基于FRFT的非线性调频信号双特征检测方法  

Double-characters detection of nonlinear frequency modulated signals based on FRFT

作　　者：许述文[1] 水鹏朗[1] 杨晓超[1] 

机构地区：[1]西安电子科技大学雷达信号处理国家重点实验室,西安710071

出　　处：《中国科学：信息科学》2011年第10期1200-1209,共10页Scientia Sinica(Informationis)

基　　金：国家自然科学基金(批准号:10990012)资助项目

摘　　要：强噪声中的未知非线性调频信号检测一直是实际检测领域中的一个难点问题.非线性调频信号的相位历史是关于时间的未知平滑函数,并且该函数不能或者很难用少量参数来建模.由于相位模型的缺失,我们提出一种基于接连分数阶Fourier变换和双特征检测的非参数化检测方法.检测方案包含3部分:首先,计算一个周期内接连角度的分数阶Fourier变换,将这些不同角度的变换结果构造成二维图像;然后,利用硬阈值处理获得二值图像,并利用多重中值滤波来去除该二值图像中的孤立噪声点,从而获得精炼的二值图像;最后,根据精炼图像提取2个互补的检测统计量,并通过双特征检测器判决目标是否存在.本文针对3类不同阶的多项式相位信号以及正弦相位信号的对比实验结果表明,提出的方法是有效且鲁棒的,并且获得了满意的检测性能.In many practical applications,signals to be detected are unknown nonlinear frequency modulated （FM） and are corrupted by strong noise.The phase histories of the nonlinear FM signals are assumed to be unknown smooth functions of time,which are usually poorly modeled or cannot be modeled at all by a small number of parameters.Because of the lack of phase model,a nonparametric detection method is proposed based on successive fractional Fourier transform and double-characters detection.The detection process goes in three steps.First,an image is constructed by the fractional Fourier transforms of successive angles in one period.Then,the threshold procedure is utilized to transform the image into a binary image.After the multiple median filtering,the binary image is refined where the isolated noise pixels are removed.Finally,two complementary features are extracted from the refined image,and a double-characters detector is proposed to decide whether the target is present or not.The simulation experiments to three polynomial phase signals with different orders and a sinusoidal phase signal show that the proposed detection method is effective and robust.

关 键 词：分数阶 FOURIER 变换 双特征检测 非参数化检测 多重中值滤波 

分 类 号：TN911.23[电子电信—通信与信息系统]