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