A method to predict active sonar detection range in uncertain shallow water environments

Knowledge of maximum detection range is important for the appropriate operation of search sonar. For example, effective spacing of multistatic sonar sources and receivers will be influenced by good estimates of achievable detection range. But predicting detection range for low-frequency active sonar in shallow water can be problematic in the face of inadequate environmental characterization. Thus, incomplete knowledge of bottom sediment geoacoustics and bottom scattering strength, and absence of a good understanding of bottom reverberation mechanisms, will greatly hamper the accurate prediction of dependable detection ranges. Given a bistatic sonar configuration in shallow water, a method is proposed and described that exploits the observed transition time from reverberation to noise-limited conditions to simply and robustly predict maximum detection range for specified target strength. Modeling and analysis suggest that estimates of maximum detection range within 25% accuracy can be readily achieved.