Direction of arrival estimation using virtual array search

This study explores the application of the advanced array interpolation technique for direction of arrival estimation. It uses an array of Global Positioning System (GPS) sonobuoys, as a method for enhancing the bearing estimation accuracy, improving target tracking capabilities. Currently, the bearing estimation of underwater targets using sonobuoys is based on fusion of bearings, obtained through individual element processing. This preserves the advantage of having a widely spread field of sonobuoys to detect underwater targets. However, the low levels of signal-to-noise ratio (SNR) jeopardise the bearing estimation accuracy. This can be improved using array processing of a directional frequency analysis and recording (DIFAR) sonobuoy field. The environmental conditions and deployment strategies impose limitations on the array processing of a DIFAR sonobuoy field. These factors mainly cause the array of sonobuoys to be a non-uniform sparse array. Advanced array interpolation is proposed to mitigate the current processing limitations degrading the system performance. This method is tested using acoustic level simulation. Simulation results show that the proposed method improves the processing of non-uniform sparse arrays based on the SNR and the inter-element distances of the array.