Research on DOA Estimation of Nonstationary Signal Based on Fractional Fourier Transform

Abstract

In this paper, to estimate the DOA of nonstationary linear frequency modulation(LFM) signal in practical underwater environment, a method of DOA estimation based on fractional Fourier transform (FrFT) is investigated. Firstly, the transformation characteristics of FrFT on LFM signal are investigated. Secondly, the DOA estimation method based on FrFT is performed by following the thread of DOA estimation of narrowband signal, and the effect of focus performance of LFM signal in fractional Fourier (FrF) domain on DOA estimation is obtained through numerical simulations, which benefits the practical application of the method in underwater environment. Finally, an active detection experiment of DOA estimation by FrFT is conducted, which demonstrate that the method has a lower detection threshold and wider detection filed range compared with those in frequency domain.