Research On SAR Deception Jamming Based On Intermittent-Sampling Repeater Jamming

Synthetic aperture radar(SAR),a new technology of battlefield reconnaissance after optical detection,is playing an important role in the military field and making the research of radar electronic countermeasures step into a new era.With the consecutive breakthroughs in the field of SAR,the jamming against SAR also develop a lot..With the development of digital signal processing(DSP)technology and digital radio frequency memory(DRFM)technology,the research for deception jamming against SAR has become a hot issue.As a novel method of coherent deception jamming,intermittent sampling repeater jamming(ISRJ)does not only generate effective false targets against linear frequency modulated pulse compression(LFMPC)radar,but also has the advantage of receiving/transmitting time-sharing.The research of ISRJ against SAR is still in its infancy.This thesis studies the application of ISRJ against SAR deeply and systematically,and provides an improvement of current method.The results through MATLAB simulation shows the feasibility of the improvement.ISRJ against SAR can generate a series of false targets for deception jamming.However,due to the periodic characteristics of the jam signal,the location distribution between the false targets has concrete rules,and therefore the real targets are very obvious and easy to be detected.A new cancellation method is proposed with the consideration of the effective combination of deception jamming and suppressing jamming.This method takes the advantage of the theory of radar active cancellation,frequency shift and ISRJ.The signal after intermittent sampling needs a frequency shift during fast time domain to reach quasi synchronous.To get a cancellation signal,the amplitude should be the same with the raw signal while the phase should be reverse.With the analysis of the output of the matched filter,the parameters satisfying the cancellation condition are given,and the concept of the cancellation degree and the effective cancellation degree are come up.The simulation results show that the new method can not only effectively produce false targets,but also solve the problem of"asynchrony"and successfully get the cancellation of the main false target and the real target in short time delay.Under varies error of phase,amplitude and frequency,there are three curves of cancellation degree,which provides a guidance for the parameter selection in the engineering practice.An innovation method for cancellation is proposed to kill the error of frequency shift which mainly comes from estimation error on the LFM slope called.This method is based on N orders spectrum spread and compression(SSC).The multiplication of two signals,one of which is the N times of signal after intermittent sampling,the other one of which is the conjugate of N-1 times of signal after intermittent sampling and a delay,can get a frequency shift that has nothing to do withK_r,and the cancellation will be achieved by the output signal.The simulation results show that the effectiveness of the proposed method is much better than that of the direct shift frequency method when the sameK_r estimation error is applied.The new method has a good adaptability of theK_r error.The main contribution of this dissertation is the enrichments and developments in the applications of intermittent sampling and forwarding in SAR jamming.This research provides an new ideology for the future research and has certain theoretical guiding significance.