快速校正天波雷达电离层相位污染的改进方法

An Improved Method for Fast Correcting Ionospheric Phase Contamination in Over- The- Horizon Radars

时变的电离层会对天波超视距雷达(OTHR)回波信号相位进行调制,产生相位污染,导致回波谱展宽。最大似然估计(MLE)法具有比相位梯度法更佳的污染校正效果,但计算量非常大。通过引入投影近似子空间跟踪法,提出了一种改进的MLE方法。改进方法采用递归手段估计最大特征值对应的特征向量,避免了特征值分解过程,能够显著降低计算量,污染校正效果与MLE法相当。理论分析与仿真对比表明改进方法普适性强,计算量只有MLE法的万分之一,更适合工程实现。

The phase perturbation occurs when phase of over-the-horizon radar（OTHR） echo signal is modulated by the time-varying ionosphere and the echo spectrum is widened. The maximum likelihood estimation（ MLE） method has better estimation performance of phase error than phase gradient autofocus （PGA） method. However,this method has a large amount of computation which limits the real-time application. In this paper, an improved MLE method is proposed based on the projection approximation sub-space tracking approach. The improved method uses recursion algorithm to estimate the eigenvector of the maximum eigenvalue and avoids the eigenvalue decomposition process. The improved method has a comparable perturbation correcting performance to the MLE method and can significantly reduce computation. Theoretical analysis and simulation results show that the improved method has good universality for various forms of phase perturbation,the computation is only 1/10000 of MLE method,thus more available for engineering implementation.