Research On Distributed Cooperation Jamming Methods Against Synthetic Aperture Radar

Using the advantages of all-time,all-weather,high gain and multi platform,SAR is widely used in many military fields,such as strategic intelligence collection,battlefield situation awareness,fire guidance and strike effect evaluation.In the past three decades of development,although SAR jamming technology has a considerable scale,the strong military demand has developed new SAR systems with the capabilities of high resolution,moving target indication and jamming suppression,which seriously limits the exertion of the existing SAR jamming efficiency.Based on this,in order to improve the confrontation ability of SAR imaging reconnaissance for high-value military targets and military important areas,and taking distributed cooperative jamming technology as a breakthrough,this paper has carried out in-depth research on three aspects: SAR jamming methods based on noise template modulation,multi-jammers countermeasures against SAR-GMTI based on signal domain cooperation and multi-jammers countermeasures against array SAR anti-jamming based on strategy-signal cooperation.The main reseach contents of this paper are as below:(1)The theoretical basis of SAR jamming.The classic working modes and imaging principle of SAR are briefly described.On this basis,SAR jamming are analyzed and demonstrated from four aspects of jamming feasibility,jamming scenario,jamming power and jammer working mechanism;And the simulation results of typical SAR jamming patterns are given,and their respective defects are pointed out,which paves the way for the development of this subject.(2)Research on SAR jamming methods based on noise template modulation.Enlightened by the idea of offline template modulation of deceptive jamming,this paper studies the jamming methods based on noise template modulation.Firstly,based on the traditional noise convolution modulation jamming,the slow-time jamming model is re-established,and then an improved jamming method is proposed.Through the offline slow-time filtering of the noise template,the azimuth suppression scope is effectively controlled and the utilization of jamming energy is improved.However,convolutional modulation jamming will always lag behind the jammer,which needs to be supplemented by additional frequency shift modulation,which will directly increase the complexity of jamming modulation and reduce the jamming response time.To solve this problem,using the bilateral spectral characteristics of the noise template,a smart jamming method of noise product modulation is further proposed.On the basis of keeping the one-step product of the intercepted signal in the time domain unchanged,the suppression area centered on the jammer can be effectively generated and controlled only by two-dimensional filtering of the noise template in fast and slow time domain offline;And if the noise template is further sampled in frequency domain,it can flexibly produce diversified jamming effects such as false point targets or dense point targets.Finally,based on a certain type of jammer of a certain unit,the semi-hardware simulation experiments of the two SAR jamming methods based on noise template modulation are carried out.(3)Research on cooperative jamming methods of multiple jammers against SAR-GMTI based on signal domain.Firstly,a unified jamming model based on noise jamming,convolution/product modulation and composite modulation is established,and the output results of three antenna SAR-GMTI cancellation and relocation of single jammer are deduced.It is pointed out that there are problems of blind jamming area and uncontrollable initial position of false targets.On this basis,using the smart jamming based on noise product modulation in Chapter three,a multi-jammers space-frequency cooperative modulation jamming method is proposed.Through frequency-domain cooperative modulation and spatial cooperative deployment,the jamming cancellation result is no longer affected by sinusoidal function modulation.It can not only effectively eliminate the blind jamming area,but also flexibly produce a variety of jamming effects such as coherent suppression and false point target deception.Still based on the noise product modulation jamming,a multi-jammer amplitude-frequency cooperative modulation jamming method is proposed.Through the cooperative modulation of frequency domain and amplitude,the additional phase of the synthetic jamming signal is eliminated,which can effectively reduce the jamming modulation time while controlling the false target GMTI relocation result.The effectiveness and performance of the two kinds of cooperative jamming against SAR-GMTI are verified and analyzed by simulation.(4)Research on multi-jammers countermeasures against array SAR anti-jamming methods based on strategy-signal cooperation.Aiming at the problem that multi-channel SAR along the track line can effectively eliminate noise jamming,a countermeasure method of multi-jammers is proposed,which is based on time sequence cooperation strategy.Taking dual channel SAR as the object,its cancellation effect on noise jamming is first analyzed and verified;On this basis,the time sequence cooperative jamming model of multiple jammers is established.By destroying the target echo after dual channel SAR cancellation,the imaging results appear azimuthal distortion or false targets with equal interval distribution;Or by destroying radar phase estimation of noise jamming,noise jamming is remained.The influence of jammer space deployment and different working time sequences on its anti cancellation performance is analyzed and verified in detail.Aiming at the problem that multi-channel SAR can suppress deception jamming,a counteraction method of multi-jammers based on amplitude coopreation modulation is proposed.Firstly,the deception jamming suppression effect of multi-channel SAR is analyzed and verified;On this basis,the deception model based on multi-jammers amplitude cooperation is established.By eliminating the additional phase of jamming signal caused by different propagation path,the jamming signal can obtain the same multi-channel coherent accumulation gain as target echoes,so as to counteract the deception jamming suppression of multi-channel SAR.The influence of the number of jammers and the number of SAR channels on its anti suppression performance is analyzed and verified in detail.