Anti-Jamming Technology Of Cognitive Radar Based On Adaptive Agile Waveform

Cognitive Radar is a new Radar system,which has the ability of learning,understanding,and deducing the environment,also has the ability of a continuous feedback between the transmitter and receiver and the ability of adaptive waveform transmit.The jamming technology is changing and developing,and affects the radar’s performance seriously,so the anti-jamming is very important.Due to the limited improvement of anti-jamming in traditional radar,we can choose adaptive agile waveform in cognitive radar to anti jamming.Firstly,this paper has studied the knowledge aid of cognitive radar,and has analyzed the characteristics of suppressing jamming and deception jamming;then this paper proposes an anti-jamming technology of cognitive radar based on adaptive agile waveform;finally,the simulation shows that adaptive agile waveform can effectively improve SINR in receiver.The main work of this paper is as follows:(1)We analyze the module of jamming.We compare the model of suppressing jamming and deception jamming in cognitive radar.We analyze the characteristic of suppressing jamming in time and frequency domain.In the view of suppressing jamming,the time and frequency domain forms and their characteristics of different modulation jamming models are analyzed.We analyzed the infrastructure based on digital radio frequency memory(DRFM),the copy mode of intermittent sampling and all-pulse sampling,and the jamming mode of false target jamming and pull-off jamming.(2)In the view of suppressing jamming,we propose the waveform design for equally suppressing jamming and side lobes in cognitive radar based on moving target detection.Firstly,we design optimal model in the constraint of equality of side lobes level and jamming level in receiver according to the minimum mean square error(MMSE)principle.Lagrange multiplier method and alternate iteration method are used to solve the model to suppress interference and side-lobe equally.Then improve the algorithm to improve the jamming suppression dynamic range.Finally,the feasibility of the algorithm is verified by simulation.Then we decompose it to objective function which is multivariate and multi-constraint by alternating direction method.Then we solve the function by introducing multiple auxiliary variables and the KKT optimal conditional in Lagrange-multiplier method.Finally,we evaluate the performance of this algorithm.(3)In the view of suppressing jamming,we propose a cognitive radar two-dimensional anti-jamming waveform design.Firstly,we study two-dimensional modulation optimization criteria and mathematical model for anti-jamming at the transmitter from ambiguity function.Secondly,we design the dimension reduction strategy to disassemble complex high-dimensional optimization problems into multiple low-dimensional sub-optimization problems.Then,the Lagrange multiplier method and the alternating iterative method are used to solve the model to suppress the jamming and side lobes.Finally,we evaluate the performance of this algorithm.(4)In the view of deception jamming,we consider cognitive radar anti-deception jamming orthogonal LFM-PC agility waveform design method.Firstly,we study fully agile quadrature LFM-PC waveform design model and minimizes deception jamming and target signal side lobes in the range-Doppler range.Secondly,we design the dimension reduction strategy to disassemble complex high-dimensional optimization problems into multiple low-dimensional sub-optimization problems.The conjugate gradient method is used to solve the model.Finally,we evaluate the performance of this algorithm.