改进型SVD-FRFT海杂波抑制方法

Improved SVD-FRFT sea clutter suppression method

海杂波回波能量较高且频谱较宽,常常会淹没慢速小目标的回波信号。为此,提出了一种新的基于时频信息的奇异值分解分数阶傅里叶变换海杂波抑制方法,所提方法采用分块处理、整体判决的思路。首先对较长的回波序列划分子脉冲块,分别提取每个子脉冲块的前Q阶信号分量并进行块间信号关联,实现目标信号与杂波的初步分离;接着进行自适应分段奇异值分解分数阶傅里叶变换处理,实现各阶信号分量的进一步提纯;最后采用归一化时频脊二次拟合误差对各阶分量进行判决,保留目标信号,滤除杂波信号。在仿真和实测数据上验证了所提方法的有效性及可靠性,相比于现有海杂波抑制方法,所提方法能够适应脉冲回波序列信杂比的变化,并且在信杂比较低及多目标环境中,仍能有效抑制海杂波,提取目标信号。

The returns of slow and dim targets,which have high energy and a wide frequency spectrum,are often submerged in the sea clutter.This paper proposes a new SVD-FRFT-based sea clutter suppression method using time-frequency information.The proposed method adopts the strategy of block processing and overall judgment.First,the long echo sequence is divided into sub-pulse blocks,with the first Q-order signal components of each sub-pulse block being respectively extracted and inter-block signal correlation performed to realize the preliminary separation of the target and clutter.Then an adaptive segmented SVD-FRFT processing is used to achieve further purification of the signal components of each order.Finally,the normalized ime-frequency ridge quadratic fitting error is used to judge the components of each order.In this way,the target is retained while the sea clutter is suppressed.The effectiveness and robustness of this approach is verified by the real sea clutter data.Compared with the classical sea clutter suppression methods,the proposed method can effectively suppress the sea clutter and extract target signals regardless of signal-to-clutter ratio(SCR),especially for the multi-target.