數(shù)據(jù)采集技術(shù)（DAQ）

DataAcquisitionTechniques林君jlin@Tel:8502473數(shù)據(jù)采集功能

ADCDACcntr/timerdigitalDAQBoardAnalogI/ODigitalI/OClockI/OOnOff1-0插入式數(shù)據(jù)采集卡的優(yōu)越性靈活費(fèi)用較低性能選擇范圍大大量的軟件工具可用利用PC技術(shù)數(shù)字化技術(shù)信號(hào)分類(lèi)信號(hào)根據(jù)其所傳遞的有用信息進(jìn)行分類(lèi)信息狀態(tài)速率幅值形狀頻率SignalsAnalogDigitalOn-OffTimeDomainPulseTrainFrequencyDomainDConofft1-0-t0.985ttf數(shù)字信號(hào)開(kāi)關(guān)信號(hào)

連續(xù)脈沖信號(hào)Input:ReadanopticalencoderOutput:Generateasquarewave分辨率時(shí)鐘頻率Input:SenseaswitchclosureOutput:Closeavalve驅(qū)動(dòng)程序的功能通道數(shù)DAQ卡需要考慮的指標(biāo)onofft1-0-t數(shù)字信號(hào)調(diào)理Common-ModeVoltagesorHighVoltagesElectromechanicalRelaysorSolid-StateRelaysOpticalIsolationLoadsRequiringACSwitchingorLargeCurrentFlowSolenoidsValvesMotorsHeatersLampsPumpsElectromechanicalRelaysorSolid-StateRelaysProductionMonitoringorProcessControlProximitySwitchesLimitSwitchesThermostatsManualSwitches數(shù)字I/O模擬信號(hào)時(shí)域信號(hào)VibrationSpeechSonar分辨率采樣率AC精度觸發(fā)濾波器TemperaturePressureFlowStrainDC精度頻域信號(hào)直流信號(hào)ECGBloodpressureSingle-shoteventsChromatograph分辨率采樣率AC和DC精度觸發(fā)DAQ卡需要考慮的指標(biāo)參數(shù)0.985ttf模擬信號(hào)調(diào)理低電壓信號(hào)電流輸入/輸出RTDs

和熱敏電阻熱電偶應(yīng)變儀隔離放大噪聲濾波電流與電壓的轉(zhuǎn)換;隔離，放大，噪聲濾波隔離，放大，噪聲濾波冷端補(bǔ)償激勵(lì)電源隔離，放大，噪聲濾波激勵(lì)電壓全橋和半橋設(shè)置隔離，放大，噪聲濾波多功能I/ODemo變送器/傳感器

物理現(xiàn)象 傳感器溫度 熱電偶

RTD IC傳感器 熱敏電阻光 真空管光電傳感器聲 麥克風(fēng)力和壓力 應(yīng)變儀 壓電傳感器熱電偶價(jià)格較低，堅(jiān)固可承受高溫可迅速感知溫度的快速變化需要作冷端補(bǔ)償電壓量很小需要放大輸出非線(xiàn)性需要冷端補(bǔ)償RTDs精度比熱電偶高不需要冷端補(bǔ)償比熱電偶昂貴需要電流源非線(xiàn)性輸出，需要線(xiàn)性化2路RTDs接線(xiàn)，簡(jiǎn)單，但要考慮接線(xiàn)電阻誤差3路和4路RTD接線(xiàn)，消除了接線(xiàn)電阻誤差熱敏電阻

需要電流源或電壓源激勵(lì)非線(xiàn)性化強(qiáng)烈，需要線(xiàn)性化敏感度高電阻高應(yīng)變片需要電壓源需要橋式電路設(shè)置非線(xiàn)性化輸出，需要線(xiàn)性化DAQ卡的前端信號(hào)調(diào)理模塊

SignalConditioningExtensions

forInstrumentation（SCXI)

SCXI選擇傳感器和信號(hào)熱電偶RTDs熱敏電阻應(yīng)變儀電壓信號(hào)

微伏，毫伏，伏電流信號(hào)

4—20mA,0—20mA數(shù)字信號(hào)信號(hào)調(diào)理多路復(fù)用放大隔離濾波傳感器激勵(lì)冷端補(bǔ)償SCXI的其它特性可擴(kuò)展，最多到3,072通道緊湊，在7英寸空間可達(dá)384個(gè)通道靈活，可以和最新的采集卡，軟件，和計(jì)算機(jī)配合工作高速，和E系列的采集卡配合掃描速度達(dá)33KHz設(shè)置方便結(jié)構(gòu)開(kāi)放DemoA/D分辨率Codewidth=smallestdetectablechangeinvoltage=AD的輸入范圍增益*2nn=#ofADCbits

