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1、DIGITALSIGNALPROCESSINGTERMINOLOGY1/fnoise:Atypeofrandomnoisethatincreasesinamplitudeatlowerfrequencies.Itiswidelyobservableinphysicalsystems,butnotwellunderstood.Seewhitenoiseforcomparison.-3dBcutofffrequency:Thedivisionbetweenafilter'spassbandandtransitionband.Definedasthefrequencywh

2、erethefrequencyresponseisreducedto-3dB(0.707inamplitude)."A"law:CompandingstandardusedinEurope.Allowsdigitalvoicesignalstoberepresentedwithonly8bitsinsteadof12bitsbymakingthequantizationlevelsunequal.Seemulawforcomparison.AC:AlternatingCurrent.Electricaltermfortheportionofasignalthatfl

3、uctuatesaroundtheaverage(DC)value.Accuracy:Theerrorinameasurement(oraprediction)thatisrepeatablefromtrialtotrial.Accuracyislimitedbysystematic(repeatable)errors.Seeprecisionforcomparison.Additivity:Amathematicalpropertythatisnecessaryforlinearsystems.Ifinputaproducesoutputp,andifinputb

4、producesoutputq,thenaninputofa+bproducesanoutputofp+q.Aliasing:Theprocesswhereasinusoidchangesfromonefrequencytoanotherasaresultofsamplingorothernonlinearaction.Usuallyresultsinalossofthesignal'sinformation.Amplitudemodulation:Methodusedinradiocommunicationforcombininganinformationcarr

5、yingsignal(suchasaudio)withacarrierwave.Usuallycarriedoutbymultiplyingthetwosignals.Analysis:TheforwardFouriertransform;calculatingthefrequencydomainfromthetimedomain.Seesynthesisforcomparison.Antialiasfilter:Low-passanalogfilterplacedbeforeananalog-to-digitalconverter.Removesfrequenci

6、esaboveone-halfthesamplingratethatwouldaliasduringconversion.ASCII:Amethodofrepresentinglettersandnumbersinbinaryform.Eachcharacterisassignedanumberbetween0and127.Verywidelyusedincomputersandcommunication.Aspectratio:Theratioofanimage'swidthtoitsheight.Standardtelevisionhasanaspectrati

7、oof4:3,whilemotionpictureshaveanaspectratioof16:9.Assembly:Low-levelprogramminglanguagethatdirectlymanipulatestheregistersandinternalhardwareofamicroprocessor.Seehigh-levellanguageforcomparison.Associativepropertyofconvolution:Writtenas:.Thisis(a[n]tb[n])tc[n]’a[n]t(b[n]tc[n])importa