Study On Countermeasures Against Multi-Channel Synthetic Aperture Radar Ground Moving Target Indication

Multi-channel synthetic aperture radar ground moving target indication(SAR GMTI)methods are able to get the accurate information of ground moving targets,which can threaten the survival of military targets.Hence,the research on multi-channel SAR GMTI jamming technologies has become an important subject in an electronic countermeasure(ECM).There are three disadvantages in the traditional jamming technologies against the three-channel along track interferometry suppression method,including:1)the jamming effect based on a single jammer will be suppressed or cancelled in the detected result,2)barrage noise jamming cannot be generated in the whole detected processing,and 3)the verisimilar false ground moving targets cannot be generated.To overcome these disadvantages,jamming technologies against the three-channel along track interferometry suppression method are studied from three aspects,including jamming technologies based on a single jammer,a barrage noise jamming technology which can generate barrage noise jamming in the whole detected processing,and false moving targets and scenes deception jamming technologies.The major contents of this dissertation are addressed as follows:First,the reason why the jamming effect based on a single jammer will be suppressed in thedetected result is analyzed.The jamming effect based on a single jammer of the traditional deception jamming and the traditional barrage noise jamming have been classified into an enhanced jamming area and a weakened jamming area.In the weakened jamming area,the jamming effect will be suppressed or cancelled.By analyzing the jamming geometric model based on a single jammer,the reason why the jamming effect based on a single jammer will be suppressed is that the phase difference between different channels contains the azimuth positions of the jammer and jamming effect.An azimuth jamming filter is generated after the three-channel along track interferometry suppression processing,and the jammer is at the center of the filter.Jamming effect will be suppressed by the azimuth jamming filter according to the azimuth positions of the jammer and jamming effect.Second,a barrage noise jamming method is proposed based on double jammers against the three-channel along track interferometry suppression method.By controlling the azimuth distance between the jammers,the phase difference is destroyed,and thus the filter will not be generated,and then the whole detected processing will be covered by barrage noise jamming.The disadvantage that the jamming effect based on a single jammer will be suppressed or cancelled can be overcome by the proposed method.Compared with the traditional deception jamming methods based on multiple coherent jammers,the phase and amplitude difference of jamming signal do not need to be accurately controlled.In addition,the jamming energy of the proposed jamming is higher than that of barrage noise jamming based on a single jammer in the detected result.Third,a novel scattered wave deception jamming method with a narrow beam antenna is proposed against the three-channel along track interferometry suppression method.The radar signal is intercepted by a jammer which is set at an unmanned aerial vehicle.Then,by controlling the velocity of an unmanned aerial vehicle and the position of the jammer beam footprint,the intercepted radar signal is retransmitted to the assigned position.Jamming signal is generated and scattered by scatterered points on the ground,and a verisimilar false moving target will be generated in the detected result.With the three-channel along track interferometry suppression method,the position of the jammer beam footprint and the velocity of the unmanned aerial vehicle can be calculated by analyzing the difference of the range positions,the difference of the azimuth positions,the difference of the Doppler rate and the difference of the detected results between the ground moving target and the false moving target.Compared with the traditional deception jamming methods,the phase modulation and the time-delay modulation do not need to be performed,which reduces the algorithm complexity.Final,a false moving scene deception jamming method against the three-channel along track interferometry suppression method is proposed based on double jammers and the magnitude modulation.The identical false moving scenes will be generated in the assigned position by the two jammers utilizing the Doppler shift-frequency modulation and the time-delay modulation.To control the initial azimuth position of the false moving scene,the phase of each point,which is generated after superimposing two false scenes,is controlled by setting the magnitude ratio of the double scenes.Theoretical analysis shows that the false moving scene can be generated in the assigned position with the controllable initial azimuth position and magnitude by the proposed jamming method.Then,the jamming effect and influencing factors are analyzed.In addition,the application model of the proposed jamming method is established.Subsequently,the setting methods of the initial azimuth position and the magnitude compensation coefficient of the false moving scenes are presented.The requirement for the azimuth positions of two jammers in this proposed method is also determined.The multi-channel SAR GMTI jamming technologies studied in this dissertation can overcome the disadvantages of the traditional jamming technologies.The theoretical analysis and simulation experiments verify the effectiveness of the proposed methods.The results can be very important and useful guidelines for countering the multi-channel SAR GMTI.