资源描述:
《电子信息类专业英语Unit14DigitalSignalProcessing.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、Unit14DigitalSignalProcessingTextKeywordsTechnicaltermsExpressionsNotestothetextTextWhatisDSP?DSP,orDigitalSignalProcessing,asthetermsuggests,istheprocessingofsignalsbydigitalmeans.Asignalinthiscontextcanmeananumberofdifferentthings.Historicallytheoriginsofsignalprocessingareinelectricalengi
2、neering,andasignalheremeansanelectricalsignalcarriedbyawireortelephoneline,orperhapsbyaradiowave.Moregenerally,however,asignalisastreamofinformationrepresentinganythingfromstockpricestodatafromaremote-sensingsatellite.Theterm“digital”comesfrom“digit”,meaninganumber,so“digital”literallymeansn
3、umerical.Adigitalsignalconsistsofastreamofnumbers,usually(butnotnecessarily)inbinaryform.Theprocessingofadigitalsignalisdonebyperformingnumericalcalculations.AnalogandDigitalSignalsInmanycases,thesignalofinterestisinitiallyintheformofananalogelectricalvoltageorcurrent,producedforexamplebyami
4、crophoneorsomeothertypeoftransducer.Insomesituations,suchastheoutputfromthereadoutsystemofaCD(compactdisc)player,thedataisalreadyindigitalform.AnanalogsignalmustbeconvertedintodigitalformbeforeDSPtechniquescanbeapplied.Ananalog-to-digitalconverterorADC.Thisgeneratesadigitaloutputasastreamofb
5、inarynumberswhosevaluesrepresenttheelectricalvoltageinputtothedeviceateachsamplinginstant.SignalProcessingSignalscommonlyneedtobeprocessedinavarietyofways.Forexample,theoutputsignalfromatransducermaywellbecontaminatedwithunwantedelectrical“noise”.Theelectrodesattachedtoapatient’schestwhenanE
6、CGistakenmeasuretinyelectricalvoltagechangesduetotheactivityoftheheartandothermuscles.Thesignalisoftenstronglyaffectedby “mainspickup”duetoelectricalinterferencefromthemainssupply.Processingthesignalusingafiltercircuitcanremoveoratleastreducetheunwantedpartofthesignal.Increasinglynowadays,th
7、efilteringofsignalstoimprovesignalqualityortoextractimportantinformationisdonebyDSPtechniquesratherthanbyanalogelectronics.ApplicationsofDSPDSPtechnologyisnowadayscommonplaceinsuchdevicesasmobilephones,multimediacomputers,videorecorders,CDplayers,h