基于分数阶傅里叶变换的线性调频引信定距方法

针对调频（FM）引信，为了在较小的调制频偏内获得较高定距精度，提出了基于分数阶域瞬时初始频率估计和基于分数阶相关的两种定距方法。论述了两种方法的定距原理，分析了其距离分辨力与抗噪声性能，并进行了仿真验证。结果表明：较FM谐波定距方法，两种方法具有较高的距离分辨力，且受FM带宽影响较小；同时定距方法通过FM发射、接收信号与单载波混频方法，在分数阶域避免了FM率估计，降低了算法复杂度，具有工程可实现性；较初始频率估计方法，基于分数阶相关的FM定距方法抗噪声性能更好，适合于低信噪比环境下信号检测。

Research on Ranging Method for Linear Frequency Modulation Radio Fuze Based on Fractional Fourier Transform

To improve the ranging accuracy of the frequency modulation（FM）radio fuze under the limit of the little frequency deviation, two ranging methods, i.e. instantaneous initial frequency estimation method and fractional correlation method, for linear FM radio fuze based on fractional Fourier transform (FRFT) are proposed. The ranging principles of the two methods are described, their range resolutions and anti-noise performances are analyzed, and the simulations are carried out to validate these methods. The simulation results demonstrate that the ranging resolutions of the two methods which are affected by the modulation bandwidth rarely are much better than that of the ranging method based on the harmonic wave method. For the known frequency modulation rate, the complexity of the methods is reduced and acceptable for engineering realization. The fractional correlation method is better than the instantaneous initial frequency estimation method in anti-noise performance and can be used in the low signal-to-noise ratio circumstance.