英文缩写--数字电视发射机

1AbbreviationsACEActiveConstellationExtensionADSLAsymmetricdigitalsubscriber(订户)line--ACOFDM-codeddigitaldatastreamwitharateupto8Mbit/s(downstream)and1Mbit/s(upstream)istransmittedviatelephonelines,mainlyforvideoondemand.QAMQuadratureAmplitudeModulationTypeofmodulationfordigitalsignals(DVB-Cand-T).TwosignalcomponentsIandQareeachquantizedandmodulatedontotwoorthogonalcarriersasappropriatefortheQAMlevel(4,16,32,64,128,256).TheconstellationdiagramisobtainedbyplottingthesignalcomponentswithIandQasthecoordinateaxes.Therefore,2,4,5,6,7or8bitsofadatastreamaretransmittedwithonesymbol,dependingontheQAMlevel(4,16,32,64,128,256).ThistypeofmodulationisusedincablesystemsandforcodingtheCOFDMsinglecarriersATSCAdvancedTelevisionSystemsCommittee--americanstandardizationgroupfordigitalterrestrialtransmission16-QAM16-aryQuadratureAmplitudeModulation256-QAM256-aryQuadratureAmplitudeModulation264-QAM64-aryQuadratureAmplitudeModulationACMAdaptiveCodingandModulationBBBaseBandBCHBose-Chaudhuri-HocquenghemmultipleerrorcorrectionbinaryblockcodeBICMBitInterleavedCodingandModulationCBRConstantBitRateCNRCarriertoNoiseRatio--IndicateshowfarthenoiselevelisdownoncarrierlevelCCMConstantCodingandModulationCICellInterleaverCRCCyclicRedundancyCheckCOFDM(DVB-T)CodedOrthogonalFrequencyDomainMultiplex--Upto6817singlecarriers1.116kHzapartareQAMmodulatedwithupto64states.Codedmeansthatthedatatobemodulatedhaserrorcontrol.Orthogonalitymeansthatthespectraoftheindividualcarriersdo(almost)notinfluenceeachotherasaspectralmaximumalwayscoincideswithaspectrumzerooftheadjacentcarriers.Asingle-frequencynetworkisusedfortheactualtransmission.ConstellationDiagram--WayofrepresentingtheIandQcomponentsforQAMorQPSKmodulation.ThepositionofthepointsintheconstellationdiagramprovidesinformationaboutdistortionsintheQAM3orQPSKmodulatoraswellasaboutdistortionsafterthetransmissionofdigitallycodedsignals.DDecimalnotationDBPSKDifferentialBinaryPhaseShiftKeyingDFLDataFieldLengthDNPDeletedNullPacketsDVBDigitalVideoBroadcasting--BroadcastingTVsignalstoadigitalstandardDVB-CDigitalVideoBroadcasting-CableBroadcastingTVsignalstoadigitalstandardbycableDVB-SDigitalVideoBroadcasting-SatelliteBroadcastingTVsignalstodigitalstandardviasatelliteDVB-TDVBsystemforTerrestrialbroadcastingTerrestrialbroadcastingofTVsignalstodigitalstandardDVB-T2DVB-T2SystemasspecifiedinthepresentdocumentConvolutionalCodingThedatastreamtobetransmittedviasatelliteandterrestrial(DVB-S,DVB-T)isloadedbitbybitintoshiftregisters.Thedatawhichissplitanddelayedasitisshiftedthroughdifferentregistersiscombinedinseveralpaths.Thismeansthat4doublethedatarate(2paths)isusuallyobtained.Puncturingfollowstoreducethedatarate:thetimesequenceofthebitsispredefinedbythiscodingandisrepresentedbythetrellisdiagram.EBUEuropeanBroadcastingUnionEITEventInformationTable--TVguideETTExtendedTextTable--TableID0XccETMExtendedTextMessageFECForwardErrorCorrectionErrorcontrolbitsaddedtousefuldataintheQAM/QPSKmodulatorforDVB-C,-SandDVB-T.FEFFutureExtensionFrameFFTFastFourierTransformFIFOFirstInFirstOutGCSGenericContinuousStreamGFGaloisFieldGFPSGenericFixed-lengthPacketizedStreamGSGenericStreamGSEGenericStreamEncapsulationHEMHighEfficiencyModeHEXHexadecimalnotationIFIntermediateFrequencyIFFTInverseFastFourierTransformISInteractiveServicesISCRInputStreamTimeReferenceISIInputStreamIdentifier5ISSYInputStreamSYnchronizerISSYIInputStreamSYnchronizerIndicatorLDPCLowDensityParityCheck(codes)LSBLeastSignificantBitMISMultipleInputStreamMISOMultipleInput,SingleOutputNOTE:Meaningmultipletransmittingantennasbutonereceivingantenna.MODCODMODulationandCODingMPEGMotionPictureExpertsGroup--sometimescalledMovingPictureExpertsGroupMUSICAMMaskingPatternAdaptedUniversalSub-bandIntegratedCodingandMultiplexingCompressionmethodforaudiocodingMSBMostSignificantBitMSSModulationSignallingSequencesNANotApplicableNMNormalModeNPDNull-PacketDeletionO-UPLOriginalUserPacketLengthPAPRPeaktoAveragePowerRatioPCRProgrammeClockReference节目时钟基准--ReferenceinTSforthe27-MHzclockrecovery.Transmittedatleastevery0.1secPCMPulseCodeModulation6PER(MPEGTS)PacketErrorRatePIDPacketIdentification--IdentificationofprogramsinthetransportstreamPLLPhaseLockedLoopPLPPhysicalLayerPipePRBSPseudoRandomBinarySequencePayLoadUsefuldatainTSPredictionPredictionofapicture(PorB)withindicationofamotionvectorProfileSubdivision(细分，一部)ofvideocodingintodifferentresolutionsPSProgramStream--MultiplexofseveralaudioandvideoPESusingthesameclock.QQuantizationQ-1InversequantizationQSQuantizationscalingQEFQuasiErrorFree--LessthanoneuncorrectederrorperhourattheinputoftheMPEG2decoder.(BER10-11)QPSKQuaternaryPhaseShiftKeyingTypeofmodulationfordigitalsignals(DVB-Sand-T).Thedigital,serialsignalcomponentsIandQdirectlycontrolphaseshiftkeying.TheconstellationdiagramwithitsfourdiscretestatesisobtainedbyrepresentingthesignalcomponentsusingtheIandQsignalsascoordinateaxes.Duetothehighnonlineardistortioninthesatellitechannel,thistypeofmodulationisusedforsatellitetransmission:7The4discretestatesallhavethesameamplitudethatiswhynonlinearamplituded