Research On Anti-jamming Fast And Adaptive Beamforming Technology Of Plane Array In Airspace

Large antenna arrays are usually used in radar system to improve antenna gain and angel resolution.For large digital antenna arrays,the traditional adaptive digital beamforming algorithm can not meet the real-time requirements of radar system because of high computation complexity.Aiming at meeting the requirement of large digital antenna arrays,the fast adaptive beamforming algorithm and its implementation are studied from two aspects,which are reducing the number of snapshots required by the algorithm and reducing the computational dimension.The main contributions are illustrated as follows:1.Firstly,the uniform linear array signal model and the plane array signal model are both introduced.After that,the basic theoretical knowledge of beamforming and optimal criteria are introduced.At the same time,the simulation of optimal criteria are conducted.2.A two-dimensional blocking matrix of planar array is proposed then,which is suitable for orthogonal projection(OP)adaptive digital beamforming algorithm.The algorithm applys to uniform planar array of arbitrary structure.Simulation results show that the new algorithm provides good anti-interference performance and angle measuring performance.Besides,the adaptive weights can be calculated quickly with a few snapshots,which meets the real-time requirement of radar system.The new algorithm is advantageous to the project realization.3.Joint iterative optimal rank-reduction algorithms are studied then.A joint iterative optimization(JIO)algorithm based on recursive least square(RLS)and a JIO algorithm based on LCMV are derived one after another,the taylor weights are also added to the initial rank-reduction matrix to control the sidelobe level.The simulation results show that both two algorithms have good main lobe shape and anti-jamming performance.JIO-LCMV algorithm has less computation than JIO-RLS algorithm.It is a fast beamforming algorithm suitable for large antenna arrays.4.For the implementation of JIO-LCMV algorithm,a high-speed implementation scheme based on FPGA and DSP cascaded hardware platform is proposed.In each iteration process,the rank-reduction matrix is firstly updated in FPGA.Then,FPGA requests to communicate with DSP.The data are transmitted to DSP through the network port.After receiving the data,DSP updates the weights and judges whether the algorithm converges.If it does not converge,the updated data will be transmitted to the FPGA to start next iteration.The test results show that the algorithm has good main lobe and anti-jamming performance under different expected signal directions and different signal-to-noise ratios.In addition,thealgorithm calculate the final weights within 4.5 ms,which meets the real-time requirement of radar system.