基于mTD-FrFT的VMFS-LFM信号参数估计方法

Parameters estimation methods of VMFS-LFM signals based on mTD-FrFT

针对甚小频偏线性调频(very minimum frequency shift-linear frequency modulation,VMFS-LFM)信号对应的分数阶傅里叶(fractional fourier transform,FrFT)域估计参数的绝对值接近1而导致估计性能降低的问题,在借鉴基于FrFT的LFM信号参数估计方法的基础上,采用m倍抽取(m time decimation,mTD)作为预处理方法,提出基于mTD-FrFT的VMFS-LFM信号参数估计方法.理论分析和实验结果表明:mTD预处理过程可增大VMFS-LFM信号和近参数多分量LFM信号的调频斜率在FrFT域的分辨率,使基于mTD-FrFT的参数估计方法可对VMFS-LFM信号和相近参数多分量LFM信号进行有效参数估计.

The parameters estimation performance of very minimum frequency shift linear frequency modulation （VMFS-LFM）signal based on fractional fourier transform（FrFT） is low due to the absolute value of VMFS-LFM＇s parameters in FrFT domain are be close to 1. To solve this question, two parameters estimation methods of VMFS- LFM signal based on m time decimation-FrFT （mTD-FrFY）were proposed, which m-time decimation was used as preprocessing methods. Theoretical analysis and simulation results showed that preprocessing of m-time decimation increased resolution ratio of frequency modulation slope of VMFS-LFM signal and muhi-component LFM signals with similar parameters in FrFT domain, and the accuracy of parameters estimation methods were increased.