Research And Implementation Of Subarray Adaptive Beamforming Technology

In order to obtain higher range resolution and angular resolution,large array radar systems tend to increase the antenna aperture.Hundreds or thousands of array units are used to form the antenna array.If each array unit has its own processing channel,full adaptive beamforming not only consumes many hardware costs,but also greatly increases the system calculation volume,which is difficult to design and implement in actual engineering.In order to overcome these difficulties,adaptive beamforming can be achieved at the subarray level,and all array units are divided into several subarrays.The array units in a subarray share the same processing channel.In this way,the system hardware cost and calculation volume will be greatly reduced,thus making engineering applications a reality.The main work completed in this article is as follows:The basic theory of adaptive beamforming is introduced firstly.For narrowband signal model related to engineering projects,the calculation method of array pattern is introduced,and then the differences between adaptive beamforming and conventional beamforming are compared.The detailed analysis and comparison of several optimal weight vector calculation criteria and classic adaptive algorithms are carried out through simulation.The related theory of adaptive beamforming at the subarray level is studied then.Based on the performance analysis of several subarray partition methods,a special-shaped subarray structure is proposed according to the performance requirements of the array signal processing system.The adaptive beamforming performance of the special-shaped subarray structure is indeed better than the common uniformly divided subarray structure according to the detailed comparison and analysis of the full arrays,uniformly divided subarrays,and special-shaped subarrays,which can be used in the array signal processing system.Aiming at the non-uniformly divided subarray structure,the noise power is normalized using the equal noise power method,and simulations verify that the method can indeed improve the performance of adaptive beamforming under this structure.Based on the hardware platform in the array signal processing system,this paper describes a design of beamformer under the DSP + FPGA architecture.Firstly,the adaptive weights are calculated by C programming language and DSP library functions in DSP,including the calculation of covariance matrix,matrix inversion and weight coefficients.Then the process of sending weight coefficients to the FPGA through the serial Rapid IO high-speed interface is implemented based on the high-speed transceiver structure,and the design methods on the DSP and FPGA sides are introduced in detail.Digital beamforming is realized through Verilog hardware description language and the cascade structure of multiply accumulator in FPGA,and the consumption of main resources is introduced.Finally,the feasibility of the above-mentioned design process was verified by system test,which illustrates that the design has practical engineering application value.