DOA estimation of coherent wideband LFM signals based on fractional fourier transform and virtual array

A method for the direction of arrival (DOA) estimation of coherent wideband linear frequency modulated (LFM) signals is researched based on fractional Fourier transform (FRFT) and virtual array transform. In this algorithm, the observed signals are first transformed to fractional Fourier domain, and then construct correlation signals matrix of the fractional Fourier domain, and the decorrelation ability is obtained by virtual array transform, which can settle the problem of not finding coherent signals in routine MUSIC and ESPRIT algorithm. Compare to the spatial smoothing algorithm, this approach can make the estimation accurate and does not decrease effective array aperture under a lower SNR and a smaller sampling number. Simulation results verify the correctness and efficiency of the new algorithm.