IMPLEMENTATION OF ADAPTIVE AND SYNTHETIC-APERTURE PROCESSING SCHEMES IN INTEGRATED ACTIVE-PASSIVE SONAR SYSTEMS

Progress in the implementation of state-of-the-art signal-processing s chemes in sonar systems is limited mainly by the moderate advancements made in sonar computing architectures and the lack of operational eva luation of the advanced processing schemes. Until recently, matrix-bas ed processing techniques, such as adaptive and synthetic-aperture proc essing, could not be efficiently implemented in the current type of so nar systems, even though it is widely believed that they have advantag es that can address the requirements associated with the difficult ope rational problems that next-generation sonars will have to solve. Inte restingly, adaptive and synthetic-aperture techniques may be viewed by other discipline as conventional schemes. For the sonar technology di scipline, however, they are considered as advanced schemes because of the very limited progress that has been made in their implementation i n sonar systems. This paper is intended to address issues implementati on, of advanced processing schemes in sonar systems and also to serve as a brief overview to the principles and applications of advanced son ar signal processing. The main development reported in this paper deal s with the definition of a generic beam-forming structure that allows the implementation of nonconventional signal-processing techniques in integrated active-passive sonar systems. These schemes are adaptive an d synthetic-aperture beam formers that have been shown experimentally to provide improvements in array gain for signal embedded in partially correlated noise fields. Using target tracking and localization resul ts as performance criteria, the impact and merits of these techniques are contrasted with those obtained rising the conventional beam former .