On Subarray Based Beamforming Techniques for Target Detection Using Underwater Sensor Arrays

The paper presents a comparison of two subarray based beamforming techniques namely the conventional frequency domain beamformer (CBF) and the split-beam cross-correlation (SBCC) beamformer, in terms of their ability to estimate the direction-of-arrival (DoA) of potential targets at sea. First the CBF technique is examined with three small sensor arrays called subarrays, separated by a fixed distance and placed in a line array configuration. Second is the SBCC technique that is widely used in array processing applications for DoA estimation of broadband signals using a linear array. In this paper, the SBCC technique is used to generate a fixed number of beams for each of the three subarrays, followed by cross-correlation of beams from first subarray with beams from second subarray or the cross-correlation of beams from third subarray with beams from second subarray. The second subarray in the middle is taken as a reference. Simulation results show that the SBCC technique using subarrays provides better DoA estimates for broadband signals radiated by targets at sea in comparison to the CBF technique. The results are presented in the form of bearing vs. amplitude and bearing vs. time plots for comparison.