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简介：Forreal-timejammingsignalgenerationindeceivinginversesyntheticapertureradar(ISAR),thetargetcharacteristicsmodulationisalwaysprocessedintheexpensivefieldprogrammablegatearray(FPGA).Duetothelargecomputationalcomplexityofthetraditionalmodulatingoperation,thesizeandstructureofsimulatedfalse-targetarelimited.Withregardtotheprincipleofdechirpinginrangecompressionoflinearfrequencymodulated(LFM)radar,anovelalgorithmnamed'inversedechirping'isproposedfortargetcharacteristicsmodulation.ThisalgorithmonlyneedsonecomplexmultiplierintheFPGAtogeneratethejammingsignalwhentheradarsignalisintercepted,whichcanbeobtainedbymultiplicationofradarsignalsamplingsandtheequivalentdechirpedtargetechointhetimedomain.Asthecomplexsynthesisofdechirpedtargetechocanberealizedbycheapdigitalsignalprocessor(DSP)withintheinterpulsetime,theoverallcostofthejammingequipmentwillbereducedandthefalse-targetsizewillnotbelimitedbythescaleofFPGA.Numericalsimulationsareperformedtoverifythecorrectnessandeffectivenessoftheproposedalgorithm.

简介：ThispaperinvestigatesthedesignofdigitalSigma-DeltaModulator(SDM)forfractional-Nfrequencysynthesizer.CharacteristicsofSDMsarecomparedthroughtheoryanalysisandsimulation.Thecurveofmaximum-loop-bandwidthvs.maximum-phase-noiseissuggestedtobeanewcriteriontotheperformanceofSDM,whichgreatlyhelpsdesignerstoselectanappropriateSDMstructuretomeettheirrealapplicationrequirementsandtoreducethecostaslowaspossible.Alow-spur3-orderMul-tistageNoiseShaping(MASH)-1-1-1SDMusingthree2-bitfirst-ordercascadedmodulatorsisproposed,whichbalancestherequirementsoftone-freeandmaximumoperationfrequency.

简介：BasedontheanalysisofthespuriousintroducedbyphaseaccumulationtruncationwhichwasmadebyNicholas,anewsimplifiedalgorithmforspuriousspectruminthepresenceofphasetruncationispresentedbyusingthemappingmathematicsandnumbertheoreticmethod,itispossibletopreciselyanalyzethespuriouslocationandthespuriousamplitudeintroducedbyphasetruncationinpracticalapplicationsbycomputer.

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