Research On Beamforming Algorithms For Wideband Signals

As an important branch of array signal processing techniques,adaptive beamforming technology has been widely used in radar,sonar,communications and other fields.Wideband beamforming has been gradually become a hot issue in the field of array signal processing because of its advantages on carrying large amount of information and weak correlation of reverberation.Based on the discussion of classic narrowband beamforming,this paper deeply inverstigated the algorithms of wideband beamforming: time-domain wideband beamforming and frequency domain wideband beamforming.It focused on the constant beamwidth,null broaden and worst case performance optimization which relates to the robustness of the algorithms.The main work in this paper can be summarized as follows.1.Classical narrowband beamforming algorithms and theories are studied,such as LCMV,SMI,LSMI,ESB and so on.Both the advantages and disadvantages of the time domain and frequency domain wideband beamforming algorithms are analysed.Focused on the problem of wideband constant beamwidth beamforming,this paper combine with focusing transform algorithm and Bessel kernel function decomposition algorithm to present the constant beamwidth.2.On the basic of SDL array structure,SRV constraint is used to achieve the same response in beam main lobe for each subband.Then,based on the constant beamwidth,a new algorithm which realized the null broaden in all of the band with the use of SRV is proposed.3.Considering the existence of DOA estimation error,the problem of the desired signal's receiving without distortion is turned into a convex optimization problem by introducing the ellipsoid indefinite set.The simulation results show that the proposed method is robust to the dismatch of DOA estimation.