16-bitADC3-bitADCAmplitudecodewidthTime02010012014040608010.009.757.506.255.003.752.501.250111110100011010001000A/D采樣率Nyquist

原理采樣率>2倍的最高頻率AdequatelysampledAliasedduetoundersampling多通道采集采集模式通道設(shè)置掃描順序增益范圍單端/差分輸入單極/雙極連續(xù)掃描同步采樣間隔掃描Straingauge1Straingauge2Battery1Battery2TempPressureDemo實(shí)時(shí)系統(tǒng)集成總線(xiàn)RTSI

Real-TimeSystemsIntegrationBusRTSI在板卡之間連接時(shí)鐘和觸發(fā)信號(hào)完成數(shù)據(jù)采集的同步操作在DSP卡串行傳輸數(shù)據(jù)觸發(fā)軟件觸發(fā)STARTTRIG*InputofMIOBoardEdgeInitiatesAcquisition

TTLSignalLevelandSlopeofAnalogSignalInitiatesAcquisition

LevelandSlopeofAnalogSignalRetrievesAcquisition條件獲取(軟件)由AIBufferRead設(shè)定AIRead調(diào)用AIBufferRead模擬觸發(fā)數(shù)字觸發(fā)Demo應(yīng)用軟件接口軟件軟件LabVIEWLabWindows/CVIComponentWorksVisualBasicC/C++...PCI-MIO-16E-1DAQ卡NI-DAQ要求:可以所有采集卡的功能向下兼容通用的API功能齊全的設(shè)置工具方便易用DAQ的軟件接口NI-DAQApplicationSoftwareDemo軟件開(kāi)發(fā)平臺(tái)選擇VirtualBench

Ready-to-RunVirtualInstrumentsVirtualInstrumentsScopeDynamicsignalanalyzerArbitrarywaveformgeneratorFunctiongeneratorDMMDataloggerDemo軟件開(kāi)發(fā)平臺(tái)GraphicalProgrammingVisualC++LabWindows/CVIVisualBasicGraphicalProgramming

LabVIEWEmpoweringtechnologyNaturalflowchartnotationEliminatessyntacticaldetailsReducesdevelopmenttimeRapidprototypingSelf-documentingIntuitiveandeasytolearnIdealforcodereusabilityModularityandhierarchyDemoWhatisMeasurementStudio?MeasurementHardwareWindowsVisualBasic

VisualC++InternetVisualizationAnalysisAcquisitionLabWindows/CVIMeasurementStudioMeasurementComponentsMeasurementStudio

ToolsforVisualC++CompilerintegrationIntellisense

ClassWizardVisaGPIBAnalysisUI

ControlsUtilityClassesApplicationWizardMeasurementclassesAcquisitionAnalysis

UserinterfacethroughActiveXUtilityclassesDataobjectsData

ObjectMeasurementStudio

ToolsforVisualBasicMeasurementandautomationActiveXcontrolsAnalysisUIDAQNetworkGPIBSerialLabWindows/CVIANSICStandardLanguageCompilerEditorDebuggerOpenSystem

Built-in

Instrumentation

LibrariesI/O

(GPIB,VXI,

DAQ,Serial,

IMAQ,etc)Analysis

DataSocket

ActiveX TCPGUI

ProductivityTools

forfasterdevelopmentCodeGenerationToolsInteractiveExecution

StandardANSIC

LanguageOpen,powerfulMultithreadedDemo數(shù)據(jù)采集的基本原理(3.1)數(shù)據(jù)采集的基本原理數(shù)據(jù)采集的基本原理采樣定理的推導(dǎo)采樣定理的推導(dǎo)采樣定理的推導(dǎo)采樣定理的推導(dǎo)采樣率的確定數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)MUX切換PGA切換S/HA/D開(kāi)始工作A/D轉(zhuǎn)換完成讀取數(shù)據(jù)存儲(chǔ)數(shù)據(jù)循環(huán)至結(jié)束數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)浮點(diǎn)放大數(shù)據(jù)采集系統(tǒng)設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)數(shù)據(jù)采集系統(tǒng)的設(shè)計(jì)設(shè)計(jì)一個(gè)四路數(shù)據(jù)采集系統(tǒng)各路輸入信號(hào)性能要求第一路：?jiǎn)未巫枘嵴袷幉ㄐ危掷m(xù)時(shí)間為0.4-1s，阻尼振蕩頻率f0=5