Research On High-fidelity Active Deception Jamming Method Against SAR-GMTI

Synthetic aperture radar(SAR),as a kind of active imaging radar,has been widely applied in both battlefield reconnaissance and intelligence search fields,with advantages of such as all-day and all-weather.As a combination of SAR and ground moving target indication(GMTI),SAR-GMTI,can obtain the well-focused stationary targets image and moving targets information at the same time.With the rapid development and application of SAR-GMTI,the electronic countermeasure(ECM)to SAR-GMTI has attracted significant attention of the international radar community.As a hot spot of ECM research field,active deception jamming possesses the advantages of low jamming power,high flexibility and high fidelity.It aims at solving several key problems in the area of active deception jamming,and improving the fidelity of the deceptive target.The method and implementation of active deception jamming against SAR-GMTI is deeply studied in this dissertation,which provides certain technical reserves for the development and improvement of theory and applications in radar ECM.The main contents of this dissertation are listed as follows:1)Aiming at the problem of the motion representation of the false moving target in the convolution modulation process,an active deception jamming method against SAR-GMTI based on equivalent range model is proposed,which improves the fidelity of the motion characteristics in the time domain.The equivalent range model accurately represents the slant range information of uniform and uniform acceleration targets,thus ensuring the delay of the target motion characteristics and the accuracy of Doppler modulation.Based on the equivalent range model,the paper theoretically derives the two-dimensional frequency domain form of the target-related term in the frequency response function of the jammer system for the false targets with uniform velocity and uniform acceleration motion.The basic idea is to quickly generate the frequency response function of the jammer system by fast Fourier transform,Stolt interpolation and complex multiplication operation,which greatly reduces the computational complexity.The Stolt interpolation also realizes the distance-dependent azimuth modulation,range cell migration and range azimuth coupling of the false moving target,which further improves the fidelity of the false moving target.Finally,the simulation results show that this method not only produces false moving targets with high fidelity in motion characteristics simulation,but also has high efficiency.2)Aiming at the mismatch between the multi-channel SAR signal phase and radial velocity of the false moving target,an active deception jamming method against multi-channel SAR-GMTI based on multiple joint jammers is proposed,which improves the fidelity of the motion characteristics in the spatial domain..By utilizing multiple jammers,the cooperative deception jamming is performed at the signal level.It can fully exploit the advantages of the jamming signals of distributed jammers in spatial motion characteristics and generate the false targets with high-fidelity in multi-channel SAR-GMTI systems.In this paper,the multi-channel SAR signal model of false target is firstly analyzed,and the conditions for the generation of false targets with high-fidelity motion characteristics in spatial domain are analyzed.Then,the mathematical model of the cooperative deception jamming utilizing multi-jammers is proposed based on multi-channel additional phase cancellation.In order to achieve the purpose of matching the phase and radial velocity of the interference signal on all the channels,the proposed method requires that the number of jammers is consistent with the number of channels.At this time,the mathematical model has a unique analytical solution.Therefore,this paper proposes a fast algorithm for solving the analytical solution of multi-jammer cooperative modulation coefficients by means of Vandermonde determinant and Cramer's rule.Not only the algorithm has high calculation accuracy,but also avoids cumbersome matrix operations,which greatly reduced the amount of calculation.In addition,in order to further facilitate the application of the algorithm to engineering practice,this paper also proposes an optimal layout algorithm for multi-jammers based on the minimum condition number of the coefficient matrix.It is pointed out that by dividing a plurality of jammers equally spaced along the azimuth in the synthetic aperture range,and the interval is the synthetic aperture length divided by the number of channels,the condition number of the coefficient matrix reaches the minimum value.It is indicated that the linear system model is the most stable at this time,and the modulation weight of each jammer is least sensitive to the interference disturbance.Finally,the simulation results show that the proposed method significantly improves the fidelity of the false target signal in the spatial domain motion characteristics,and can achieve effective deception jamming for multi-channel SAR-GMTI.3)Aiming at the problem of scattering representation of false moving targets in different attitudes and frequency bands,an active deception jamming method against SAR-GMTI based on target electromagnetic model is proposed,which improves the fidelity of the scattering characteristics.This method is achieved by using optimized target electromagnetic model database,scattering feature extraction,two-dimensional interpolation and motion feature modulation.It leads to that the deceptive moving target has high fidelity in scattering features.Based on the monostatic bistatic equivalence principle,the equivalent bistatic scattering data is used to represent the scattering data under the traditional monostatic SAR observation,which greatly reduces the computational complexity.Moreover,after adopting the strategy of azimuth dimension segmentation in database modeling,the frequency scattering data required in the synthetic aperture range can be directly extracted by one search,which greatly simplifies the algorithm flow.Finally,the effectiveness of the proposed algorithm is verified by simulation experiments.