。时域测量：信号在时域被显示各种参数测量：振幅、峰峰值、均值（直流）、均方根值。频域经济学分析：数量级与频率，相位与频率和设施选择窗口函数图。基于STFT联合时频分析（JTFA）：在与分贝标绘在图与规模，窗口功能和对短时傅立叶变换分析窗长度选择，谱图。基于小波联合时频分析（JTFA）：该地块尺度尺度谱随时间步骤，如步骤和时间尺度和小波函数选择时间，频率采样参数选择。对于频域分析，数字信号处理工具包，LabVIEW软件提供了利用标准功能工具包。因此，虚拟仪器开发智能，因为它需要与违反数字存储示波器不同信号不同动作。触发实施使我们能够得到时间正确价值和稳定显示。复杂信号进行分析也可以使用这个工具。图显示了虚拟放映时间域测量仪器前面板。图显示了两个B通道关系进行分析时频附加调频信号。由于清楚地看到附加调频信号显示随时间变化频率。五．虚拟仪器开发限制为几个周期样品需要决定触发间隔。一个需要优化适当取样率及样本数进行处理。由智能温湿度控制器技术运用时间，直接与样本数量成正比，从而采样率较高采样率导致了每个周期样本数目越多。还需要计算时间取决于触发后，计算系统速度。对于大量数据（如果我们高采样率固定），智能温湿度控制器重计算算法和更多分析等特点，黄油可能溢出导致数据丢失。每次输入波形改变了用户也必须重新触发。六.结论与讨论有关与获取，显示和分析复杂信号功能虚拟仪器研制成功完成。这个仪器克服了DSOs缺陷普遍存在于实验当中，为复杂信号获得稳定展示。发展仪器成本效益和灵活性质特征，并有大量特征可供选择。对测量系统电脑。在VI开发，预计在仪器仪表领域走很长路要走。requencyandtheamplitedeonlyvarieswithtimethroughoutthesignaldefinition.Ontheotherhand,complexsignalscanbedefinedinthiscontextassignalsinwhichalltheparametersvary.Fig.showsatypicalcomplexsignali.e.LinearChirp.Variationofamplitudeandfrequencywithtimecaneasilybeunderstoodbyhavingalookatthesignal.Thisrequiresavisuallystabledisplayofsignal.Thecomplexsignalofferschallengesf'oracquisition,displayananalys外文文献ADAQcardbasedmixedsignalvirtualoscmoscopeAbstractComplexsignalsfindmanyapplicationsinSONAR,RADAR，EchoLocationSystemsandforstudyingtheresonantfrequencies.DigitalStorageOscilloscopcs(DSO)isusedthesedaysforacquisitionanddisplayofroutinesignals.Thisinstrument,foundineverymeasurementlaboratory,thoughpotentindisplayingsimpleperiodicwaveformslikesinusoidsfailswhenfrequency-varyingtimesignalsareapplied,Thisproblemsurfacesbecausetheunderlyingtechniqueofoscilloscopeusedtotriggerthewaveformdoesnotacquiescewithcomplexsignalslikechirp.Readysolutiontothisproblemisthemixedsignaloscilloscope.Thisisacostlysolutionandsmalllaboratoriescannotaffordtohavethecostlyinstruments.Inthispaper,acosteffectiveDAQcardbasedmixedsignalvirtualscilloscopeisproposedtostudythecomplexsignals.Anintelligenttechnique,WeightedHammingDistance(WHD)algorithmwasusedtoaccuratelytriggerthecomplexwaveforms.Alsoforfrequencydomainanalysis,JointTimeFrequencyAnalysis(JTFA)techniqueswereused.ALabVlEW'TMbasedvirtualinstrumentwasdesignedanddevelopedwithacapabilitytoacquire,displayandanalyzethetriggeredsignal.TheintegratedprogramminglanguageLabVIEWTMwaschosenasitoffersmanysimplereadytousefunctions.Inawaytheproposaloffersacosteffective,fastandflexiblesolutiontotreatthecomplexsignals.Theneedtocreatesuchsolutionsistheconsequenceofcostlyhardwaresystems.Thedeficiencyofconventionalhardware.Schemeforthevirtualoscilloscopeforcomplexsignalswithsomerealtimeexperimentalresultsarepresentedinthiswork.Kevywords:Virtualinstrumentation,Chirpsignal,Dataacquisition,Triggering,Complexsignals,JTFA.IntroductionForthelasttwodecadestherehasbeenatremendousprogressincomputertechnology.Measurementdomainisnolongerleftunaffected.Thewaymeasurementsarebeingdoneistotallyrevolutionized.Computerbasedmeasurementorsayvirtualinstrumentationisgraduallyreplacingthecostlybenchtopinstrumentationasitoffersflexible,fastandcosteffectivesolutions.VariousclassicalinstrumentationsystemsnamelyOscilloscope,MultimetersandSpectrumanalyzersect.arealmostphasedoutbytheircounterpartvirtualinstrumentation.Ourresearchextendsthetrendanddemonstratesthedevelopmenofthecomputerbasedmixedsignaldigitaloscilloscope.Conventionalsignalssuchasthesinusoidshaveaconstantfrequencyandtheamplitedeonlyvarieswithtimethroughoutthesignaldefinition.Ontheotherhand,complexsignalscanbedefinedinthiscontextassignalsinwhichalltheparametersvary.Fig.showsatypicalcomplexsignali.e.LinearChirp.Variationofamplitudeandfrequencywithtimecaneasilybeunderstoodbyhavingalookatthesignal.Thisrequiresavisuallystabledisplayofsignal.Thecomplexsignalofferschallengesf'oracquisition,displayananalysis.EventheconventionalmodernageDSOisnotcapableofdisplayingandanalyzingcomplexsignalsbecausetheseinstrumentsemploysimpletriggeringtechniquelikeleveltrigger.TheconventionaltechnniqueofvoltagetriggerapparentlyfailswhencomplexsignalslikechirpareanalyzedonDSO.Thisisduetotheveryfactthattheseinstrumentsconsiderchirpasaconventionalsinewaveandtriggerforeachcycleofthesinewaveinsteadoftriggeringforthecompletechirpcycle.ThisanalysisofthechirpsignalasseveralsinewaveformsofdifferentfrequenciesleadstheDSOtodisplaythemassinusoidsinquicksuccession.Asthisrapidchangeoccuesataveryhighrateandbecauseofhumaneyenotregisteringeventsoccurringfasterthan/thofasecondthedisplayappearsasseveraloverlappedsinewaves.Intherecentwork[],anewtriggeringtechniquewasproposedforthecomplexsignalsbasedonWHD.Subsequentsectionspresentthesolutiontotheproblem.ForanalysisofthecomplexsignalsinfrequencydomainJFFAtechniqueisutilizedandimplemented[-].DSOusestheleveltriggertodisplaythewaveformappliedtoit.Thisleadstotriggerintervalandthenumberofsamplesforthistriggerintervaliscomputedandthesenumbersofsamplesaredisplay.TheDSOconsiderstheintervalasthefundamentaltimeperiodofthewholewaveformandthustakestbatmuchsamplesfromitsbuffera        1外文文献ADAQcardbasedmixedsignalvirtualoscmoscopeAbstractComplexsignalsfindmanyapplicationsinSONAR,RADAR，EchoLocationSystemsandforstudyingtheresonantfrequencies.DigitalStorageOscilloscopcs(DSO)isusedthesedaysforacquisitionanddisplayofroutinesignals.Thisinstrument,foundineverymeasurementlaboratory,thoughpotentindisplayingsimpleperiodicwaveformslikesinuso

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