Direction-of-arrival estimation by asymmetric amplitude interpolation

Abstract

Amplitude comparison is a traditional method to estimate Direction-of-arrival(DOA) based on beamforming. Due to its low computational complexity, the method has been widely used in many fields especially for radar and sonar systems. However, the original “amplitude comparison” method considers the spatial spectrum and beampattern to be axis-symmetric, and the DOA estimation error rises sharply when the true DOA deviates from 0°. Considering the beamwidth difference between the left and right halves, asymmetric method is presented in this paper. Linear, quadratic and Gaussian interpolation methods are revised to be asymmetric through theoretical derivation. Asymmetric interpolation functions are adjusted to the steering angle. Furthermore, the influence of signal-to-noise ratio(SNR) is analyzed, and an amendment is employed to improve the robustness of the method at low SNR. Compared with the symmetric methods, the asymmetric methods can reduce the DOA estimation error significantly. The effectiveness of the proposed methods are demonstrated by numerical simulation and processing of experimental data on the lake.