CIRCUITS SYSTEMS SIGNALPROCESS VOL 2, NO. 4, I983 SOURCE-ORIENTED ADAPTIVE BEAMFORMING* 1 Salvatore D. Morgera 2 and Andrew C. Callahan 3 Abstract. A system concept expected to improve sonar multiple target detection and classification performance in severe directional interference environments is presented. Adaptive nulling of undesired strong interference sources and detection of desired weak sources are achieved by utilizing constrained adaptive processing techniques together with conventional processing techniques. The adaptive processing functions are incorpo:rated in the overall system architecture in a manner which maintains the computational complexity and storage requirements linearly proportional to the prod- uct of the number of interference sources and the number of adaptive weights per interference source. In addition, a detailed discussion is provided concerning the im- portance of certain a priori assumptions on constrained adaptive algorithm performance. 1. Introduction Directional[ acoustic sources of interest are attributed to commercial shipping, convoy ships, and legitimate targets. As the target detection sensitivity of modern sonar systems increases, so does the nontarget detection sensitivity. In order to exploit the increased target detection sensitivity, the modern sonar system must include effective means for performing target/nontarget discrimination. The system concept described here offers considerable prom- ise in this regard by utilizing adaptive processing techniques in a new man- ner. The techniques discussed also apply to the improvement of radar system detection and classification performance and satellite and terrestrial link com- munications performance in hostile environments. The overall system architecture presented here is influenced primarily by * Received March 21, 1982; revised May 18, 1983. This research was supported by NSERC Grant A0912 and Raytheon Company Indepen- dent Research and Development Programs. 2 Presently with Concordia University, Department of Electrical Engineering, 1455 de Maison- neuve Blvd. W., Montreal H3G 1M8, Quebec, Canada. 3 Presently with Raytheon Company, Advanced Technology Section, Submarine Signal Divi- sion, Portsmouth, Rhode Island 02871, USA.