Insight Into Split Beam Cross-Correlator Detector With the Prewhitening Technique

The split-beam processing methods have been widely used for the bearing estimation of broadband signals with a line array. They can achieve high bearing resolution at a cost of the reduced processing gain. The split beam cross-correlator detector (SBCD), one of these methods, is to obtain a cross-correlation series from the redundant two-dimensional cross correlations between beam pairs of two sub-arrays. When SBCD is combined with prewhitening techniques in generalized cross correlation (GCC), it shows some unique output characteristics beneficial for both bearing estimation and detection, such as the low output background, the power-independent output, the capacity of accentuating weak targets, suppressing strong interferences, and the resistance to grating lobes aliasing in the spatial spectrum. This paper is to reveal these characteristics and underneath reasons through theories and simulations. Experiment results with an array of 268.75m in South China Sea validate the present theories, and manifest that SBCD with the prewhitening technique can achieve improved performances on both the direction-of-arrival (DOA) estimation and detection of weak broadband targets. In terms of efficiency and robustness for real time applications, it shows great potential in actual underwater environment.