Beamforming Theory And Algorithm Based On Variable Fractional Delay Filtering

In recent years,with the development of electronic technology,array signal processing has become a popular issue in the current information processing field.Array signal processing mainly studies the theory,technology and application of spatially distributed sensor array signals' information processing.Adaptive beamforming technology is the basis of array signals and is widely applied in communication radar,image processing,power,mechanical vibration,biomedicine,etc.field.The signal decomposition and signal reconstruction problems of array signal processing correspond to spatial spectrum estimation and beamforming,respectively.However,with the development of information technology,it is inevitable to encounter the bottleneck problem that the coupling effect between the array elements is intensified and the performance and hardware and software costs are increased.We launched studies to solve the above two problems in beamforming problem,it is worth noting that this paper provides a new idea of beamforming: bypassing the calculation of the sample covariance matrix in the traditional technique,the delay of each array element signal is directly compensated accurately by filters,that is,the beamforming based on the fractional delay filtering.Firstly,in order to design variable fractional delay filters with low complexity and high accuracy,an efficient design method with controllable cut-off frequency is proposed,which integrates the analytic all-phase filter design,the cubic spline interpolation and Taylor series expansion.In the proposed design,not only the time delay of the filter can be precisely adjusted by setting the delay parameter,but also the tap coefficients of each subfilter in the Farrow structure can be rapidly configured via setting the cut-off frequency parameter thus the cut-off frequency of the filter can be adjusted flexibly.Secondly,in order to facilitate beamforming of sparse arrays,a DOA estimation method based on difference set traversal search is proposed,which can realize the conversion between physical sparse arrays and virtual Nyquist arrays,thereby effectively estimating the angle of arrival.Thirdly,an adaptive beamforming algorithm based on variable fractional delay filtering is proposed.The spatial freedom problem is transformed into the time sample tolerance problem in spectrum analysis,and the precise delay compensation is performed on the array element observation signal.The proposed algorithm has low complexity,high efficiency and high robustness to noise compared with other algorithms.Therefore,it has a broad application prospect in the field of array signal processing.