由于多径效应,米波雷达低仰角测高一般通过空间平滑去相干,或者由反射模型建立合成导向矢量,进而采用多信号分类、最大似然等仰角匹配算法来实现。但固定系数反射模型通常只能适用于平坦地形,在起伏地形条件下建立准确的变系数反射模型极困难。文中分析了目标位置变化过程中地面反射系数的变化情况,提出了一种通过检飞数据直接估算合成导向矢量的方法,以提高起伏地形条件下米波雷达低仰角测高算法的稳健性和精度。实验结果表明了所提方法的有效性,特别在目标距离较远时,使用所提方法得到的仰角精度明显优于传统方法。

Due to multipath effect, height-finding methods of VHF radar aiming at low-altitude targets are generally constructed by coherence-reducing space-smoothing techniques or synthetic steer vector techniques, both via reflection models, followed by elevation matching algorithms such as MUSIC or maximum-likelihood. However, traditional reflection models usually can only be applicable for flat reflecting surfaces. It is extremely difficult to build variant-coefficient reflection models for fluctuant terrains. In this paper, the varieties of reflecting-coefficient during target movements are analyzed, and an approach is proposed using flight test data to directly estimate the synthetic steer vectors, in order to guarantee the robustness and precision of low-altitude height-finding algorithms confronting the fluctuant terrains. The experimental results validate the proposed method, showing that the precision gained by the proposed method can be much better than traditional algorithms when the target is very far and signal-noise ratio is quite low.

TN953