分数阶Fourier域中多分量chirp信号的遮蔽分析

Analysis of the Shading Between Multicomponent Chirp Signals in the Fractional Fourier Domain

本文从分数阶Fourier变换与时频分布的关系入手,在离散分数阶Fourier变换算法基础上导出了单分量chirp信号分数阶Fourier谱强度的近似表达,并依据分数阶Fourier变换的线性性质,得到了调频率不同的两分量chirp信号间分数阶Fourier谱相互遮蔽的量化结果,给出了图例分析,并进行了仿真验证.通过本文的分析可以知道分数阶Fourier域中调频率不同的多分量chirp信号间的相互遮蔽主要取决于各自的幅度、调频率和采样时间.当多分量chirp信号幅度、调频率确定后,可以通过延长采样时间来降低各分量间的相互遮蔽.

Starting with the relationship between the fractional Fourier transform and the time-frequency distribution, we derives the approximate expression of the fractional Fourier spectrum intensity of a single chirp based on the digital computation of the fractional Fourier transform. The shading between the fractional Fourier spectra of two chirps with different chirp rates is analyzed, and a formula is obtained,which is illuminated by some figures and verified by a simulation.We find that the amplitude,chirp-rate and sampling interval determine the shading between the fractional Fourier spectra of multicomponent chirp signals. Prolonging the sampling interval can reduce the shading when amplitude and chirp-rate of multicomportent chirp signals are determined.