全设计频段束宽恒定的低旁瓣时域波束形成

为了在空域无失真地接收宽带信号和有效地抑制环境干扰,提出了全设计频段束宽恒定的低旁瓣时域波束形成方法。首先,把宽带信号分为几个子带,应用半定规划的优化方法设计这些子带中心频率上的加权,使所形成的波束主瓣与设计带宽中最低频率上的波束相同,同时约束其具有低旁瓣特征。然后,设计FIR滤波器拟合这些离散频率点上恒定束宽加权所表示的幅相加权。显然,设计得到的FIR滤波器的幅相响应给出了全设计频段上的幅相加权。最后应用该方法,针对阵元具有方向性的12元均匀离散圆弧阵,设计覆盖一个倍频程的低旁瓣时域恒定束宽波束形成器,并使用线性调频信号作为测试信号,验证了所提方法的有效性。

Time domain low-sidelobe beamforming with constant beamwidth within the entire required frequency band

In modern sonar systems,wideband signals carrying more target information are often processed.Distortion of wideband signals caused by processing with traditional beamformer designed for narrow band signals is avoided by wideband constant beamwidth beamforming techniques.In this paper,time domain beamforming with constant beamwidth within the entire required frequency band is presented.First,the whole frequency band is decomposed into several subbands.Complex weights for center frequencies of these subbands are figured out using the semidefinite prog-ramming.In this process,low-sidelobe is constrained.An FIR filter is then designed to fit the amplitude and phase response that the complex weights represent.Computer simulation for LFM signals demonstrates the effectiveness of the proposed method.