毕业论文外文翻译-对载波跟踪混合DS 跳频扩频测控系统的研究

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1、AbstractResearchonCarrierTrackinginHybridDS/FHSpreadSpectrumTT&CSystemAbstractBecauseoftheeffectofcarrierfrequencyhopping,theinputIFsignalofcarriertrackingloopinDS/FHSS(DirectSequence/FrequencyHoppingSpreadSpectrum)TT&C(Telemetry,Tracking&Command)Systemischaracterizedbyth

2、eDopplerfrequencyagile.Thetrackingloopwillshifttothefrequencystepresponsestateceaselesslyandthemeasurementresolutionseverelydecline,eventheloopislikelytobeunlocked.Thispaperpresentsacarriertrackingloopaidedbyfrequencyhoppingpattern.Inordertokeepthestabilityofthetrackinglo

3、op,theDopplerfrequencyagilityinthenextfrequencyhoppingdwellisestimatedandtimelycompensatedtothefrequencyadjustmentofcarrierNCOaccordingtothepresetfrequencyhoppingpatternandcurrentspacecraftvelocity.Simulationresultsshowthatthismethodeffectivelyeliminatestheinstabilityduet

4、ocarrierfrequencyhopping,andtheresolutionofloopmeetstherequirementofTT&Csystem.Keywords：carriertracking；DS/FHSS；frequencyagility；aided；TT&CIResearchonCarrierTrackinginHybridDS/FHSpreadSpectrumTT&CSystemI．INTRODUCTIONThemainfunctionofTT&C(Telemetry,TrackingandCommand)syste

5、misrangingandvelocitymeasurement.Presently,themostcommonusedTT&Csystemsareunitcarriersystemandunitspreadspectrumsystem.FortheunitcarrierTT&Csystem,rangingisrealizedbymeasuringthephasedifferencebetweentransmittedandreceivedtones,andfortheunitspreadspectrumTT&Csystem,accord

6、ingtotheautocorrelationpropertiesofPNcode,rangingisrealizedbymeasuringthephasedelaybetweenthereceivedandlocalpseudonoise(PN)code.VelocitymeasurementinbothofTT&CsystemsdependsonextractingthefrequencydifferenceresultingfromtheDopplerphenomenabetweenthetransmittedandreceived

7、carrier.Whilealltheprocessesmentionedabovearefinishedonthegroundofhighresolutioncarriertracking,andthephaselockloopisthecommonusedmethodtoimplementitinTT&Csystem.Asthespaceelectromagnetismenvironmentbecomemoreandmorecomplicated,thecapabilityofanti-jammingisrequiredbythefu

8、tureTT&Csystem[1].SoweconsiderusingthehybridDS/FHSS(DirectSequence/FrequencyHoppingSpreadSpectru