ECE 210 Laboratory Experiments in LabVIEWUniversity of Illinois.docx

ECE 210 Laboratory Experiments in LabVIEWUniversity of Illinois.docx

《ECE 210 Laboratory Experiments in LabVIEWUniversity of Illinois.docx》由会员分享，可在线阅读，更多相关《ECE 210 Laboratory Experiments in LabVIEWUniversity of Illinois.docx（25页珍藏版）》请在冰豆网上搜索。

ECE210LaboratoryExperimentsinLabVIEWUniversityofIllinois

ECE210LaboratoryExperimentsinLabVIEW

by

JesseChen

and

YangZheng

ECE345SectionH,Spring2000

SupervisedbyProfessorDavidMunson

and

T.A.ShaoHsia

5/1/2000

Project9

Abstract

ThepurposeoftheECE210laboratoryexperimentsistovisuallyrepresentlinearsystemconceptstaughtinclass.SimulatinglaboratoryexperimentsinLabVIEWinsteadofusingareal-lifesetupprovidesseveraladvantages.Theuseofcomputersimulationsreducesthepossibilityofmiswirings,improperequipmentuseorequipmentfailure.UsingaGUIbasedsimulationpackageallowsinstructorstodesigncircuitsthatbehavesimilartorealcircuitswhileprovidingcontrolsanddisplayssimilartothoseusedinrealinstruments.Also,simulationsmaybeanexcellentalternativetouniversitiesthatdonothavesufficientfundingorstaffingtoprovideacomprehensivelabenvironmenttoitsstudents.Similarly,studentstakingthecourseremotelyfromtheuniversitymayusesimulationsasanaddedlearningtool.However,simulationscan’treplacetheexperiencegainedbyseeingthedifferencesbetweentheoreticalcalculationsandrealresultsproducedinlab;orexperiencegainedbyusinglaboratoryinstruments.

TABLEOFCONTENTS

1.PROJECTOVERVIEW1

1.1Introduction1

1.2DesignSpecifications2

1.3GeneralDesignProcedures2

1.4TheAdvantagesandDisadvantagesofUsingLabVIEW2

1.5CostAnalysis3

2.LaboratoryExperiment14

2.1Lab1Overview4

2.2Lab1DesignDetails4

2.3Lab1DesignVerification5

3.LaboratoryExperiment26

3.1Lab2Overview6

3.2Lab2DesignDetails7

3.3Lab2DesignVerification9

4.LaboratoryExperiment310

4.1Lab3Overview10

4.2Lab3DesignDetails10

4.3Lab3DesignVerification10

5.LaboratoryExperiment411

5.1Lab4Overview11

5.2Lab4DesignDetails11

5.3Lab4DesignVerification12

6.CONCLUSIONS13

7.REFERENCES14

APPENDIXI.Laboratory1Figures15

APPENDIXII.Laboratory2Figures19

APPENDIXIII.Laboratory3Figures22

APPENDIXIV.Laboratory4Figures24

1.PROJECTOVERVIEW

1.1Introduction

TheECE210laboratoryteachesbasiclinearsystemconcepts,whichcanbelearnedthroughLabVIEWsimulationinsteadofcircuitry.LabVIEWisaGUIbasedsimulationenvironmentthatallowsaninstructortoquicklycreateasimulationthataccuratelyapproximatesthebehaviorofacircuit.ThebuiltincontrolsanddisplaysinLabVIEWallowthestudenttoseetheresultsofagiveninputintoalinearsystemalmostinstantaneously.Also,thestudentcanvarytheinputconditionsintothesystemtoobservechangesattheoutput.Thesimulationcanalsobeconstructedsuchthatthestudentisabletomodifyparametersofthesystem;forexample,theresistanceandcapacitanceofasimplelowpassfiltertochangethetimeconstant.

ThefollowingblockdiagramillustrateshowtheprojectfunctionsalongwithotherrequirementsintheECE210laboratory.

Figure1

Asshownbythebluearrow,ourprojectdealsmainlywiththesimulationanduserinterfaceaspectsoftheECE210laboratory.

1.2DesignSpecifications

OurprojectfocusesondesigningtheLabVIEWinterfaceforthelaboratoryexperimentsinECE210.Thefinaldesignincludesfourofthefivelaboratoryexperimentssimulatedundertheassumptionofanidealsystem.Thefifthlabexperiment,thesuperheterodynereceiver,wasnotimplemented.Timeconstraintsaswellasthefeasibilityofaccuratelyreceivinganddemodulatingaradiosignalwerereasonsforthisdecision.Eachlaboratoryexperimentconsistsofseparate“VisualInstrument”orVIfilesthatsimulateaparticularsectionoftheexperiment.Studentscanswitchfreelybetweenthesectionstosimulate“wired”circuits.Thestudentisnotallowedalterthecircuits,butthestudentisabletochangecertainparametersofthecircuit,suchasresistance,capacitance,orinputsignal.Ifthe“ContinuousRun”optionisusedinLabVIEW,thesimulationwillcontinuouslyupdatetheoutputdisplay.

1.3GeneralDesignProcedures

InitialcalculationsweredoneaccordingtothetheorypresentedintheECE210classnotes.Next,PSpicesimulationswereusedtocheckthecalculationsandprovideareasonableexpectationfortheperformanceofoursystem.ThecalculationswerethenmodifiedsothattheycouldbeinputintothedesignschematicofaLabVIEWVIfile.Aftertestingandverifyingthatthesimulationwasperformingsatisfactorily,theGUIfrontpanelwouldbebuilt.

