基于LVD与Zoom-FRFT的多分量LFM信号参数估计

Parameter estimation of multicomponent LFM signal based on LVD and Zoom-FRFT

针对基于分数阶傅里叶变换(FRFT)的多分量线性调频信号(MLFM)参数估计方法中计算量大、估算精度低等问题,本文提出了一种基于吕分布(LVD)与高分辨分数阶傅里叶变换(Zoom-FRFT)的参数估计方法。首先,对MLFM信号进行LVD,检测存在的分量个数,对各分量参数粗略估计,利用粗略调频斜率代入FRFT的参数估计公式,反向计算出FRFT的粗略变换阶次。然后,以粗略变换阶次为中心限定范围,设置精度,连续进行FRFT,从而提取峰值的坐标即精确变换阶次与粗略FRFT域坐标。最后,在精确变换阶次下,以粗略FRFT域坐标为中心限定区间,进行Zoom-FRFT,从而提取精确FRFT域坐标,对分量的参数进行精估计。仿真结果表明,该方法可以有效地对MLFM信号进行参数估计,并可以根据实际需要选择变换阶次的搜索范围与精度、FRFT域的细化倍数;与传统方法相比,本方法同时提高了参数估计精度与计算效率。

In order to solve the problems of heavy calculation burden and low estimation precision in multi-component linear frequency modulation(MLFM)parameter estimation method based on the fractional Fourier transform(FRFT),a method for parameter estimation based on Lv’s distribution(LVD)and Zoom-fractional Fourier transform(Zoom-FRFT)is proposed.Firstly,detecting the number of components and estimating parameters coarsely by LVD,using the coarse frequency modulation slope to calculate the coarse order by FRFT parameter estimation formula.Then,taking the coarse order as the center of limited interval,setting the precision,and continuously conducting FRFT,so as to extract the peak’s coordinates corresponding to the accurate order and coarse FRFT domain position.Finally,under the accurate order,taking the coarse FRFT domain positon as the center of limited interval to carry out Zoom-FRFT,so as to extract the accurate FRFT domain positon and accurately estimate parameters.The simulation result shows that the method can effectively estimate the parameters of MLFM signal,and select the search interval and precision of the order and the refinement multiple of the FRFT domain according to the requirement.Compared with the traditional method,it also improves the precision and computation efficiency of parameter estimation.