天波雷达电离层污染校正与海杂波抑制

在天波超视距雷达（OTHR）中，舰船目标的多普勒频率与海杂波谱接近，电离层污染会导致海杂波频谱展宽，从而淹没邻近的舰船目标信号。考虑到电离层污染会导致OTHR回波信号的相位缓慢变化，提出了采用相位梯度法对回波信号进行电离层污染校正；利用污染校正后的海杂波可以近似为两个单频信号之和这一特点，提出了应用奇异值分解来实现对海杂波的抑制。仿真结果表明，文中算法可以有效地校正电离层污染，抑制海杂波，显著提高信杂比，从而有效解决强海杂波对舰船目标的遮蔽问题。与现有的HRR—SVD算法相比，文中算法可以适用于相干积累时间较长和电离层污染较大的情况，防止残留的海杂波形成虚警，提高了OTHR对海杂波附近舰船目标的检测能力。

A Cascaded Method for Ionospheric Decontamination and Sea Clutter Suppression in OTH Radar

In the over-the-horizon radar, the Doppler frequency of ship targets is close to the sea clutter spectrum, the ionospheric contamination will lead to the sea clutter broadening in Doppler domain, which will smear the neighboring ship target signals. Considering the ionospheric contamination led to the slow phase changes of the OTHR signal, the phase gradient based method to correct the ionospheric contamination is proposed. Take the feature that the sea clutter can be approximated to be two single-frequency signals after the ionospheric contamination correction, a singular values decomposition based ocean clutter suppression al- gorithm is used. The simulation results show that the proposed algorithm can effectively correct the iono- spheric contamination and suppress the sea clutter. The signal noise ratio is increased by more than 40 dB. The masking problem between the strong sea clutter and the ship target is solved. Compared with the HRR- SVD algorithm, the proposed algorithm can be applied in the condition of longer coherent integration time and larger ionosphere pollution. It can prevent the remains of sea clutter from forming a false alarm and improve the ship target detection performance of OTHR.