一种天波雷达多径扩展多普勒杂波抑制方法

A Multipath Spread Doppler Clutter Suppression Method for Skywave Over the Horizon Radar

该文分析了天波超视距雷达(Over The Horizon Radar,OTHR)多径扩展多普勒杂波(Spread Doppler Clutter,SDC)的产生机理。由于阵列存在幅相误差且期望信号的功率大于SDC功率,自适应数字波束形成(Adaptive Digital Beam Forming,ADBF)将降低SDC抑制能力,同时还会导致信号对消,严重降低信噪比。针对以上问题,该文提出一种自适应抑制SDC的方法。该方法首先采用改进噪声子空间拟合自校正法消除阵列幅相误差,得到期望信号和SDC准确的到达仰角,然后采用正交投影权矢量进行ADBF处理,避免了强期望信号条件下ADBF权矢量估计不准的问题。理论分析和仿真实验表明该方法能够较彻底地抑制多径SDC。

This paper analyzes the production mechanism of the multipath Spread Doppler Clutter （SDC） in skywave Over The Horizon Radar （OTHR）. Because the amplitude and phase errors always exist in the array and the power of desired signal （sea clutter） is greater than the power of SDC, the SDC suppression ability declines through conventional Adaptive Digital Beam Forming （ADBF） process, at the same time, the desired signal is weakened and Signal-to-Noise Ratio （SNR） is seriously decreased. To resolve the above problems, an adaptive SDC suppression method is proposed. In this method, an improved Noise Subspace Fitting （NSF） method is utilized to eliminate amplitude and phase errors of OTHR array, and the direction of arrival angle of desired signal and SDC can be accurately obtained. Then, orthogonal projection weight vector is used in ADBF to solve the problem that conventional ADBF weight vector can not be accurately estimated because of the strong desired signal. Theoretical analysis and simulation results show that the scheme can completely suppress multipath SDC.