ADS的培训资料23commsysrev5Lab10.docx
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ADS的培训资料23commsysrev5Lab10.docx
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ADS的培训资料23commsysrev5Lab10
23
23Lab10:
AgilentPtolemy:
MeasuringtheBER
23Lab10:
AgilentPtolemy:
MeasuringtheBER23-1
23.1Objectives:
23-5
23.2SchematicCaptureandSimulationSetup:
23-5
23.2.1TheReferenceSymbols:
23-5
23.2.2TheSignalwithoutNoise:
23-5
23.2.3TheBERMeasurementElement:
23-6
23.2.4BERSimulationResults:
23-8
23.3SweptEs/NoBERMeasurements:
23-9
23.3.1SweepingtheEs/No:
23-9
23.3.2SweptES/NoBERMeasurementResults:
23-10
23.4BERMeasurementDetails:
23-10
23.5ReviewofLab10:
23-11
23.1Objectives:
∙InspecttheBERsetupofthetoplevelPI4DQPSKsystemdesign.
∙ExamineandvalidatetheBERperformanceofthetop-leveldesign.
23.2SchematicCaptureandSimulationSetup:
23.2.1TheReferenceSymbols:
1.Opentheprojectd:
\users\ads\CommSys_Lab10_prj.
2.Opentheschematic“a_Final_PI4DQPSK_Sys”.Thisisthesimilartotheschematicthatwasbuiltinthepreviouslab.IthasbeenmodifiedtosimulatefasterbysubstitutingaP2D(PowerDependentS-parameterfile)inplaceoftheRFICamplifierinthetransmittersubcircuit.
3.“SaveAs…”thedesignwiththenewname“b_IIS_BER”.
23.2.2TheReceiverInputSignal:
4.
Inserta“SplitterRF”,fromthe“TimedLinear”library,betweenthe“AntBase”andthe“Receiver”,asshownhere.
Thissplittercreatesanewpathtoenablemonitoringthesignalreceivedbythebasestationantennaandpresentattheinputofthebasestationreceiver.
Thissignalhasnoreceivernoisesuperimposedtoit.TheentirenoisecontributionwillbemodeledbytheBERsinkelement.
5.Adda“GainRF”componentfromthe“TimedNonlinear”library.Settheparameter:
∙Gainto1000
∙GCTypetoNone
Thisamplifieradjuststheverylowreceivedsignallevel,to1V.Thegainissignificantlyhigh,asthesignalreceivedisverysmall.Theamplifierhastobeanideallinearamplifier.ThisiswhyitisimportanttosettheGCType(GainCompressionType)to“None”;thisgivesalinearamplifiermodel.
6.
Adda50termination(fromthe“TimedLinear”library)anda“TimedSink”(fromthe“Sinks”library)attheoutputofthisamplifier,asshownhere.Setthenameofthetimedsink:
∙InstanceNametoRcvr_Input
Thissinkwillmonitorsignalwithnoreceivernoise(tocheckitslevel,forexample).
23.2.3TheBERMeasurementElement:
7.Adda“berIS”componentfromthe“Sinks”library.ThisistheelementperformingtheImprovedImportanceSamplingBERmeasurement.Allothercomponentsaddedsofarareprovidingthenecessaryinputstothismeasurement.Settheparameters:
∙InstanceNametoPE_Actual
∙StarttoDFstartuSec
∙SymbolTimetoSym_time
∙NBwto1/Sym_time
∙SystemtoQPSK
∙EsOverNoto6.0
8.Connectthe“berIS”asshownhere:
-“Sig”inputto“Rcvr_Input”timedsink
-“Test”inputtoNamedNode“Test”from“I”outputonDemod
-“Ref”inputtoNamedNode“Ref”from“Iref”sink
23.2.4BERSimulationResults:
9.Thesimulationshouldtakeabout3minutes.
10.
OpenanewdatadisplayanddisplaythePE_Actualina“List”,asshownhere:
Theresultshowsaprobabilityoferrorof4.2*10-2fortheEsoverNoratioof6dB.
11.
Display“Iout”,“Iref”andtherealpartof“Rcvr_Input”,usingtheeye()function,asshownhere:
Theparameters,Iout,Iref,Rcvr_Inputcanalsobeediteddirectlyonthegraph.
Theseplotscanbeusedtocheckthelevelsofthesignalsandhowwelldotheoutputsymbolscorrespondtothereferencesymbols.
12.Savethedatadisplaywiththename“b_IIS_BER”.
23.3SweptEs/NoBERMeasurements:
23.3.1SweepingtheEs/No:
Withthisaddition,theareaoftheschematiccontainingthe“berIS”sinkshouldlookasshownhere.
