Research On Sidelobe Suppression Algorithm Of Frequency-agile Coherent Radar

Frequency-agile coherent radar(FACR)has become one of the hot-spots in radar field because of its advantages such as low interception,anti-jamming and good electromagnetic compatibility.Different carrier frequencies of frequency-agile coherent radar make it impossible to use the traditional method of coherent processing.Aiming at the problem of high side-lobe in frequency-agile radar,the velocity dimension,range dimension side lobe suppression and sparse reconstruction side-lobe suppression are studied in this paper.The main tasks are as follows:(1)We study the echo signal model of frequency agile radar,the ambiguity function of random frequency agile coherence,and analyze the influencing factors of ambiguity function on the side-lobe of velocity dimension and distance dimension..We fix agile bandwidth,then,study the fuzzy function speed-distance dimension performance of different random agile points.Experiments show that the side lobes of velocity dimension are related to the augmentation point order,while the side lobes of distance dimension are basically not affected by the agile point,which is related to the nature of the base band signal itself.This study provides the basis for the subsequent processing of the agile.(2)This paper studies the target side-lobe suppression method based on phase compensation for integer double-speed variable-phase coherent radar.The phase compensation model is established,the velocity dimension side lobe suppression and the distance dimension side-lobe suppression algorithm are studied,respectively.In the case of many frequency points,it is proposed to optimize the transmission frequency based on simulated annealing and improved genetic algorithm,and optimize the frequency side suppression of speed dimension.The simulation results show that the proposed method can reduce the integrated side lobes by about 7d B and the peak side lobes by about 2d B.When the frequency is small,the discrete continuous model is introduced to reduce the repetition probability of adjacent transmitting frequencies.Simulation verification,this method can reduce the integral side-lobe suppression by about 2d B.The auto-correlation function of the two-phase coding and multi-phase coding of the agitated radar base band signal is studied,and the distance-dimensional integrated side-lobe minimization model is established.The simulated annealing algorithm is used to optimize the phase encoding.The simulation experiments verify that the sidelobe of 64-bit two-phase code has an average suppression of 6d B,and the sidelobe of 80-bit polyphase code has an average suppression of 7d B.(3)A method of adjacency coherent radar side-lobe suppression based on sparse reconstruction is proposed.The sparse model of Agile Coherent Radar is established.The-norm,Compressive Sampling Matching Pursuit(Co Sa MP)and Sparse Bayesian Learning(SBL)algorithms are studied under different conditions.The target is sparsely reconstructed.The velocity-distance dimension 1lsidelobe suppression performance of sparse reconstruction targets is analyzed.Experiments show that the sparse Bayesian learning algorithm reconstructs the best side-lobe suppression results.