DOA Estimation of Near-field Passive Sources with Acoustic Array Based on Fractional Fourier Transform

In this paper, we propose an efficient near-field source DOA estimation method based on the Fractional Fourier transform. In this method, the received data of the sensor array for the near-field source is modeled as a linear-frequency modulated (LFM) signal in spatial domain after the Fresnel approximation. Then the Fractional Fourier transform is employed to estimate the modulated frequency rate, which stands for the influence of quadratic phase of near-field source. After compensating this quadratic phase term, the received signal can subsequently be converted into a far-field expression. Finally, classical DOA estimation methods for far-field can be applied to find the direction of the source. In addition, for multiple sources, a CLEAN technique is proposed to extract the sources iteratively. Simulations are finally carried out to demonstrate its validity.