1.AddaVar/EqnblockandcreatethevariableEsNo=6.0.
2.IntheberISelementchangethevalueEsOverNotothevariableEsNo.
3.AddaparametersweepcomponentfromtheControllerspalette.Makethefollowingchanges.
∙AssignSweepVarastheparameter“EsNo”.
∙AssignSimInstanceName[1]thenameofthesimulationcontroller“DF1”.
∙AssigntheStart,StopandStepvalues:
∙Start=2
∙Stop=12
∙Step=2
4.Savetheschematicasb_IIS_BER_swp.
23.3.2SweptES/NoBERMeasurementResults:
13.Thesimulationtakesabout15minutes.Tosavetime,theresultshavebeensavedinthedatasetnamed“b_IIS_BER_swp”.Eithersimulatethissystemoropenthedatadisplay“b_IIS_BER_swp”.
14.Display“PE_Actual[:
:
0]”inatabulardisplay.
15.Adda“RectangularPlot”anddisplaythe“PE_Actual[:
:
0]”ChangethescaleoftheY-axistologarithmic(under“PlotOptions”tabinthe“PlotTracesandAttributes”window).ThiswilldisplaytheBERvs.Es/Nocurve.
16.
Savethedatadisplaywiththenewname“b_IIS_BER_swp”.
Thedatadisplaywindowshouldlooksimilartotheresultsshownhere.
ObservetheprobabilityoferrorperformanceofthefinalsystematvariousEs/No.A0.1%BERoccursatapproximately10.5dB,whichexceedsthespecificationby3.5dB.
23.4BERMeasurementDetails:
Therearethreeinputs.Thebottominputisfortheidealrectangularsymbolsbeforefiltering.Thesewillbeusedasthereferenceincomparingthedemodulated(test)symbols.
Themiddleinputisforthetestsymbols.Thesearethedemodulatedsymbolsattheoutputofthedemodulator.
Thetopinputisforasampleofthesignalwithoutnoise.ItshouldbeconnectedtothepointinthesystemtowhichtheEs/Noistobereferencedto.TheEs/Noistobereferencedtothereceiverinputinthisexample,soasplitterisaddedtosamplethesignalatthispoint.Anidealamplifierisusedtonormalizethesymbolamplitudeto+/-1V.NotethatallinputstotheberISarescaledto+/-1V.Idealgainblockscanbeusedtoaccomplishthisiftheseinputsarenotalready+/-1V.
ThemeasurementessentiallyaddsnoisetothetestsignalatthemeasurementandusestheNBWtocalculatetheEs/Noatthereceiverinput.ThustheNBWshouldalwaysreflectthenoisebandwidthofwhateverisbetweentheSigandTestinputoftheberISmeasurement.Thiswouldtypicallybe1/(2*SymTime)forabasebandsystemand1/SymTimeforaRFsystem,iftheyareNyquistfiltered.SincetheberISsinkisessentiallyinjectingnoiseatthesinkinput,allothernoisesourcesfromthedesignshouldbeturnedoffforaccuratemeasurementofEs/No.
AVARblockisusedtodefineEs/NofortheberISmeasurement.ThiscanthenbeswepttogeneratetheBERcurve.
NotethattheDFstopdidn'tneedtobechangedforthissimulation.TheberISmeasurementautomaticallycontrolsthesimulationlengthtotestthecorrectnumberofsymbolsforavalidmeasurement.TheEstVarcontrolsthelengthofthesimulationandconfidenceinthemeasurementresults.Inthisexample,theEstVarissetto0.1,whichwouldsetthesimulationlengthsothatitcountsapproximately10(or1/0.1)symbolerrors.AnEstVarof0.01wouldsetthesimulationlengthsothatitcountsapproximately100(or1/0.01)symbolerrorsforamoreaccurateresult(usingalongersimulation).
TheberISmeasurementinthisexampleisonlymeasuringtheIsymbolerrorrate.AnotherberISmeasurementcouldbeplacedtomeasuretheQsymbolerrorrateandtheactualtotalsymbolerrorratecouldbecalculatedfromthetwomeasurementsasfollows:
Pser=Pei+Peq-Pei*Peq
WherePseristhetotalprobabilityofanerroroccurringonanIorQsymbol.
23.5ReviewofLab10:
Inthislab,theBERperformanceofthefinaltop-levelsystemwasobserved.TheberISsinkwasusedtomeasurethesymbolerrorrate.
SweptEs/NomeasurementswereperformedtodeterminetheBERcurveofthesystem.Theperformanceofthesystemwascheckedagainstthedesignspecification.
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