宽带波束域相干信号子空间高分辨方位估计

Broadband high-resolution direction-of-arrival estimation using beamspace coherent signal subspace approach

提出了宽带波束域相干信号子空间目标高分辨方位估计的频域处理与时域处理方法。分别设计出一组覆盖观察扇面的频域和时域低旁瓣恒定主瓣响应宽带波束形成器,然后对频域或时域波束形成器输出数据运用MUSIC方法估计目标方位。时域处理方法不需要进行频带分解,相对于频域处理需要较少的缓存和运算量。所提出的方法还可以在保证波束主瓣响应恒定的同时,通过在旁瓣区域形成期望宽度和深度的凹槽,用于抑制观察扇面外强干扰源。计算机仿真结果表明,本文的时域处理方法能够获得与本文频域处理方法相近的方位分辨与估计性能,它们都能够分辨相干信号源,且方位分辨与估计性能都高于已有方法。通过在干扰方位设计凹槽,较好地抑制了观察扇面外强干扰源,改善了对相干的弱信号源的方位分辨与估计性能。

Frequency-domain and time-domain beamspace preprocessing approaches to direction-of-arrival （DOA） estimation for multiple broadband farfield signals are proposed. A set of beamformers with constant main beam response is designed to cover the angular sector of interest. And the array snapshots are passed through the beamforming preprocessors prior to application of MUSIC. The time-domain processing is computationally less expensive since it eliminates the need for frequency decomposition. For the scenario of strong out-of-band interfering sources, our approach can form nulls or notches in the direction of them and guarantee that the main beam response of the beamformers are constant over the design band. Numerical results show that the proposed time-domain processing has comparable performance with the frequency-domain processing method, and both of them are able to resolve correlated source signals and provide lower resolution threshold and lower Root-Mean-Square Error （RMSE） of estimate compared with the existing methods. Our beamspace DOA estimator maintains good DOA estimation and spatial resolution capability in the scenario of strong out-of-band interfering sources.