1.4TheAdvantagesandDisadvantagesofUsingLabVIEW

AlthoughwewereapproachedwiththeideaofimplementingtheECE210laboratoryexperimentsinLabVIEWbybothProfessorMunsonandNationalInstruments,weconsideredothersoftwarepackages.AcircuitsimulationpackagesuchasPSpicewouldhavebeenanalternatechoice.ThePSpicealreadycontainsthenecessarycomponentsandtoolsforsimulatinganalogcircuits.LabVIEWontheotherhand,can’tevensimulatearesistorwithoutcalculationsandformulasfromtheinstructor.However,PSpicelacksthefriendlygraphicaluserinterfacethatLabVIEWprovides.Also,LabVIEWsimulationscanbechangedinreal-time,unlikePSpicesimulationsthathavetobepainstakinglyadjustedandre-runbeforethenewresultsappear.PSpicesimulationsmaybemoreaccuratethanourLabVIEWsimulations,butthisisn’tasimportanttousbecausetheLabVIEWsimulationsalreadysufficientlyimproveclarityoftheresults.WechosetodevelopinLabVIEWafterconcludingthattherewasnoproductthatwasclearlybetter.

However,themaindisadvantageofusingLabVIEWisthatallanalogsignalprocessingmustbeimplementeddigitally.Allsignalsandtransferfunctionsmustbecalculated,sampled,andcheckedforvalidity.Samplingratesandprocessorspeedconsiderationslimittheaccuracyofthesimulations.LabVIEWdoesprovideimportantcomponents,suchassignalgeneratorsanddigitalconvolutionfunctions.Allothernecessaryfunctionsmustbeimplementedbytheinstructorasamathematicalformula,forLabVIEWtocalculate.Forcingallsignalstobedigitallysampledlimitssomeofthepotentialofthesimulationpackage,butitdoesprovidesomeinterestingshortcutsandsolutionsforthesimulationdesigner.

1.5CostAnalysis

Description

Cost

ReferenceBooks

$75

Software

LabVIEWSoftware

（2）

$200

Labor（14weeks）

7hrs/week/person*13weeks*2persons*$33/hr*2.5

$15,015

ProjectTotal

$15,290

2.

LaboratoryExperiment1

2.6Lab1Overview

ThefirstlabgivesanintroductiontoR-Ccircuitsandcapacitortimeconstantsasstudiedinthecourse.

Part1oftheoriginallabasksthestudenttoobservedifferentsignalsgeneratedbyasignalgeneratorontheoscilloscope.ThissectionhasbeenomittedfromtheLabVIEWsimulationsbecauseallsimulationsdisplaytheinputwaveform.

Part2asksthestudenttobuildthecircuitshowninFigure2.Thelabasksthestudenttoobservetheoutputwhena40kHzsinewavewithamplitude10Vpeak-peakisappliedtothesystem.Thestudentisaskedaboutthephaseoftheoutputvoltageandcurrent.

Figure2

Part3oftheoriginallabasksthestudenttoinvestigatetheRCtimeconstantofthecircuitshowninFigure2,exchangingthe330pFcapacitorwitha0.01Fcapacitor.

Part4oftheoriginallabasksthestudenttoinvestigatethefrequencyresponseofthecircuit.Thestudentistoplottheobservedmagnitude,andcompareitwiththeexpectedmagnituderesponse.

2.7Lab1DesignDetails

Thecircuitpresentedinlab1isasingle-pole,analoglow-passfilter.AsgivenintheECE210classnotes[1],thetransferresponsesofthefilterinthetimeandfrequencydomainsaregivenas:

（1.1）

（1.2）

From

（2）,wecanderivethephaseresponsetobe:

（1.3）

Part2oflab1wasimplementedinLabVIEWbytakingadvantageof（1.2）and（1.3）.ALabVIEWVIdisplaysonecycleofasinewave,andappropriatelyscalesthetimeaxistoindicatethechosenfrequency.LabVIEWthencalculatesthephasedifferenceandmagnitudedifferenceduetoasinewaveofthegivenfrequency.ThenewmagnitudeandphasearethenusedasinputvaluesintoanewLabVIEWsignalgeneratorthatdisplaysamagnitudeandphaseshiftedsinewave,correspondingtotheidealoutput.Parts3and4oflab1useequation（1.1）toconvolvetheinputsignal,producingatimedomainoutput.

2.8Lab1DesignVerification

DesignVerificationwasaccomplishedbysimulatingthecircuitsinlab1inPSpiceandcomparingthePSpicesimulationswithourcalculatedvaluesandsimulationsinLabVIEW.Asspecifiedinthelabnotes,thestudentwillobservethephaseandmagnituderesponseofa40kHzsinewaveinput.Figure8showsthePSpicesimulation.OurMatlabsimulationbasedonequation（1.2）hadsimilarresults.Figure9showsthefrontpaneldisplayofourLabVIEWdesign,withresultsidenticaltoourMatlabsimulations.Asindicated,thestudentisabletoadjusttheinputfrequencyofthefrequencygenerator,aswellasresistanceandcapacitancevalues.ThissectionwasimplementedinLabVIEWbyoutputtingasinewavecorrespondinginthe“input”windowoftheVI.Next,thefrequencytransferfunction（1.2）wasusedtocalculatethemagnitudeandphaseresponseduetotheinputsinewave.Finally,magnitudeandphasedatawasusedtogenerateanewsinewaveattheinputfrequency,andoutputtedtothe“output”window.

ThenextpartofthelaboratoryinvestigatesR-Ctimeconstants.Ourcalculatedtimeconstantfrom（1.1）isRC=1x10-4seconds.OurPSpiceresults,showninFigure10,indicatethattheRCtimeconstantis10-4secondsaswecalculated.TheLabVIEWsimulationreflectstheidealcalculations,asshowninFigure11.Thisfrontpanelallowsthestudenttoadjustt