基于延时相关和FRFT的编队目标架次分辨方法

为较好满足窄带雷达的防空作战需求,提出了一种基于延时相关和分数阶傅里叶变换(FRFT)的空中编队目标架次分辨方法.该方法首先利用延时相关法粗略估计出回波信号的多普勒调频斜率,依据调频斜率和FRFT阶次的对应关系,获得最优变换阶次的粗略值;然后以FRFT后信号的熵值为最小化目标函数,提出一种精确搜索最优变换阶次算法,并以此最优变换阶次对回波信号进行FRFT,从而实现在分数阶多普勒域的目标架次分辨.仿真结果表明,本文所提方法具有较好的多普勒分辨性能,编队目标架次识别准确率较传统的短时傅里叶变换(STFT)、维格纳分布(WVD)分析方法有显著提高.

A sorties identification method of formation aircraft based on time delay correlation and FRFT

In order to better meet the requirements of narrowband radar air defense operations,this paper proposes a method of sorties identification of formation aircraft based on delay correlation and fractional Fourier transform(FRFT).Firstly,the delay correlation method is used to roughly estimate the Doppler frequency modulation slope of the echo signal.According to the correspondence between the frequency modulation slope and the order of FRFT,the rough value of the optimal transform order is obtained.Then,with the entropy value of the signal after the fractional Fourier transform taken as the minimization objective function,an optimal transform order algorithm for precise searching is presented,and the FRFT of the echo signal is carried out according to the optimal transform order,thus realizing the target sorties identification in the fractional Doppler domain.Simulation results show that the proposed method has better Doppler resolution performance,and the accuracy of formation target sorties identification is significantly improved compared with the traditional STFT and WVD analysis methods.