Research On The Method And Realization Of Interference Suppression At Sub-Array Level Based On Phased Array Radar

When the phased array radar carries out target searching and target tracking,if the interference falls within the main lobe of the antenna pattern,the existence of the jamming signal will greatly reduce the searching and tracking effect of the phased array radar.resulting in serious consequences such as the decrease of direction finding accuracy and even the loss of targets.Many existing main lobe interference suppression algorithms have high computational complexity,which are difficult to meet the real-time requirements of engineering,and can not take into account the suppression of sidelobe interference under the condition of strong main lobe interference.Large phased array radar often has tens of thousands of array elements.In order to reduce the computational complexity of the algorithm,it is necessary to reduce the dimension of the array by dividing subarrays.In order to solve the above problems,an improved sub-array interference suppression method based on phased array radar signal processing system is proposed in this paper.The specific research contents are as follows:Firstly,this paper introduces the basic theory of subarray beamforming.The narrowband array signal model of phased array radar is constructed,and on the foundation,the subarray division mode and the basic theory of subarray level beamforming are introduced.Then,three commonly used optimal filtering criteria of weight vectors are derived in detail,and the basic principle of adaptive beamforming at subarray level is researched.Finally,the special-shaped array used in a project is taken as the array face.The interference countermeasure effect of adaptive beamforming at subarray level and the processing effect of adaptive beamforming in the presence of main lobe interference are studied by simulation.In view of the situation that the echo signal contains main lobe interference,this paper first discusses three classical sub-array level main lobe anti-jamming methods: BMP,EMP and EP-CMR.Because BMP algorithm has the problem of peak shift of main lobe,while EMP algorithm and EP-CMR algorithm have large computational complexity in matrix eigendecomposition,and the three algorithms are poor in suppressing sidelobe interference when the main lobe interference is strong,an improved subarray interference suppression algorithm is introduced.In this paper,the Bayesian prediction density criterion is used to calculate the number of interference,and the spatial spectrum estimation method is used to calculate the angle of interference to distinguish the main lobe interference from the sidelobe interference.Then the blocking matrix based on Householder transform is used to eliminate the main lobe interference.Combined with the linear constraint to the sidelobe interference,a sub-array interference suppression algorithm suitable for real-time phased array radar is proposed.This method effectively solves the problem of main lobe offset,and reduces the complexity of the algorithm because there is no need to decompose the covariance matrix.Through the analysis of the simulation results,it can be seen that the method used in this paper can effectively suppress the main lobe interference and sidelobe interference under the strong main lobe interference,the shape preserving effect of the main lobe is good and the array response is stable.In the realization of the method,the phased array radar signal processing board is taken as the test platform.The paper first explains the design scheme of the system in terms of hardware platform and function design,and then discusses the implementation scheme of multi-core DSP from two aspects of algorithm module and interface module.Subsequently the system is further optimized on the basis of the improved algorithm proposed in this paper,and the processing performance of the system is improved by means of EDMA3 transmission and multi-core parallel processing.Finally,the feasibility of each function of the whole system is verified by the digital source signal,the processing results are analyzed,and the effect and advantage of the algorithm proposed in this paper in the engineering application of interference suppression are proved.