Abstract:
This paper details the implementation of adaptive processing schemes with near-instantaneous convergence in integrated active--passive sonar applications. The adaptive schemes of this investigation include a generalized sidelobe canceller (GSC), a coherent broadband adaptive algorithm based on a multiple steered covariance matrix and the MVDR method. The effort is part of a major study that includes the design of a generic signal-processing structure which allows the implementation of adaptive and synthetic aperture signal-processing schemes in real-time sonar systems. Application results from synthetic and real experimental datasets show that the adaptive processing schemes of this study provide continuous beam time series at the input of a matched filter and a spectrum analyzer for active and passive sonar applications, respectively. The same set of results demonstrates that the implementation scheme of this study eliminates undesirable adaptive performance degradation effects such as signal cancellation. In addition, the adaptive beam time series have temporal coherence properties equivalent to those of the conventional beam time series. Moreover, their amplitude of correlation with the reference FM signal of active sonars is the same with that of the conventional ``main stream`` schemes, which indicates that the adaptive algorithms have achieved near-instantaneous convergence.